Review Question - QID 219912

This surgical procedure demonstrated in Figure A, is a lateral opening wedge distal femoral osteotomy, which can be employed to correct mechanical axis deviation (MAD) lateral to the center of the knee (Answer 1).

On physical examination, this patient has a widened intermalleolar distance (>8cm) and a MAD that is lateral to the center of the knee which is indicative of valgus malalignment. Additional radiographic parameters that indicate valgus malalignment include a lateral distal femoral angle (LDFA) of <85 degrees or a medial proximal tibia angle (MPTA) of >90 degrees. Correction of valgus malalignment about the knee can be achieved with a varus-producing distal femoral osteotomy, either a lateral opening wedge or a medial closing wedge.

Sherman et al. reviewed the utilization of distal femoral varus osteotomies (DFVO) in managing valgus knee deformities. The authors outline both medial closing wedge and lateral opening wedge osteotomy methods, highlighting their applications. The authors comment that the medial closing wedge osteotomy historically had more widespread use and was traditionally utilized for bilateral congenital patellar dislocations and valgus deformity. However, lateral opening wedge osteotomies have recently gained favor due to the relatively easier surgical exposure, the more accurate degree of correction, and the less complex fixation technique. They conclude that DFVO is a viable treatment option for physiologically young, active patients with lateral arthritis, valgus malalignment, or as a concomitant procedure in patients undergoing other soft-tissue stabilization, cartilage restoration, or meniscal replacement procedures.

Wylie et al. conducted a systematic review of DFVO for valgus malalignment, analyzing 16 studies with 372 osteotomies. Among these, 158 were medial closing wedge osteotomies, which had a complication rate of 13.3%, while 137 lateral opening wedge osteotomies had a complication rate of 5.1%. In the medial closing wedge osteotomy group, 55 patients underwent reoperation, mainly for conversion to arthroplasty (22%), compared to 61 patients in the lateral opening wedge osteotomy group, who primarily required hardware removal (23%). The study demonstrated an overall complication rate of about 10% and a reoperation rate of 35% to 40%. While more medial closing wedge osteotomy patients converted to arthroplasty, this is likely a function of longer follow-up for those individuals. The authors conclude that both techniques demonstrated improved patient-reported outcomes at mid- to long-term follow-up.

Figure A is an AP radiograph depicting a lateral opening wedge osteotomy with lateral locking plate fixation and allograft utilization.

Incorrect answers:
Answer 2: A MAD medial to the center of the knee would be indicative of a varus deformity and would not be surgically managed with a lateral opening wedge osteotomy
Answer 3: A LDFA of 88 degrees is within the normal range (85-90 degrees) and would not require an osteotomy
Answer 4: A LDFA of 91 degrees is indicative of a slight varus deformity and would not require a distal femur lateral opening wedge osteotomy
Answer 5: MAD that is within 7 degrees of the anatomic axis of the femur falls within the reported normal range (5-7 degrees) and would not require surgical intervention in isolation