The patellofemoral joint – often forgotten, ­erroneously unconsidered or simply misunderstood? – Editorial 1/2020

Tscholl PM
Department of Orthopedics and Traumatology, University Hospital of Geneva, Switzerland

Up to 40% of all athletes suffer from patellofemoral disorders every season, with a high prevalence of 15-25% especially in pivoting sports [1]. It has a high risk of recurrence, might persist for a prolonged time and therefore considerably influence the athlete’s trainability and performance over his career. Exercise-related, peripatellar pain is the most frequent observed condition and usually described as anterior knee pain (AKP), or synonymously called patellofemoral pain syndrome (PFPS). The formerly used term “chondromalacia patellae” has been shown to be misleading, and is no longer used in literature. Traumatic and non-traumatic lateral patellar dislocation is comparatively rare, however, AKP in between two episodes of patellar dislocation or after successful stabilization surgery the most frequent symptom [2].
The more precise diagnosis is most frequently attributed to the painful anatomical structure and relies on clinical history and palpation; proximal patellar tendinopathy (Jumper’s knee) for pain at the tip of the distal patella, distal iliotibial tract friction syndrome at the lateral femoral epicondyle (Runner’s knee), Morbus Osgood Schlatter in adolescents or a recurrent painful ossicle at the tibial tubercle in adults, a painful lateral retinaculum usually found in the lateral patellar hypercompression syndrome with or without degenerative cartilage lesions, painful medial patellar plica, and in some cases tendinopathy of the pes anserinus. This variety of anatomical structures potentially being painful in isolation or combination with each other, makes AKP or PFPS rather a vague and indistinct description of symptoms and should therefore be avoided.
Since a symptomatic proximal patellar tendon or lateral retinaculum rarely result from a local overuse or direct trauma only, but almost always are present in combination with other causes that trigger and sustain the painful condition, the understanding and diagnostics of these underlying causes by means of patient’s history, clinical examination and imaging, is mandatory for successful treatment [3,4]. Treating these underlying causes are by far more important than focusing the painful anatomical structure itself. Rogan et al [5] propose therefore a categorization of the different causes for AKP based on structural and functional deficits as follows: 1) a structural overload due to simple overuse, 2) a relative overload due to functional lower limb malalignment with or without a related triggering factor, 3) patellofemoral malalignment (comprising patellofemoral dysplasia, anomalies of the femoral and tibial torsion and coronal lower limb alignment) with consecutive patellar maltracking or 4) patellar instability with or without patellar dislocation.
I hope, that the following articles will help you to improve your understanding of the painful anatomical structure around the patella in combination with the underlying causes of AKP to tailor a multimodal and personalized treatment plan, and to give insight of the potential treatment options of the instable and painful patella.

Corresponding author

Philippe M. Tscholl
Centre de médecine de l’appareil
locomoteur et du sport
Rue Gabriel-Perret-Gentil 4
1205 Genève
Tel: +41 22 727 15 50
Email: Philippe.Tscholl@hcuge.ch

References

1. Foss KB, Myer GD, Chen SS, et al. Expected prevalence from the differential diagnosis of anterior knee pain in adolescent female athletes during preparticipation screening. J Athl Train. 2012;47:519-524.

2. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med. 2012;40(8):1916-1923.
3. Furrer PR, Laux CJ, Fucentese SF, Tscholl PM. Physical examination of the patellofemoral joint. Swiss Sports & Exercise Medicine. 2020; 68(11):6-12.
4. Hamard M, Boudabbous S, Tscholl PM. What sports medicine practitioners should know about imaging for femoro-patellar pathologies. Swiss Sports & Exercise Medicine. 2020;68(11):13-19.
5. Rogan S, Taeymans J, Clijsen R, Lutz N, Tscholl PM. Konservative Behandlungsstrategien patellofemoraler Beschwerden. Swiss Sports & Exercise Medicine. 2020;68(11):28-33.