Prediction and Development of Preventive Strategies for Lateral Hinge Fracture During Opening Wedge High Tibial Osteotomy Based on Osteotomy Configurations

Abstract

Background: Lateral hinge fracture (LHF) is a major complication of opening wedge high tibial osteotomy (OWHTO) and may result in poor outcomes. Purpose/Hypothesis: The purpose of this study was to develop preventive strategies by identifying factors that affect LHFs. We hypothesized that (1) each LHF type would have different affecting factors and that (2) specific operative strategies that can contribute to the prevention of each LHF type can be developed. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively analyzed 261 consecutive knees treated with biplanar OWHTO between March 2014 and December 2017. Perioperative radiological variables that can affect LHFs were measured and divided into 2 categories: unmodifiable and modifiable. A regression model was developed, and subgroup analyses involving comparisons between the non-LHF group and each LHF group were performed. The weightbearing line (WBL) ratio was measured at 2 weeks and 1 year after surgery to determine the serial changes in each LHF type. Results: A total of 66 knees (25.3%) were diagnosed with LHFs. From these, 26 (39.4%), 13 (19.7%), 15 (22.7%), and 12 (18.2%) showed type I, II, III, and I-variant LHFs, respectively. In the subgroup analysis, a larger posterior gap and distance X and a smaller fibular height (FH) were significant unmodifiable factors, while the retrotubercular thickness was a significant modifiable factor, for type I LHF. For type II LHF, a smaller lateral condylar slope and a larger distance X were significant unmodifiable factors, while the lateral distal fragment thickness and the osteotomy-condylar angle were significant modifiable factors. For type III LHF, a larger lateral condylar width and distance X and a smaller FH were significant unmodifiable factors, while the lateral proximal fragment thickness and the retrotubercular angle (RA) were significant modifiable factors. A smaller FH and a larger distance X were significant unmodifiable factors for type I-variant LHFs, while the lateral thickness ratio and the RA were significant modifiable factors. Between postoperative week 2 and 1 year, the WBL ratio decreased in cases with type I LHFs ( P < .001) and increased in those with type II ( P = .001) and type I-variant ( P = .006) LHFs. Conclusion: Unmodifiable and modifiable factors for the development of LHFs after OWHTO differ among LHF types. To prevent LHFs, the causes of each LHF must be identified, the patient’s specific geometry be considered in the preoperative planning, and the surgical technique be modified according to the modifiable factors. In addition, during the rehabilitation period after OWHTO, specific caution and close observation are necessary for alignment changes related to each LHF type.

Factors Associated With Unfavorable Radiological Outcomes After Opening-Wedge High Tibial Osteotomy for Varus Knees

“…16,17,22 An LHF has been reported as an important factor associated with inaccurate correction and recurrence. 5,19,34 In the subgroup analysis of unfavorable radiological outcomes, DWBLR was the common significant factor associated with unfavorable radiological outcomes, except for a JLCA <0 and an LHF. For a JLCA <0 , which indicates a tendency for valgus overcorrection, only the JLCA parameters were significant.…”

“… 16 , 17 , 22 An LHF has been reported as an important factor associated with inaccurate correction and recurrence. 5 , 19 , 34 …”

“…Unfavorable radiological outcomes were based on previously reported parameters and were categorized as follows: (1) MPTA >95°, 7 , 13 , 15 , 30 (2) JLCA >4° (insufficient medial release), 11 , 16 , 33 (3) JLCA <0° (medial instability), 16 , 17 , 22 (4) recurrence of a varus deformity, 18 and (5) LHF. 5 , 19 , 34 The recurrence of a varus deformity was defined as a WBLR <55% on whole-leg radiographs at 1 year after surgery because our target point for the WBLR was adjusted as 55% to 65% (∼62%) according to the status of the medial compartment of the knee joint. All patients were also classified into 2 groups (unfavorable outcomes and favorable outcomes) according to the presence of unfavorable radiological outcomes, and comparisons were performed between them.…”

Predictive Factors for Lateral Hinge Fracture in Medial Closing Wedge Distal Femoral Osteotomy

“…Lee et al 13 reported that the coronal osteotomy slope was significantly larger in the LHF group than in the non-LHF group (20.3°± 5.1° vs 16.7°± 4.2°, respectively; P = .001). Choi et al 4 also reported that coronal osteotomy angle was one of the significant modifiable factors to prevent LHF in MOHTO. Lee et al 13 explained that if osteotomy is performed with an abrupt angle on the coronal plane in MOHTO, the thickness of the posterolateral bony bridge would be reduced and the risk of developing LHF would be increased.…”

Precise Patellar Tendon Insertion Protection and Osteotomy Surface Advantage of Transtibial Tuberosity–High Tibial Osteotomy

“…The angle of the osteotomy line is increased because the osteotomy line is moved down to avoid the insertion point of the patellar tendon. An increase in the osteotomy line angle can also reduce the risk of type II fracture 35 . Although the distance between the tibial plateau and the crown of the fibula was 9.4 ± 2.8 mm, 36 because neither the bone knife nor the K‐wire penetrated the lateral cortex, the superior tibiofibular syndesmosis was not damaged by the surgical procedure.…”