Patellar dislocation

Content

1. Search strategy
2. Definition
3. Clinically relevant anatomy
4. Epidemiology and etiology
5. Characteristics and clinical presentation
6. Differential diagnosis
7. Diagnostic procedures
8. Outcome measures
9. Examination
10. Medical managment
11. Physical therapy managment
12. Key research
13. Clinical bottom Lines
14. Recent released research
15. References

Search Strategy

The first step of my search strategy was consulting the medical library of the university. Then I searched the databases online for articles relevant for this subject like; pubmed, Pedro an web of knowledge. On this websites I used keywords like: patella, managment, dislocation and human.

Definition

A luxating patella or patellar dislocation is a severe acute injury where there is a shift of the patella. Because of this shift the patella will leave the patellofemoral groove.

Clinically relevant anatomy

The patellofemoral joint is the portion of the knee joint between the patella and the femoral condyles. The patellofemoral articulation totally depends on the function of the quadriceps. It increases the angle of pull of the patellar tendon, improving the mechanical advantage of the quadriceps in knee extension. ( 1,11 )

The articular surfaces consist of the patella and the trochlear surface of the femoral condyles. The articular cartilage on the medial facet is thicker than on the lateral facet, with the lateral facet bigger than the medial. ( 2 )

The femoral condyles only project slightly in front of the shaft of the femur but project quite a distance posteriorly. The anterior aspects of both condyles are included in the articular area of the patella. The patellar articular surface is larger on the lateral femoral condyle than on the medial. There is an anterior projection on the lateral femoral condyle lateral to the patellar groove. This is the bony factor, which prevents lateral dislocation of the patella. The trochlea is on the anterior, distal end of the femur. The groove is continuous posteriorly with the intercondylar notch of the femur. The lateral facet is more prominent and has a greater radius. ( 5, 12 )

The suspension and movement of the patella is provided by passive and active stabilizers. • Passive: fascia lata, ligamentum patellae, capsule of the knee, ligamentum patellofemorale medial and lateral and ligamentum meniscopatellare medial and lateral • Active: the four heads of the quadriceps, ligamentum patellae and the retinacullum ( 1 )

Epidemiology and etiology

Athletics are often associated with patellar dislocation ( Ficat ’77, Hugston ’84 ). It is most common in females in the second decade of life. (4)

Patellar dislocation most often result results from a non-contact injury to the knee. It’s etiology is regarder as multi-factorial, being associated with: reduced osseous constraint form the lateral femoral condyle; an imbalance between stronger lateral tissues, such as the lateral retinacullum and vastus lateralis, which are able to overcome weaker medial structures, especially the medial patellofemoral ligament and the distal vastus medialis; and finally biomechanical issues such as femoral and tibial rotation, and pes planus.

The typical mechanism of injury is a twist of the leg, with the femur rotating internally on a fixed foot and tibia. Valgus stress is often associated with this rotating mechanism, thereby creating a strong laterally directed force, dislocating the patella ( Hugston ’84 ). A direct blow as well to the lateral side of the knee, producing a valgus stress, as to the medial side of the knee producing a direct dislocating force can also create this injury ( Fu ’90 ).(3)

A knee tape with a lateral reinforcement will reduce the movement of the patella so that can be used as prevention. (4)

Characteristics and clinical presentation

The patella almost always dislocates laterally. The patient may notice the patella sitting laterally, or might say that the rest of the knee shifted medially. It is unusual to see dislocation of the patella except at the time of injury. Reduction occurs when the knee is extended.(6)

The patient will experience pain, instability of the knee and blocking of the knee after the trauma. After de dislocation there will be a swelling on the medial side of knee because on this side a lot of tissue will be hit.(4)

Differential diagnosis

A radiography to exclude osteochondral fractures and avulsion fractures, patellar apprehension test is also needed, where the patella will provide resistance, patella tracking assessment.(4,6,7)

Diagnostic procedures

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Outcome measures

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Examination

This is recommended to determine whether there are predisposing factors for dislocation, such as patella alta, genu recurvatum, increased Q angle and patellar hypermobility (3,4,7)

Medical managment

Immediately after the trauma there is an immobilization in a cylinder cast for 6 weeks and medication, supplements like glucosamine and NSAID’s that could be used to keep the knee strong. If required arthroscopy with or without retinacular repair, surgical repair of the torn retinacullum or immediate patellar realignment. (3,6,8,9,10)

Physical therapy management

Conservative treatment have included : ( 3,4,10 )

• Manuel therapy and mobilization exercises to improve the ROM of the knee
• Electrotherapy
• Strengthening exercises for quadriceps, hamstrings, adductors, muscles of the hip and lower abdomen. Important, is the use of closed kinetic chain exercises because of a greater number of advantages over the other forms of exercise.
• Stretching and flexibility training for hamstrings and quadriceps
• Proprioceptive exercises to improve the stability of the knee

Bracing and re-education can play an important role in the treatment and prevention of patellar dislocation. ( 9 )

Clinical bottom Lines

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References

1. D.L. Egmond, R. Schuitemaker. De knieregio. In: A.J.F. Mink, H.J. ter Veer, J.A.C.Th. Vorselaars. Extremiteiten manuele therapie in enge en ruime zin. 1e uitgave. Houten. Bohn Stafleu Van Loghum bv. 2006. p. 559 – 628 Level of evidence: D 2. Omer Matthijs, Didi van Paridon-Edauw, Dos winkel. Hoofdstuk 2 knie. Manuele therapie van de perifere gewrichten. 1e uitgave. Houten. Bohn Stafleu Van Loghum bv. 2004. p. 220 – 235 Level of evidence: D 3. Harry B. SKinner, Robert L. Barrack, Michael S. Bedmar, George D. Clarson et al. Sports medicine. In: Shelley Reinhardt, Isabel Nogueira, Peter J. Boyle. Current diagnosis en treatment in orthopedics. 2e edition. United states of America. McGraw-Hill. 2000. p. 125 – 175 Level of evidence: A2 4. R. meeusen. 2011. Praktijkgids knieletsels. Cursus. Vrije universiteit brussel. Level of evidence: D 5. G.VD. Bijl Jr., C.G. De Graaf, P.A. De Ridder. “hoofdstuk”. Actief en passief bewegen in de gewrichten der extremiteiten. De tijdsstroom. 1975. p. 126 Level of evidence: A1 6. Pierre-paul Castelyn. “hoofdstuk”. Acute knee injuries, diagnostic and treatment managment proposals. Vub University press. 2001. p. 42-43 Level of evidence: A1 7. Karen S. Beeton. The knee. Manual therapy masterclass: the peripheral joints. Churchill livingstone. Elsevier. 2003. p. 54 – 55 Level of evidence: A2 8. Smith TO., Davies L., Chester R., Clark A., Donell ST. CLinical outcomes of rehabilitation for patients following lateral patellar dislocation: a systematic review. Phystiotherapy. Volume 96. Issue 4. December 2010. p. 269 – 281 Level of evidence: A1 9. Toby O. Smith et al. A national survey of the physiotherapy managment of patients following first time patellar dislocation. Physiotherapy. Volume 97. January 2011. p. 327 – 338 Level of evidence: A2 10. Anderson MK., Hall SJ. Sports injury managment. Lower limb injuries. Baltimore, Md: Williams & Wilkins. 1995 Level of evidence: C 11. Plastanga N., Field D., Soames R. Anatomy and human movement. Oxford. Butterworth-Heinnermann. 1990 Level of evidence: C 12. Human kinetics Publisher. Clincal anatomy of the patellofemoral joint. International sportsmedicine journal. 2001. http://www.ismj.com Level of evidence: D