Materiały źródłowe

• #1 Patella Dislocation – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK538288/

  Acute patellar dislocations typically occur as a result of trauma, usually a non-contact twisting injury to the knee, or from a direct blow to the medial aspect of the knee. A common mechanism is external tibial rotation with the foot fixed on the ground. […] Acute patellar dislocations typically occur as a result of trauma, usually a non-contact twisting injury to the knee, or from a direct blow to the medial aspect of the knee. A common mechanism is external tibial rotation with the foot fixed on the ground. Patellar dislocations can also occur in patients with generalized ligamentous laxity. However, those patients mostly tend to have recurrent subluxations of their patella as opposed to a frank dislocation. […] Patellar dislocations tend to occur in a lateral direction, partly because the direction of pull of the quadriceps muscle is slightly lateral to the mechanical axis of the limb. Medial instability is rare and more likely to result from congenital conditions, quadriceps atrophy, or iatrogenically. Intra-articular dislocation is also uncommon, but can occur following trauma where the patella is avulsed from the quadriceps tendon and is then rotated. Superior dislocations can occur in elderly patients where forced hyperextension causes the patella to lock on an anterior femoral osteophyte.

• #2 Patellar dislocation • LITFL • Trauma Library

  https://litfl.com/patellar-dislocation/

  The most common location of patella dislocations is lateral dislocation. […] Generally there is two types of mechanisms that result in patella dislocations. Type 1: results when there is a powerful contraction of the quadriceps in combination with sudden flexion and external rotation of the tibia on the femur. This is the most common reason for the patellar to dislocate. […] Type 2: results from direct trauma to the patella with the knee in flexion, can cause dislocation, however this is seen uncommonly.

• #3 Patellar dislocation • LITFL • Trauma Library

  https://litfl.com/patellar-dislocation/

  The most common location of patella dislocations is lateral dislocation. […] Generally there is two types of mechanisms that result in patella dislocations. Type 1: results when there is a powerful contraction of the quadriceps in combination with sudden flexion and external rotation of the tibia on the femur. This is the most common reason for the patellar to dislocate. […] Type 2: results from direct trauma to the patella with the knee in flexion, can cause dislocation, however this is seen uncommonly.

• #4 Patellar Dislocation (Acute) | Pediatric Orthopaedic Society of North America (POSNA)

  https://posna.org/physician-education/study-guide/patellar-dislocation-(acute)

  Acute patellar dislocations are common in adolescents and most occur secondary to noncontact mechanisms. […] Acute patellar dislocations can occur secondary to a traumatic event in patients without anatomic risk factors or secondary to indirect trauma in patients with anatomic factors predisposing them to patellar instability. […] Most acute dislocations are the result of noncontact mechanisms in which the knee is subject to a valgus force with internal rotation of the femur and a planted foot. […] This indirect mechanism of injury is responsible for 66-82% of acute patellar dislocations. […] A direct blow to the knee may also result in a traumatic patellar dislocation. […] Gallie first recognized a distinction between acute patellar dislocations in individuals with normal anatomy and those with predisposing anatomic risk factors for dislocation.

• #5 How To Identify and Treat Patellar Dislocation Versus Knee Dislocation – ACEP Now

  https://www.acepnow.com/article/how-to-identify-and-treat-patellar-dislocation-versus-knee-dislocation/

  Patellar dislocation occurs when there is disarticulation of the patella bone from the patellofemoral joint. It usually occurs from low-to-moderate trauma sustained during sports or other physical activity. Risk factors for patellar dislocation include structural variants of the patella or femoral trochlea, ligamentous laxity, trauma, and connective tissue disorders. Patellar dislocations represent 3 percent of knee injuries, with a high recurrence rate ranging from 15 to 44 percent for first-time dislocations and 50 percent with a previous history of two or more dislocations. […] The mechanism in the vast majority of patellar dislocations is noncontact involving knee flexion, a valgus force with external rotation. […] Knee dislocation is a dislocation of the tibia with respect to the femur and is seen in high-energy traumas including motor vehicle accidents, falls from heights, industrial injuries, and sports injuries, as well as spontaneously in the morbidly obese during ambulation.

• #6 Patella dislocation: an online systematic video analysis of the mechanism of injury | Knee Surgery & Related Research | Full Text

  https://kneesurgrelatres.biomedcentral.com/articles/10.1186/s43019-020-00031-w

  The mechanism of injury (MoI) for a patellar dislocation has not been fully established. The aim of this study was to use systematic video analysis to determine the MoI of a patella dislocation. […] The most common mechanism was an unbalanced individual with a flexed hip sustaining a valgus force to their flexed knee with the tibia externally rotated. […] This study provides some insight into the MoI for a patellar dislocation and the findings may assist in developing injury prevention programmes and rehabilitation protocols as well as guiding future research. […] We have found that the majority of patella dislocations occur in an unbalanced individual during a non-contact situation, where a valgus force is applied to a flexed knee. The quadriceps muscles are contracted at the time of injury, the tibia is externally rotated, and the hip is likely to be flexed. […] A patella dislocation is predominantly a non-contact injury. The most common mechanism of a patella dislocation in our series was that of an unbalanced individual with a flexed hip, sustaining a valgus force to their flexed knee with the tibia externally rotated.

• #7 Injury mechanism of patellar dislocation in professional athletes: a video analysis study | 2023, Volume 58, Issue 3 | Turkish Journal of Sports Medicine

  https://journalofsportsmedicine.org/full-text/706/eng

  Patellar dislocation (PD) is a devastating injury in professional athletes. An important aspect of injury prevention requires not only identifying the risk factors but also determining the responsible injury mechanism. The most important findings of this study were that patellar dislocation occurred when the trunk, hip, knee and ankle were slightly flexed. Dislocation occurred with the contraction of the quadriceps while the foot and tibia were performing external rotation. In professional athletes, PD most frequently occurs during a collision. The most common posture of the athlete who lost his balance is the trunk in flexion, knee and hip in flexion, ankle in plantar flexion. The mechanism of injury was analyzed in the following two categories: non-contact and contact injuries. In 72.2% of the athletes, the injury occurred via a contact mechanism. Of these, 61.5% were caused by direct contact with the knee. Patellofemoral dislocation is accompanied by hip flexion. Simultaneously, internal rotation of the femur is accepted as part of the mechanism by which a lateral patellar dislocation occurs. Patellar dislocation occurred with the contraction of the quadriceps, with the knee under load.

• #8 Patella Dislocation – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK538288/

  Individuals with an increased Q angle are predisposed to dislocation. The Q angle is measured by drawing a line from the anterior superior iliac spine (ASIS) through the center of the patella, and a second line from the center of the patella to the tibial tubercle. Normal Q angle measurement is typically higher in females than in males, 18 degrees compared to 14 degrees. Measurements that exceed those normals predispose the patient to patellar instability. […] There are several static and dynamic stabilizers of the patella. The medial patellofemoral ligament (MPFL) is the primary static restraint to lateral patellar instability during the first 20 degrees of knee flexion. This ligament is almost always torn with patellar dislocations. The bony structure of the patellofemoral joint is another static stabilizer, especially during deeper knee flexion angles. Anatomical factors that predispose to dislocation include patella alta (high riding patella), trochlear dysplasia or lateral femoral condyle hypoplasia, and excessive lateral patella tilt. Distortion of the normal patellorfemoral joint anatomy places the patella at higher risk for instability and dislocation. The main dynamic stabilizer of the patella is the vastus medialis obliquus (VMO) muscle. This is the most distal portion of the quadriceps muscle, and exerts a medially directed pull which helps maintain the patella well positioned. Weakness or dysplasia of this muscle increases the risk for dislocations.

• #9 Patella Dislocation – How Long is Recovery Time? | Jeremy Burnham, MD

  https://www.jeremyburnhammd.com/patella-dislocation-dislocated-kneecap/

  The patella, or kneecap, is a small bone that sits in front of the knee joint. […] However, sometimes the patella can become dislocated. This means that it slips out of place, usually to the outside of the knee. Patella dislocation occurs when the patella slides out of its normal position. This can happen if there is a sudden force applied to the knee, such as during a fall or car accident. […] There are many components that contribute to dislocation of the kneecap. There are bony stabilizers, such as the shape of the patella and the shape of the trochlea (the groove that the kneecap slides back and forth in). There are also soft tissue stabilizes, such as the medial patellofemoral ligament (MPFL). This ligament acts as a check rein to keep the patella from sliding too far to the outside of the knee.

• #10 Patellar Dislocation – SportsMD

  https://www.sportsmd.com/sports-injuries/knee-injuries/patellar-dislocation-instability/

  As the athlete suffers a patellar dislocation there may be other injuries that occur within the knee joint itself. […] Factors related to the knee include poor bony development of the trochlear groove at the end of the thigh bone (femur) in which the patella normally glides. This is termed trochlear dysplasia and when present provides less than normal bony resistance to the patella dislocating. […] If the attachment of the patellar tendon to the lower leg bone (tibial tubercle) is rotated too far to the outside, there is an inherent lateral (toward the outside of the knee) pull on the patella. […] If the MPFL is deficient it can be either repaired or reconstructed with a graft. […] If the tibial tubercle is rotated too much, then it can be cut (osteotomy) and reattached with screws at an improved location. […] In the rare case where the groove for the patella (trochlear groove) is too shallow, then this may have to be addressed with surgery to make the groove deeper.

• #11 Physiotherapy in Calgary for Hip – 1591

  https://www.northernhillsphysio.com/Injuries-Conditions/Hip/Research-Articles/Can-A-Normal-Patella-Dislocate/a~1591/article.html

  Can a healthy and normally aligned patella (kneecap) dislocate? Many experts have debated this question. […] Anatomic variations from the norm are linked with both acute (sudden) and chronic (repeated) dislocations. […] There is some evidence that no amount of force will pop the patella off the knee unless there is an underlying reason. […] A complete understanding of these features is essential in treating patellofemoral instability (dislocation) with any kind of success. […] Some people are born with a greater than normal angle where the femur and the tibia (shinbone) come together at the knee joint. This is called the Q-angle. […] When the quadriceps muscle contracts, the angle in the knee straightens, pushing the patella to the outside of the knee. […] In cases where this angle is increased, the patella tends to shift outward with greater pressure.

• #12 Physiotherapy in Calgary for Hip – 1591

  https://www.northernhillsphysio.com/Injuries-Conditions/Hip/Research-Articles/Can-A-Normal-Patella-Dislocate/a~1591/article.html

  Anatomic variations in the bones of the knee can occur such that one side of the femoral groove is smaller than normal. […] This creates a situation where the groove is too shallow, usually on the outside part of the knee. […] People who have a shallow groove sometimes have their patella slip sideways out of the groove, causing a patellar dislocation. […] If this occurs repeatedly, degeneration of the patellofemoral joint occurs fairly rapidly. […] People who have a high-riding patella are also at risk of having their patella dislocate. […] A strong contraction of the quadriceps muscle can easily pull the patella over the edge and out of the groove, leading to a patellar dislocation. […] Any of these changes in the normal anatomical structure, especially when combined with enough force can cause the patella to dislocate.

• #13 Patellar dislocation – Wikipedia

  https://en.wikipedia.org/wiki/Patellar_dislocation

  A predisposing factor is tightness in the tensor fasciae latae muscle and iliotibial tract in combination with a quadriceps imbalance between the vastus lateralis and vastus medialis muscles can play a large role, found, mainly, in women involved in sports. […] The pathophysiology of the kneecap is complex, and deals with the osseous soft tissue or abnormalities within the patellofemoral groove. The patellar symptoms cause knee extensor dysplasia, and sensitive small variations affect the muscular mechanism that controls the joint movements. […] When there is too much tension on the patella, the ligaments will be susceptible to tearing due to shear force or torsion force, which then displaces the patella from its groove. […] Patellar dislocation may also occur when the trochlear groove is shallow, a condition defined as trochlear dysplasia. […] Displacement of the patella laterally out of its groove strains the medial stabilizing connective tissues, particularly the medial patellofemoral ligament (supporting 5080% of the knee mechanisms in lateral patellar glide), which is torn usually at its femoral attachment.

• #14 Patella Dislocation – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK538288/

  Individuals with an increased Q angle are predisposed to dislocation. The Q angle is measured by drawing a line from the anterior superior iliac spine (ASIS) through the center of the patella, and a second line from the center of the patella to the tibial tubercle. Normal Q angle measurement is typically higher in females than in males, 18 degrees compared to 14 degrees. Measurements that exceed those normals predispose the patient to patellar instability. […] There are several static and dynamic stabilizers of the patella. The medial patellofemoral ligament (MPFL) is the primary static restraint to lateral patellar instability during the first 20 degrees of knee flexion. This ligament is almost always torn with patellar dislocations. The bony structure of the patellofemoral joint is another static stabilizer, especially during deeper knee flexion angles. Anatomical factors that predispose to dislocation include patella alta (high riding patella), trochlear dysplasia or lateral femoral condyle hypoplasia, and excessive lateral patella tilt. Distortion of the normal patellorfemoral joint anatomy places the patella at higher risk for instability and dislocation. The main dynamic stabilizer of the patella is the vastus medialis obliquus (VMO) muscle. This is the most distal portion of the quadriceps muscle, and exerts a medially directed pull which helps maintain the patella well positioned. Weakness or dysplasia of this muscle increases the risk for dislocations.

• #15 Patella Dislocation – knee Injury – Eddie O’Grady Physiotherapist

  https://www.physiotherapiststralee.ie/patella-dislocation/

  The vastus medialis obliqus muscle (VMO) is part of the quadriceps muscle group on the inside of the thigh, and is responsible for maintaining the stability of the patella towards the inside of the knee. If the VMO isnt strong enough, the patella is much more susceptible to dislocation. […] The Q-angle of the knee is the angle formed by lines representing the pull of the quadriceps muscle and the axis of the patellar tendon. People with an increased Q ankle are often termed knock kneed. This angle when too large increases the risk of patellar dislocation. […] The prevailing theory has been that lateral patellar tracking is associated with VMO weakness. However, research has been inconclusive for VMO weakness as a direct causative mechanism of lateral patellar tracking(patellar subluxation/dislocation). Recent findings have shown that general quadriceps strengthening has demonstrated reductions in lateral tracking irrespective of the mechanism.

• #16 Kneecap Dislocation | Knee Specialists

  http://www.kneespecialists.co.uk/conditions-procedures/knee-conditions/kneecap-dislocation/

  The stability of the kneecap is dependant upon the shape of the joint, the ligaments and the muscles with an overall general tendency for the kneecap to move outwards due to the alignment of the thigh bone on the shin bone. […] When the kneecap dislocates it moves off the front of the thigh bone to sit on its outside. […] The most common abnormality is a shallow or non-existent groove (trochlea) on the front of the thigh bone (called trochlea dysplasia), with less commonly a high kneecap (patella alta) or twisted thigh and shin bones (femoral and tibial torsion). […] The medial patellofemoral ligament is a fibrous structure that runs from the inner aspect of the kneecap to the inner aspect of the thigh bone. It is said to provide up to 60% of the stability to the kneecap in a normal shaped knee and has to rupture to allow the kneecap to dislocate. […] In people in whom the groove on the front of the thigh bone has failed to develop, a bump rather than groove will be present resulting in a high chance of recurrent dislocations of the kneecap off the outside of the bump.

• #17 Dislocated Kneecap (Patella Dislocation): Symptoms & Recovery

  https://my.clevelandclinic.org/health/diseases/21633-patellar-dislocations

  A dislocated kneecap (patella dislocation) occurs when your kneecap pops sideways out of its vertical groove at your knee joint. Its usually caused by force, from a collision, a fall or a bad step. A dislocated patella is painful and will prevent you from walking, but its easy to correct and sometimes corrects itself. […] A patella dislocation occurs when your kneecap (patella) slides out of the groove at your knee joint. […] When your patella dislocates, its forced outside of the trochlear groove and can no longer move up and down. This locks your knee and pulls the ligaments out of place, often tearing them. […] Most frequently, your kneecap pops out laterally (to the side of the groove). Like any dislocation, a dislocated kneecap is painful and debilitating until you correct it. But a dislocated patella will sometimes correct itself.

• #18 Patellar dislocation – Wikipedia

  https://en.wikipedia.org/wiki/Patellar_dislocation

  A predisposing factor is tightness in the tensor fasciae latae muscle and iliotibial tract in combination with a quadriceps imbalance between the vastus lateralis and vastus medialis muscles can play a large role, found, mainly, in women involved in sports. […] The pathophysiology of the kneecap is complex, and deals with the osseous soft tissue or abnormalities within the patellofemoral groove. The patellar symptoms cause knee extensor dysplasia, and sensitive small variations affect the muscular mechanism that controls the joint movements. […] When there is too much tension on the patella, the ligaments will be susceptible to tearing due to shear force or torsion force, which then displaces the patella from its groove. […] Patellar dislocation may also occur when the trochlear groove is shallow, a condition defined as trochlear dysplasia. […] Displacement of the patella laterally out of its groove strains the medial stabilizing connective tissues, particularly the medial patellofemoral ligament (supporting 5080% of the knee mechanisms in lateral patellar glide), which is torn usually at its femoral attachment.

• #19 How To Fix a Dislocated Knee | Symptoms & Treatment

  https://www.stoneclinic.com/patelladislocation

  Patellar dislocation is usually caused by either a direct trauma to the knee (e.g. a helmet hitting the knee) or from a sudden twist or pivoting of the leg (e.g. a ballet dancer landing poorly). A dislocation occurs when the patella shifts out of its normal position in the patellofemoral groove (trochlea), the V-shaped notch on the front of the femur. […] In cases of complete dislocation, the ligament holding the patella in place must tear or severely stretch. Unfortunately the articular cartilage bearing surface between the patella and the femur is impacted and can be also be damaged. […] For patellar dislocations resulting in a damaged ligament, we will most often reconstruct the damaged ligament (patellofemoral ligament) surgically using a donor tendon. If there is damage to the articular cartilage in the joint, we can treat it arthroscopically. Failure to address these issues may lead to a chronically unstable patella and potentially an arthritic knee.

• #20 Traumatic Patellar Dislocation – Hughston Clinic

  https://hughston.com/wellness/traumatic-patellar-dislocation/

  During a traumatic event, such as a fall, auto accident, or sports injury, the patella (kneecap) can completely or partially dislocate. A patellar dislocation occurs when the patella jumps out of the trochlear groove (a groove that holds the patella in line) and usually moves toward the outside of the knee. […] A MPFL tear allows the patella to move out of place; and then, when it returns to its normal position, the patella damages the trochlea, causing bone bruising or fractures. […] This injury can have long-term consequences, such as instability of the patella, pain, recurrent dislocation, and patellofemoral osteoarthritis. […] Surgery would include knee arthroscopy, to look at the inside of the knee for damage, and an open procedure to stabilize the patella. This can be done with a procedure called proximal extensor mechanism realignment. This procedure takes tissue available in the knee and tightens the stretched-out structures. It also loosens tighter structures to balance the forces of the patella, and the trochlea groove it slides in.

• #21 Dislocated Kneecap (Patella Dislocation): Symptoms & Recovery

  https://my.clevelandclinic.org/health/diseases/21633-patellar-dislocations

  A dislocated kneecap (patella dislocation) occurs when your kneecap pops sideways out of its vertical groove at your knee joint. Its usually caused by force, from a collision, a fall or a bad step. A dislocated patella is painful and will prevent you from walking, but its easy to correct and sometimes corrects itself. […] A patella dislocation occurs when your kneecap (patella) slides out of the groove at your knee joint. […] When your patella dislocates, its forced outside of the trochlear groove and can no longer move up and down. This locks your knee and pulls the ligaments out of place, often tearing them. […] Most frequently, your kneecap pops out laterally (to the side of the groove). Like any dislocation, a dislocated kneecap is painful and debilitating until you correct it. But a dislocated patella will sometimes correct itself.

• #22 Lateral patellar dislocation | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/lateral-patellar-dislocation?lang=us

  Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patella due to disruptive changes to the medial patellar retinaculum. […] Patellar dislocation most commonly results from a twisting motion, with the knee in flexion and the femur rotating internally on a fixed foot (valgus-flexion-external rotation). […] The presence of an abnormal medial patellar retinaculum should suggest the diagnosis of transient lateral patellar dislocation. […] The trochlear groove and patella may have abnormal morphology that predisposes to patellar dislocation.

• #23 Patellar Dislocation – Emergency Department

  https://www.rch.org.au/clinicalguide/guideline_index/fractures/Patellar_Dislocation_-_Emergency_Department/

  Dislocation of the patella is a relatively common injury in the active adolescent population and usually a traumatic event associated with either an awkward fall or direct trauma to the patella itself. […] When the patella dislocates it may damage the articular cartilage resulting in chondral scuffing or an osteochondral fracture from either the lateral femoral condyle or patella itself. […] Recurrent dislocation may be related to damage to the medial patellofemoral ligament, abnormal shape / site of the patella, shape of the trochlear groove or a combination of these. Hypermobility of the joint can also lead to recurrent dislocation. […] The presence of a significant chondral or osteochondral fragment on MRI requires operative treatment to remove, reattach or replace the fragment. Acute reconstruction of the torn soft tissue structures (most notably the medial patellofemoral ligament) is usually not required as this does not appear to influence the long term outcome of an acute dislocation. […] Acute patellar dislocation is a significant knee injury that in the otherwise normal knee results in recurrent instability in over a third of patients.

• #24 Patellar Dislocation | Orthopedics & Sports Medicine

  https://health.uconn.edu/orthopedics-sports-medicine/conditions-and-treatments/where-does-it-hurt/knee/patellar-dislocation/

  Patellar (kneecap) dislocations occur with significant regularity, especially in younger athletes, with most of the dislocations occurring laterally (outside). […] Following a patellar dislocation, the first step must be to relocate the kneecap into the trochlear groove. […] Associated problems normally occur with patellar dislocations, the most obvious of which is tearing of the ligaments that stabilize the kneecap itself. […] In the case of patellar dislocation, the ligaments on the inside of the knee are the most commonly injured as the kneecap slides laterally. […] Of much more concern are the small fragments of cartilage and bone that often are knocked off of the kneecap or the lateral femoral condyle during the relocation of the kneecap. […] Patellar dislocations can also cause significant quadriceps muscle injuries, which can be made worse due to the effusion within the knee or to early onset of exercises and premature return to play.

• #25 Patellar Dislocation (Acute) | Pediatric Orthopaedic Society of North America (POSNA)

  https://posna.org/physician-education/study-guide/patellar-dislocation-(acute)

  Osteochondral injury as a result of patellar dislocation ranges from 5% to 50%, although Seeley reported an incidence as high as 73%. […] In cases in which there is a large knee effusion, aspiration may be used to improve comfort and motion recovery. […] Acute surgical treatment is performed for loose body removal or for fixation of osteochondral fractures. […] Surgical treatment is indicated in the above setting and in cases of recurrent instability. […] A consequence of recurrent patellar instability may be patellofemoral osteoarthritis. […] Overall however, recurrent instability rates are similar for nonoperative and operative management in the case of patellar dislocations without osteochondral fracture.

• #26 Patellar Dislocation (Kneecap Dislocation) | Anesthesia Key

  https://aneskey.com/patellar-dislocation-kneecap-dislocation/

  After a direct blow to the medial aspect of the patella or, more commonly, without contact and only after a sudden twisting motion to the opposite side of an outward-pointing planted foot (with a powerful contraction of the quadriceps while the thigh is turning inward), the patients kneecap dislocates laterally. […] Most often, there will have been a spontaneous reduction, and the patient reports that the knee or kneecap gave way or gave out with pain and then slipped back into place. […] There are associated fractures in 28% to 50% of patellar dislocations, which can lead to degenerative arthritis. […] It must be appreciated that plain radiographs do not show a high percentage of osteochondral fractures occurring at the time of patellofemoral dislocation. […] Some authors think that anatomic predispositions, such as patella alta, trochlear dysplasia, and ligamentous laxity, play greater roles in recurrent instability.

• #27 Patella Dislocation – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK538288/

  Acute patellar dislocations typically occur as a result of trauma, usually a non-contact twisting injury to the knee, or from a direct blow to the medial aspect of the knee. A common mechanism is external tibial rotation with the foot fixed on the ground. […] Acute patellar dislocations typically occur as a result of trauma, usually a non-contact twisting injury to the knee, or from a direct blow to the medial aspect of the knee. A common mechanism is external tibial rotation with the foot fixed on the ground. Patellar dislocations can also occur in patients with generalized ligamentous laxity. However, those patients mostly tend to have recurrent subluxations of their patella as opposed to a frank dislocation. […] Patellar dislocations tend to occur in a lateral direction, partly because the direction of pull of the quadriceps muscle is slightly lateral to the mechanical axis of the limb. Medial instability is rare and more likely to result from congenital conditions, quadriceps atrophy, or iatrogenically. Intra-articular dislocation is also uncommon, but can occur following trauma where the patella is avulsed from the quadriceps tendon and is then rotated. Superior dislocations can occur in elderly patients where forced hyperextension causes the patella to lock on an anterior femoral osteophyte.

• #28 Superior Patellar Dislocation: Case Report and Comprehensive Literature Review | AOAO

  https://aoao.org/2024/08/22/superior-patellar-dislocation-case-report-and-comprehensive-literature-review/

  A knee locked in extension was the most sighted physical exam finding for superior patellar dislocation, and is important to distinguish other pathology of the knee. […] Locking often occurs as the inferior poll of the patella interlocks on the superior ridge of the infrapatellar groove. This has been reported as osteophyte formation increases the surface area of the inferior pole of the patella and the femoral ridge. This locking mechanism may be the cause of severe pain and other clinical exam findings. […] Severe pain was the second most reported clinical exam finding. […] Pain is likely caused by the inappropriate bone-on-bone articulation; as well as acute inflammation and ligament disfunction. As severe pain is not specific to superior patella dislocation it does not differentiate from other knee pathology. It does indicate that these patients have acute and significant pain and are likely to present to an emergency room, urgent care, or primary care clinic. This stresses the importance of multiple disciplinary recognition and diagnosis of this unique pathology.

• #29 Superior Patellar Dislocation: Case Report and Comprehensive Literature Review | AOAO

  https://aoao.org/2024/08/22/superior-patellar-dislocation-case-report-and-comprehensive-literature-review/

  The skin dimpling pattern of superior patella dislocation is a unique exam finding specific for superior patella dislocation. […] A skin dimple is formed when the superiorly dislocated patella inverts with the distal portion angled posteriorly applying tension to the intact patellar tendon and skin, which dimples distally. Van Egmond et al. presented that this skin dimple sign may be related to the radiographic finding of the superior poll of the patella tilting away from the femur as the intact patellar tendon is being stretched. They described this radiographic patellar tilt as being pathognomonic for a superior patellar dislocation. […] We found the most common mechanisms of injury were direct trauma and hyperextension. […] This is consistent with prior literature. Takai et al. described a patient who was able to voluntarily perform superior patellar dislocation with hyperextension from a slightly flexed position. A thorough history is vital to accurate diagnosis and differentiate the diagnosis of superior patella dislocation when a patient reports a knee injury caused by direct trauma or hypertension.

• #30 Knee Dislocation – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK470595/

  A knee dislocation can be defined as complete congruency loss between the distal femoral and proximal tibial articular surfaces. Bicruciate or multiligamentous injuries can also be categorized as knee dislocation due to the mechanism of injury. […] High-energy trauma is usually required to cause tibiofemoral dislocation at the knee joint. To disrupt this joint, multiple concomitant ligamentous injuries and instability are also expected with disruption of the knee joint. […] Knee dislocation can happen following high-energy injuries such as traffic accidents, dashboard injuries, falls from heights, and crush injuries. Low-energy injuries can also result in a knee dislocation, such as those encountered in athletic injuries or routine walking. Even ultralow-energy injuries can result in a knee dislocation in patients with morbid obesity.

• #31 How To Identify and Treat Patellar Dislocation Versus Knee Dislocation – ACEP Now

  https://www.acepnow.com/article/how-to-identify-and-treat-patellar-dislocation-versus-knee-dislocation/

  Knee dislocations involve disruption of major knee-stabilizing ligaments (medial collateral ligament, posterior cruciate ligament, anterior cruciate ligament, lateral collateral ligament, and posterolateral corner). […] The primary stabilizer ligaments of the posterolateral corner are the popliteus tendon, fibular collateral ligament, and popliteofibular ligament.

• #32 True Knee + Patellar Dislocations – Core EM

  https://coreem.net/core/true-knee-patellar-dislocations/

  Knee dislocation: Tibiofemoral dislocation defined as complete displacement of the tibia with respect to the femur, with disruption of 3 or more of the stabilizing ligaments (ACL, PCL, MCL, lateral ligament complex/LCL) […] Mechanism: Knee: Usually a high energy mechanism such as a fall from height, motor vehicle accident (dashboard injury), or high-speed athletic injury (downhill skiing). Can also be from a low-energy mechanism such as a fall from standing in the morbidly obese or a seemingly more benign sports injury such as a football tackle. […] Injury to the popliteal artery is the most feared complication and is common. […] Popliteal artery injury is the most dangerous complication with potential for downstream limb ischemia. […] 40-50% of patients with anterior/posterior dislocations will have a popliteal artery injury, due to tethering of the artery at the popliteal fossa. […] Knee dislocations are commonly complicated by popliteal artery injury. This limb-threatening complication MUST be recognized early to reduce morbidity.

• #33 Dislocated Knee Symptoms, Treatment, Recovery Time, Surgery

  https://www.medicinenet.com/dislocated_knee/article.htm

  Knee dislocations are a result of significant force or trauma. […] With a dislocated knee, the relationship between the femur and tibia is lost and at least three of four ligaments that hold the knee stable must be torn. […] A knee dislocation is a relatively rare injury. It takes significant force and energy to dislocate the knee, and at least three of the four stabilizing ligaments need to be torn to lose the relationship between the femur and tibia. […] The knee most commonly dislocates anteriorly or posteriorly, where the tibia is shoved forward or back compared to the femur. […] An associated complication is compartment syndrome. […] A knee dislocation is an orthopedic emergency and is different from a kneecap (patellar) dislocation, where the kneecap, located in front of the knee, slides laterally out of place.

• #34 How To Identify and Treat Patellar Dislocation Versus Knee Dislocation – ACEP Now

  https://www.acepnow.com/article/how-to-identify-and-treat-patellar-dislocation-versus-knee-dislocation/

  Patellar dislocation occurs when there is disarticulation of the patella bone from the patellofemoral joint. It usually occurs from low-to-moderate trauma sustained during sports or other physical activity. Risk factors for patellar dislocation include structural variants of the patella or femoral trochlea, ligamentous laxity, trauma, and connective tissue disorders. Patellar dislocations represent 3 percent of knee injuries, with a high recurrence rate ranging from 15 to 44 percent for first-time dislocations and 50 percent with a previous history of two or more dislocations. […] The mechanism in the vast majority of patellar dislocations is noncontact involving knee flexion, a valgus force with external rotation. […] Knee dislocation is a dislocation of the tibia with respect to the femur and is seen in high-energy traumas including motor vehicle accidents, falls from heights, industrial injuries, and sports injuries, as well as spontaneously in the morbidly obese during ambulation.

• #35 Patellar Dislocation | Orthopedics & Sports Medicine

  https://health.uconn.edu/orthopedics-sports-medicine/conditions-and-treatments/where-does-it-hurt/knee/patellar-dislocation/

  It has been found in retrospective studies that the incidence of recurrent dislocation after the first dislocation occurs can be as high as 40 percent. […] Surgically treating those dislocations by lessening lateral tension and tightening medial restraint could reduce this recurrence rate to below 10 percent. […] Procedures that require bone work (osteotomies) require a period of relative immobilization and need 10 to 12 weeks before a return to athletic activity is permitted.

• #36 Patella Dislocation – How Long is Recovery Time? | Jeremy Burnham, MD

  https://www.jeremyburnhammd.com/patella-dislocation-dislocated-kneecap/

  The patella, or kneecap, is a small bone that sits in front of the knee joint. […] However, sometimes the patella can become dislocated. This means that it slips out of place, usually to the outside of the knee. Patella dislocation occurs when the patella slides out of its normal position. This can happen if there is a sudden force applied to the knee, such as during a fall or car accident. […] There are many components that contribute to dislocation of the kneecap. There are bony stabilizers, such as the shape of the patella and the shape of the trochlea (the groove that the kneecap slides back and forth in). There are also soft tissue stabilizes, such as the medial patellofemoral ligament (MPFL). This ligament acts as a check rein to keep the patella from sliding too far to the outside of the knee.

• #37 The Impact of Anatomical Predisposition and Mechanism of Trauma on Dislocation of the Patella: A Retrospective Analysis of 104 Cases

  https://www.mdpi.com/2075-4426/13/1/84

  Therefore, the mechanism of trauma should be included in the process of patient assessment. […] If the mechanism of trauma is inadequate and a relevant predisposition is present, surgical therapy should be considered even after a first-time dislocation event. […] The goal of successful treatment, on the one hand, is the adequate treatment of the acute trauma effects such as osteochondral damage, on the other hand, the (re-)establishment of stable joint integrity. […] The consequences of recurrent dislocations are far-reaching, ranging from functional limitations attributed to instability, persistent pain, and reduced stress capacity of the joint, to morphological damage such as cartilage-bone pathologies with increased risk of degenerative joint disease and reduced quality of life. […] The pediatric subgroup in the trauma category “rotational trauma” also showed an increase in pathological values regarding predisposing factors compared to the adult subgroup. […] Ultimately, the surgical treatment chosen should be based on the presence of relevant predisposing factors and the resulting injuries incurred due to the dislocation event itself.

• #38 Patellar Dislocation – SportsMD

  https://www.sportsmd.com/sports-injuries/knee-injuries/patellar-dislocation-instability/

  As the athlete suffers a patellar dislocation there may be other injuries that occur within the knee joint itself. […] Factors related to the knee include poor bony development of the trochlear groove at the end of the thigh bone (femur) in which the patella normally glides. This is termed trochlear dysplasia and when present provides less than normal bony resistance to the patella dislocating. […] If the attachment of the patellar tendon to the lower leg bone (tibial tubercle) is rotated too far to the outside, there is an inherent lateral (toward the outside of the knee) pull on the patella. […] If the MPFL is deficient it can be either repaired or reconstructed with a graft. […] If the tibial tubercle is rotated too much, then it can be cut (osteotomy) and reattached with screws at an improved location. […] In the rare case where the groove for the patella (trochlear groove) is too shallow, then this may have to be addressed with surgery to make the groove deeper.

• #39 Patella dislocations | Orthopaedic Knee Specialists | Adelaide

  https://orthopaedics360.com.au/knee/patella-dislocations/

  Recurrent Patella Dislocations can lead to Arthritis. […] Patella Instability is a complex spectrum that certainly warrants a very thorough evaluation. A detailed history is taken to determine the patients symptoms and frequency of dislocations. A detailed examination is performed to assess for underlying bony and soft tissue factors that may be contributing. […] Patients who have ongoing episodes, despite initial conservative treatment, are candidates for patella realignment surgery. This involves restoring the normal gliding of the patella in its groove of the thigh bone. […] Patients who have had Instability for many years, often have cartilage damage underneath the knee cap. Surgical treatment is aimed at reducing pain.

• #40 Dislocated Knee Cap – How It Can Be Prevented? – By Dr. Deepak Kumar Arora | Lybrate

  https://www.lybrate.com/topic/dislocated-knee-cap-how-it-can-be-prevented/e528ba2c881c287e58a5d78590ff2c73

  Patella dislocation is mostly found among women and people associated with the high impact sport. It refers to a condition where the kneecap gets completely displaced from its normal location. […] Because a dislocation often damages knee tissue, the patella often remains looser, or more unstable, than it was before the injury. As a result, the patella may dislocate again. Recurrences also are common if the dislocation was caused by an irregularity in the knee structure. […] If your patella dislocates multiple times, or continues to be unstable despite therapy and bracing, surgery may be recommended to correct the problem. The type of surgery will depend on the cause of the unstable kneecap. Surgical treatments often involve reconstructing the ligaments that hold the patella in place. […] Post-surgical knee rehabilitation is a key step to a full recovery from patellar dislocation. The process of rehabilitation not only rebuilds the muscles but negate the chances of future dislocation.

• #41 Dislocated Kneecaps: What to Do When it Happens

  https://www.parkwayeast.com.sg/health-plus/article/kneecap-dislocation-children

  Kneecap dislocation in children happens more often than we think. […] A dislocated kneecap usually happens when a child falls, or takes a hit to the knee. […] But should a fall, or a hard blow to the knee happen during sports, the patella may slip out of place and get dislocated. It can be a partial or complete dislocation that is accompanied by pain and mobility issues. […] Almost 60 80% of kneecap injuries usually occur when performing a cutting/turning action while the foot is firmly planted on the ground. […] A direct blow to the knee can also cause kneecap dislocation, though this happens less frequently. […] Apart from these, inborn deformities of the thighbone, kneecap and ligamentous laxity can make your child more prone to this injury. […] Surgery is required if the patella dislocates multiple times, continues to be unstable despite treatment, or if there’s evidence of bone injury. […] The type of surgery required is guided by the injury sustained as well as the root cause. […] These are important as recurrent dislocations lead to structural damage and subsequent development of arthritis.

• #42 Patella dislocations | Orthopaedic Knee Specialists | Adelaide

  https://orthopaedics360.com.au/knee/patella-dislocations/

  Recurrent Patella Dislocations can lead to Arthritis. […] Patella Instability is a complex spectrum that certainly warrants a very thorough evaluation. A detailed history is taken to determine the patients symptoms and frequency of dislocations. A detailed examination is performed to assess for underlying bony and soft tissue factors that may be contributing. […] Patients who have ongoing episodes, despite initial conservative treatment, are candidates for patella realignment surgery. This involves restoring the normal gliding of the patella in its groove of the thigh bone. […] Patients who have had Instability for many years, often have cartilage damage underneath the knee cap. Surgical treatment is aimed at reducing pain.

• #43 Patella Dislocation – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK538288/

  Individuals with an increased Q angle are predisposed to dislocation. The Q angle is measured by drawing a line from the anterior superior iliac spine (ASIS) through the center of the patella, and a second line from the center of the patella to the tibial tubercle. Normal Q angle measurement is typically higher in females than in males, 18 degrees compared to 14 degrees. Measurements that exceed those normals predispose the patient to patellar instability. […] There are several static and dynamic stabilizers of the patella. The medial patellofemoral ligament (MPFL) is the primary static restraint to lateral patellar instability during the first 20 degrees of knee flexion. This ligament is almost always torn with patellar dislocations. The bony structure of the patellofemoral joint is another static stabilizer, especially during deeper knee flexion angles. Anatomical factors that predispose to dislocation include patella alta (high riding patella), trochlear dysplasia or lateral femoral condyle hypoplasia, and excessive lateral patella tilt. Distortion of the normal patellorfemoral joint anatomy places the patella at higher risk for instability and dislocation. The main dynamic stabilizer of the patella is the vastus medialis obliquus (VMO) muscle. This is the most distal portion of the quadriceps muscle, and exerts a medially directed pull which helps maintain the patella well positioned. Weakness or dysplasia of this muscle increases the risk for dislocations.

• #44 Traumatic Patellar Dislocation – Hughston Clinic

  https://hughston.com/wellness/traumatic-patellar-dislocation/

  During a traumatic event, such as a fall, auto accident, or sports injury, the patella (kneecap) can completely or partially dislocate. A patellar dislocation occurs when the patella jumps out of the trochlear groove (a groove that holds the patella in line) and usually moves toward the outside of the knee. […] A MPFL tear allows the patella to move out of place; and then, when it returns to its normal position, the patella damages the trochlea, causing bone bruising or fractures. […] This injury can have long-term consequences, such as instability of the patella, pain, recurrent dislocation, and patellofemoral osteoarthritis. […] Surgery would include knee arthroscopy, to look at the inside of the knee for damage, and an open procedure to stabilize the patella. This can be done with a procedure called proximal extensor mechanism realignment. This procedure takes tissue available in the knee and tightens the stretched-out structures. It also loosens tighter structures to balance the forces of the patella, and the trochlea groove it slides in.

• #45 Patellar Dislocation (Acute) | Pediatric Orthopaedic Society of North America (POSNA)

  https://posna.org/physician-education/study-guide/patellar-dislocation-(acute)

  Osteochondral injury as a result of patellar dislocation ranges from 5% to 50%, although Seeley reported an incidence as high as 73%. […] In cases in which there is a large knee effusion, aspiration may be used to improve comfort and motion recovery. […] Acute surgical treatment is performed for loose body removal or for fixation of osteochondral fractures. […] Surgical treatment is indicated in the above setting and in cases of recurrent instability. […] A consequence of recurrent patellar instability may be patellofemoral osteoarthritis. […] Overall however, recurrent instability rates are similar for nonoperative and operative management in the case of patellar dislocations without osteochondral fracture.

• #46 Patellar Injury and Dislocation: Background, Epidemiology, Functional Anatomy

  https://emedicine.medscape.com/article/90068-overview

  Patellofemoral problems are mainly diagnosed by obtaining a thorough history and performing a physical examination. Imaging studies help confirm the diagnosis. […] Patellofemoral syndromes are usually the result of biomechanical imbalances of the kinetic chain, with each individual having an optimal joint-loading limit that is dependent on his or her unique osseous and muscular anatomy, combined with the patient’s unique neuromuscular patterning. As this limit is surpassed, the patient is at risk for either acute injury, such as patella dislocation, or chronic injury, such as patellofemoral pain syndrome. Therefore, the goal of a rehabilitative treatment program is to guide the patient toward performing functional activities without surpassing his or her optimal joint-loading limit. Therapy techniques need to be designed around this principle.

• #47 Patellar Injury and Dislocation: Background, Epidemiology, Functional Anatomy

  https://emedicine.medscape.com/article/90068-overview

  The patellofemoral mechanism is very complicated. Patellofemoral malalignment, abnormal patellar configuration, and a previous history of instability increase the risk for anterior knee pain, patellar dislocation, and recurrent dislocations. The risk for symptoms increases when a combination of factors exists. […] Excluding acute patellar trauma, patellar injury and dislocation are the end result of patellofemoral force imbalances. These force imbalances may also result in less dramatic presentations of patellofemoral pain. Deformities of cartilage resulting from arthritis; congenital variants of the patellofemoral joint; imbalances in lower extremity muscular strength and/or firing pattern; skeletal imbalances at the hip, knee, ankle, or foot; and changes of the patellar stabilizing capsular and ligamentous elements may also contribute to the development of patellofemoral pain and/or dislocations.

• #48 Patellar Injury and Dislocation: Background, Epidemiology, Functional Anatomy

  https://emedicine.medscape.com/article/90068-overview

  The MPFL has been found to be the major medial soft-tissue restraint to patellar lateral displacement. Studies indicate that up to 97% of acute lateral patella dislocations result in disruption of the MPFL. […] Pain may develop in these periarticular soft-tissue structures as a result of patellofemoral dysfunction, or vice versa. All these structures operate as a functional unit to optimize weight-bearing capacity. These structures decrease joint-reaction forces (JRFs) and form a base of support for the upper body. If one of these structures is altered, a greater risk of patellar injury and dislocation can develop.

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