Patello-femoral pain syndrome

Patellofemoral joint forces and stress during forward step-up, lateral step-up, and forward step-down exercises

STUDY DESIGN

Controlled laboratory study using a repeated-measures design.

OBJECTIVE

To quantify patellofemoral joint reaction force (PFJRF) and stress (PFJS) during forward step-up (FSU), lateral step-up (LSU), and forward step-down (FSD) exercises.

BACKGROUND

Although FSU, LSU, and FSD exercises are commonly used in patellofemoral joint rehabilitation programs, the influence of these stepping tasks on patellofemoral joint kinetics has not been quantified.

METHODS

Three-dimensional lower extremity kinematics and kinetics and electromyographic (EMG) data were obtained from 20 healthy adults during their performance of FSU, LSU, and FSD exercises. The step height for each participant was adjusted to permit a standardized knee flexion angle of 45°. A previously described biomechanical model of the patellofemoral joint was used to quantify PFJRF and PFJS during each task. Peak PFJRF and PFJS during the concentric and eccentric phases of each step task were compared using a 2-factor analysis of variance (ANOVA).

RESULTS

When collapsed across concentric and eccentric phases, peak PFJS was significantly greater during the FSD (mean ± SD, 13.8 ± 0.4 MPa) compared to the LSU (11.5 ± 0.8 MPa; P<.001) and FSU (11.2 ± 0.6 MPa; P = .002) exercises. Peak PFJRF also was significantly greater during the FSD (51.1 ± 2.7 N/kg) compared to the LSU (44.1 ± 3.4 N/kg; P<.001) and FSU (43.6 ± 2.3 N/kg; P = .023) exercises.

CONCLUSION

In selecting exercises that promote lower extremity muscle strengthening while minimizing patellofemoral joint loading, LSU and FSU should be considered over FSD exercises, if the same step height is used.

Combined lateral retinacular release with drilling chondroplasty for treatment of patellofemoral osteoarthritis associated with patellar malalignment in elderly patients

This paper described a less invasive surgical technique that was performed for treatment of elderly patients with isolated patellofemoral (PF) osteoarthritis (OA) associated with patellar malalignment, although their tibiofemoral joints are minimally osteoarthritic. Two hundred and thirty-four knees in 126 consecutive elderly patients (average, 72 yrs) diagnosed with combined disorders were treated by lateral retinacular release with drilling chondroplasty. The inclusion criteria were patient age ≥ 65 yrs, isolated stage 2 or 3 PF-OA (modified Iwano staging by radiology), and a laterally subluxed patella shown on a Merchant's axial radiograph. Outcome was judged by three parameters: clinical PF function (modified Kujala scoring), congruence angle, and PF-OA staging. Two hundred and one knees in 107 patients were followed-up for an average of 4.2 yrs (range, 2.1-7.5 yrs) and 19 patients were lost to follow-up. No surgical complications occurred through the course of treatment. Clinical PF function improved in knees that showed unsatisfactory performance (modified Kujala scoring < 32) preoperatively, with 78.1% of the knees showing satisfactory performance (modified Kujala scoring ≥ 32) at the latest follow-up. Congruence angle improved in 85.6% of the knees and PF-OA staging improved in 77.1% of the knees. Combined lateral retinacular release with drilling chondroplasty is a feasible alternative for treatment of PF-OA associated with patellar malalignment in elderly patients where knee arthroplasty cannot be performed by various reasons. Advantages of this combined surgical technique include a less invasive procedure, minimal complication rate, and an acceptable success rate (78%, modified Kujala scoring≥32).