Physical examination of the patellofemoral joint

Patients with a patellofemoral pain are either in an acute state after a patellofemoral dislocation or are suffering from a chronic anterior knee pain (AKP), whereas AKP might be accompanied by patellar instability without dislocation. Whereas the acute state after a dislocation is mostly clear and its examination limited, the examination of a AKP is much more complex. A profound knowledge of the anatomy, the painful structures and patellofemoral biomechanics is essential in order to find the underlying pathology within the heterogeneous and diverse etiologies. Furthermore, a meticulous and precise examination is key to find the adequate treatment for AKP.

Physical examination of the patellofemoral joint

Patients with a patellofemoral pain are either in an acute state after a patellofemoral dislocation or are suffering from a chronic anterior knee pain (AKP), whereas AKP might be accompanied by patellar instability without dislocation. Whereas the acute state after a dislocation is mostly clear and its examination limited, the examination of a AKP is much more complex. A profound knowledge of the anatomy, the painful structures and patellofemoral biomechanics is essential in order to find the underlying pathology within the heterogeneous and diverse etiologies. Furthermore, a meticulous and precise examination is key to find the adequate treatment for AKP.

Patellar Tendon–Lateral Trochlear Ridge Distance: A Novel Measurement of Patellofemoral Instability

Background: Abnormalities in the trochlea-patella-tibia relationship have been shown to be risk factors for recurrent patellofemoral instability, although no current measurements quantify patellar containment in the trochlea. Standard measurements, such as tibial tubercle–trochlear groove (TT-TG) distance, do not account for the containment of the patella by the trochlea. Our goal was to develop a measurement to assess how well the trochlea contained the extensor mechanism. Hypothesis: A novel measurement describing the amount of the patellar tendon lateral to the lateral trochlear ridge (PT-LTR) would be a reliable measurement and significantly greater among patients with patellofemoral instability. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The authors analyzed radiology records from 2005 to 2014 for patients aged 5 to 18 years with and without patellofemoral dislocations who had knee magnetic resonance imaging (MRI). Two blinded reviewers evaluated 215 MRI studies. Standard and novel morphology measurements were calculated for each knee and compared in a case-control design. Interobserver reliability of each measure was assessed by the intraclass correlation coefficient. Predictability for patellofemoral dislocation was calculated with 2-tailed independent-samples Student t tests. Discriminative capacity was calculated with receiver operating characteristic analyses and area under the curve (AUC). An optimal measurement cutoff with resultant sensitivity and specificity was calculated. Results: Standard measurements of TT-TG distance, tangential axial width of the patella (TAWP), and tangential axial trochlear width (TATW) had excellent agreement between raters; lateral femoral condyle length had good agreement; and the novel measurement—width of the tendon beyond the lateral femoral condyle (PT-LTR)—also had excellent agreement. These underwent predictability and discriminative capacity analyses. TT-TG, TAWP, TATW, and PT-LTR were significant predictors of patellofemoral instability. In receiver operating characteristic analysis, TAWP had an AUC of 0.65, below the 0.8 threshold. TATW had an AUC of 0.814 and, when <32.5 mm, was 76% sensitive and 77% specific for dislocations. TT-TG demonstrated an AUC of 0.806. TT-TG ≥13.5 mm was 76% sensitive and 76% specific for dislocations. PT-LTR demonstrated an AUC of 0.876 and, when ≥5.55 mm, was 73% sensitive and 89% specific for patellofemoral dislocation. Conclusion: PT-LTR is reliable, predictable, and discriminative for patellofemoral dislocations. This measurement had sensitivity similar to that of TT-TG but with higher specificity.

Medial Patellofemoral Ligament Double Avulsion in a Collegiate American Football Athlete: A Case Report

An 18-year-old male collegiate American football player with no previous medical history of knee injury suffered an acute left patellofemoral dislocation during preseason practice. Diagnostic imaging and exploratory surgery revealed multiple avulsions of the medial patellofemoral ligament as well as significant lateral patellar tilt and chondromalacia of the left patella. A surgical repair of the ligament was performed as well as a lateral release and debridement of multiple structures. With no rehabilitative protocols available for multiple avulsion repair, a protocol for a single avulsion repair of the medial patellofemoral ligament was used with some exceptions. The patient returned to full-contact American football activities at 5 months postoperation with no reported complications. These findings indicate that a rehabilitation protocol for single avulsion repair may be appropriate for multiple avulsions as well.

Medial Patellofemoral Ligament Reconstruction

Objectives: Recurrent patellofemoral dislocation is usually a multifactorial pathology. Different surgical techniques have been described according to the etiology of dislocation. In absence of a severe malalignment or an anatomical patellofemoral dysplasia, reconstruction of Medial Patello-femoral Ligament (MPFL) can restore the normal tracking of the patella, avoiding lateral excursion. The purpose of this study was to evaluate clinical results and complications in patients who underwent a MPFL reconstruction. Methods: We retrospectively evaluated 19 patients who underwent an anatomic MPFL reconstruction using autologous semitendinosus graft between 2007 and 2012. Exclusion criteria were patients with less than three years of follow-up and those with an associated procedure such as distal realignment or trochleoplasty. Clinical outcomes were measured using Kujala score and return to sport rate. We registered the postoperative complications and recurrence rate. Results: Nine patients were men and 10 women with a mean age of 25 years. Average follow-up was 5.8 years. Nine patients (47.4%) returned to their previous sport level, 8 (42.1%) changed to another sport or decreased their level and 2 (10.5%) were unable to practice any sports at all. Kujala score improvement was from 62.8 preoperative to 88.8 postoperative. One patient decreased the Kujala score. Eighty-nine percent of patients were satisfied with their outcome. One patient had a patellar fracture and four developed an arthrofibrosis and required mobilization under anesthesia. No recurrences were registered. Conclusion: Isolated MPFL reconstruction for recurrent patellofemoral dislocation is an effective alternative in absence of severe malalignment or anatomical dysplasia. Although no recurrences where registered at minimum 3-year follow-up, almost half of the patients were not able to return to their previous sport level.