Diagnosis and treatment of excessive lateral pressure syndrome of the patellofemoral joint caused by military training

Abstract

Objective: To investigate the diagnosis and surgical treatment of excessive lateral pressure syndrome of the patellofemoral joint caused by military training.

Methods: Fifteen patients (patient group) and 18 healthy volunteers (control group) were involved in this retrospective study. Radiographs of the knee joints of all patients and volunteers were taken. The bone architecture was assessed, the trochlear angle, coincidence angle and patellofemoral joint index measured in both groups, and the resulting data compared. All 15 patients (17 knees) were treated by lateral collateral retinaculum release. Pre- and post-operative pain was evaluated with a visual analog scale (VAS).

Results: The differences between the two groups in coincidence angle (patient group: 7.67°± 5.81°; control group: -2.2°±-2.71°) and patellofemoral joint index (patient group: 2.49 ± 1.40; control group: 1.25 ± 0.15) were statistically significant. Subchondral bone sclerosis and osteophytosis in the patellofemoral joint were more pronounced in the patient group than in the control group. The VAS was higher preoperatively (7.06 ± 0.85) than postoperatively (6 months postoperatively: 3.87 ± 0.24; 1 year postoperatively: 3.01 ± 0.17), and the differences between preoperative and postoperative were statistically significant.

Conclusions: Apart from the case history, typical symptoms and physical signs, X-ray examination is the most basic way to diagnose excessive lateral pressure syndrome of the patellofemoral joint, and the patellofemoral joint index is the most reliable for diagnosis. Lateral collateral retinaculum release with a small-incision is an effective treatment for this disease.

Figure 1

Trochlear angle and coincidence angle. The trochlear angle ¹ , ² : on an X‐ray film of the patellar axis, the trochlear angle is formed by the combination of two lines. The first line (AB) runs from the highest point of the inner side of the angle of the thighbone to the thighbone trochlea; the other one (BC) runs from the highest point on the outer side of the angle of the thighbone to the thighbone trochlea, thus angle ABC is the trochlear angle. Coincidence angle ¹ , ² : this is formed by drawing the bisector BE of the trochlear angle, and then drawing a line BD from the vertex of the trochlear angle to the lowest point of the patellar ridge, thus angle DBE is the coincidence angle. If the lowest point of patellar ridge falls outside the bisector, the coincidence angle is positive; if not, it is negative. The coincidence angle shows the relationship between the patella and the thighbone trochlea.

Figure 2

Patellofemoral joint index. Patellofemoral joint index ¹ , ³ : the ratio of the lengths of the medial interspace (CD) and lateral interspace (AB) of the patellar joint (i.e. CD/AB). Normally, the medial interspace of the patella joint is bigger than the lateral interspace. An increase in the patellofemoral joint index means that the medial interspace of the patellar joint gets wider, and this shows that the patella is inclining outward.

Figure 3

X‐ray film of the knee joint of one patient. Subchondral bone sclerosis and osteophytosis at the lateral edge of the patellofemoral joint can be seen.