Patellofemoral Joint after Opening Wedge High Tibial Osteotomy: A Comparative Study of Uniplane versus Biplane Osteotomies

Abstract

Objective To the best of our knowledge, there has been no comparative study of changes in radiographic parameters in the sagittal plane between biplane opening wedge high tibial osteotomy (OWHTO) with plate fixation and uniplane OWHTO with spacer implantation. The aim of the study was to compare sagittal radiographs between the procedures of biplane and uniplane OWHTOs in patients with genu varum and to investigate the impact on the patellofemoral joint. Methods A retrospective study of 71 patients (58.0 ± 5.0 years of age, 58 females and 13 males) with varus‐aligned medial compartment knee osteoarthritis treated with OWHTO was performed during the period from January 2016 to February 2019. Thirty‐three patients underwent biplane osteotomy with plate fixation (biplane group), and 38 patients underwent uniplane osteotomy with absorbable wedged spacer fixation (uniplane group). Independent t tests were used to compare the two groups according to the preoperative and postoperative radiographic parameters of hip‐knee‐ankle (HKA) angle, posterior tibial slope (PTS), tibial tubercle prominence (TTP), Caton–Deschamps (CD) index, and Blackburne–Peel (BP) index. During the last follow‐up assessment, patients were asked to rate their patellofemoral joint status using the Samsung Medical Center (SMC) patellofemoral (PF) scoring system. The visual analog scale (VAS) was also used to rate knee joint pain when walking. Results There was no significant difference between the two groups in any of the demographic, clinical, or radiological characteristics at baseline (p > 0.05). Comparisons of postoperative sagittal radiographic parameters between patients in the uniplane group and patients in the biplane group showed significant differences in the PTS (13.4° vs 16.6°, t = 4.465, p < 0.001), TTP (9.0 mm vs 4.2 mm, t = 7.950, p < 0.001), and CD index (0.81 vs 0.70, t = 4.035, p < 0.001). At the final follow‐up assessment (minimum, 2 years), the SMC PF function score was significantly lower in patients in the uniplane group than in patients in the biplane group (27.8 vs. 32.1, t = 2.458, p = 0.016), but there were no significant differences in the SMC PF pain score or VAS score (p > 0.05). Conclusion The essential difference in the postoperative sagittal radiographic changes between biplane and uniplane OWHTO was the tibial tubercle prominence, indicating the posterior displacement of the tibial tubercle. Uniplane OWHTO may yield better function of the patellofemoral joint compared to biplane OWHTO.

Difference in the anterior displacement of the tibial tuberosity relative to the proximal tibial fragment between opening wedge and closed wedge high tibial osteotomies

“…In the present study, the AP displacement of the osteotomized fragment was defined The values are given as mean ± standard deviation.AP: anteriorposterior, TT: tibial tuberosity, FTA: femoral tibial angle, PTS: posterior tibial slope, mBPI: modified Blackburne-Peel index, mCDI: modified Caton-Deschamps index. biplane ascending osteotomy showed more rearward movement of the TT from the proximal fragment than the uniplane osteotomy [23]. Although they reported good reproducibility of the measuring method, it may be potentially affected by the change in PTS.…”

“…In addition to these changes in the sagittal plane, a few studies showed a change of the osteotomized fragment in the AP direction after HTO, i.e. in OWHTO, the TT is not only moved to the distal direction but also moved to the posterior direction in relation to the biplane osteotomy [23]. No comparative study has been conducted to assess changes in the AP direction of the distal fragment in relation to the proximal fragment between OWHTO and CWHTO, and the present study focused on it.…”