Diagnosis
When diagnosing patellar dislocation following TKA, it is crucial to evaluate not only prosthetic alignment but also potential ruptures in medial stabilizing structures like the medial patellofemoral ligament [PMID:25264063].
Management
Anatomic MPFL reconstruction, as described in biomechanical testing [PMID:24027463], demonstrated similar lateral restraining force compared to the intact MPFL at 1 and 5 mm of lateral displacement and significantly increased force at 10 mm, suggesting improved patellar stability post-reconstruction.
In this case report, medial patellofemoral ligament reconstruction combined with lateral retinacular release was successfully employed to address patellar dislocation post-TKA caused by medial structure rupture [PMID:25264063].
Twenty-one patients underwent MPFL reconstruction respecting the distal femoral physis, resulting in no recurrent dislocations postoperatively [PMID:23111806].
Complications
Given the high incidence of recurrent instability with conservative management [PMID:24027463], MPFL reconstruction offers a biomechanical advantage that could mitigate this complication, though clinical outcomes requiring direct comparison are not detailed in this study.
The paper highlights that patellar dislocation after TKA can result from the rupture of medial structures, emphasizing this as a specific complication requiring targeted surgical intervention [PMID:25264063].
Two patients with high-grade trochlear dysplasia still exhibited a positive apprehension sign postoperatively, suggesting unresolved instability issues [PMID:23111806].
Prognosis & Follow-up
While the study [PMID:24027463] focuses on biomechanical outcomes, the enhanced stability provided by MPFL reconstruction suggests potential for better long-term prognosis and follow-up stability outcomes compared to non-surgical interventions.
The study reported a significant improvement in the Kujala score postoperatively, indicating enhanced knee function [PMID:23111806].
References
1 Duchman KR, DeVries NA, McCarthy MA, Kuiper JJ, Grosland NM, Bollier MJ. Biomechanical evaluation of medial patellofemoral ligament reconstruction. The Iowa orthopaedic journal 2013. link 2 Goto T, Hamada D, Iwame T, Suzue N, Takeuchi M, Egawa H et al.. Medial patellofemoral ligament reconstruction for patellar dislocation due to rupture of the medial structures after total knee arthroplasty: a case report and review of the literature. The journal of medical investigation : JMI 2014. link 3 Nelitz M, Dreyhaupt J, Reichel H, Woelfle J, Lippacher S. Anatomic reconstruction of the medial patellofemoral ligament in children and adolescents with open growth plates: surgical technique and clinical outcome. The American journal of sports medicine 2013. link