Gait Improvement After Distal Femoral Osteotomy for Permanent Patellar Dislocation Following Femoral Lengthening in an Adolescent With Achondroplasia: A Case Report

In patients with skeletal dysplasia, certain disease-specific and treatment-related characteristics may affect functional outcomes following orthopedic surgery. We report a case of valgus deformity with permanent patella dislocation after femoral lengthening treated with distal femoral osteotomy (DFO), in which improvement in gait ability was achieved during the postoperative rehabilitation course. A 15-year-old Japanese boy with achondroplasia (ACH) had undergone tibial and femoral lengthening. During the femoral lengthening, valgus deformity and the accompanying permanent patella dislocation on both sides appeared; therefore, a staged bilateral knee osteotomy was scheduled. The preoperative status included a decreased walking speed of 0.68 m/s with a requirement for crutches. The surgery was performed bilaterally with a six-week interval and included DFO, lateral retinacular release, and medial patellofemoral ligament (MPFL) reconstruction. After a six-week non-weight-bearing period in each limb, the patient was able to walk independently with crutches; however, lateral asymmetry and lack of bimodal pattern, in addition to a decreased speed of 0.60 m/s, were noted by gait analysis. Additional rehabilitation programs, including gait training using real-time feedback of absolute load, were implemented to increase lower-limb loads and normalize the gait cycle. After a further nine weeks of inpatient rehabilitation, improvements in lateral asymmetry and load pattern were observed with a speed of >1.0 m/s without a walking aid. These results highlight that perioperative rehabilitation combined with DFO can effectively improve physical function in ACH patients with severe functional impairments and characteristic limb deformities.