The effect of the distance between the end point of the osteotomy and the lateral cortex on the lateral cortical hinge fracture in medial opening-wedge high tibial osteotomy

Prediction of Fractures After Open Wedge High Tibial Osteotomy Based on the Distance From the Tibial Osteotomy Point to the Medial Edge of the Tibia

BACKGROUND

To investigate the relationship between the distance from the medial tibial osteotomy point to the medial tibial edge and the development of lateral tibial hinge fracture (type II) and intra-articular tibial plateau fracture (type III) in patients who have degenerative disease undergoing open wedge high tibial osteotomy (OWHTO). This information will aid surgeons in avoiding the occurrence of fractures.

METHODS

This retrospective study analyzed 304 patients who underwent OWHTO from January 2018 to January 2024 in the Affiliated Hospital of Qingdao University. The distance from the tibial osteotomy point to the medial tibial edge on imaging was analyzed to determine its association with fracture. A one-way analysis of variance was used to compare the differences in height, weight, body mass index, the distance from the medial tibial osteotomy point to the medial tibial edge, sex, left and right sides of the knee, and osteoporosis in the occurrence of types II and III fractures. Receiver operating characteristic curves were used to identify the critical distances associated with type II and type III fractures. Logistic regression analyses were used to obtain the OR of the critical distance adjusted for age, sex, left and right sides, body mass index, and T value.

RESULTS

There were 40 fractures (13.3%) in 304 patients after OWHTO, comprising 21 type II fractures (7.0%) and 19 type III fractures (6.3%). A single-factor variance analysis showed that the tibial bone cutting distance to the medial tibial edge (P = 0.02) and osteoporosis (P = 0.01) were significantly different from the fracture. Receiver operating characteristic curves showed that the critical distances for types II and III fractures were 40.5 and 47.1 mm, respectively. Logistic regression analysis showed that the ORs [odds ratios] of types II and III fractures were 1.061 (95% CI [confidence interval] = 1.010 to 1.115) and 1.064 (95% CI = 1.011 to 1.119), respectively.

CONCLUSIONS

In patients undergoing OWHTO, the risk factors for type II and III fractures are osteoporosis and the distance from the tibial bone cutting point to the medial tibial edge. This distance should be minimized during OWHTO to avoid type II and III fractures.

The effect of frontal plane osteotomy angle on lateral cortex fracture in medial open wedge high tibial osteotomy procedure

BACKGROUND

Precise high tibial osteotomy is crucial, especially for middle-aged individuals with medial compartment arthritis, aiming to prevent complications like lateral cortex fractures. This study explores how frontal plane osteotomy inclination impacts lateral cortex fractures during medial open-wedge high tibial osteotomy.

METHODS

Using finite element analysis, tibia models underwent osteotomies at angles of 10°, 13°, 16°, 19°, and 22°, forming five models. Forces from 5 N to 75 N were applied incrementally, recording bone stresses (MPa) at the lateral hinge, angle changes (°) along the osteotomy line, and gap distances (mm).

RESULTS

Models with higher frontal inclination showed increased gap distances under identical forces. For instance, at 5 N force, the 10° inclination model displayed a correction angle of 0.28° and a 1.43 mm gap, while the 22° model had a correction angle of 0.35° and a 1.37 mm gap. Under 75 N force, the 10° model had a correction angle of 10.81° and a 14.02 mm gap, while the 22° model had a correction angle of 16.86° and a 19.31 mm gap.

CONCLUSION

The osteotomy starting point's distance from the joint doesn't significantly impact final stress on the lateral cortex when the same gap distance is achieved. However, in cases requiring a higher degree of correction, we can say that the surgeon can achieve the result with less resistance by keeping the osteotomy starting point more distal to the joint line.

Finite element analysis confirms the optimal apex position in medial opening wedge high tibial osteotomy to avoid lateral hinge fracture

Purpose

Lateral hinge fracture is a significant complication of medial opening wedge high tibial osteotomy. While fracture risk is closely associated with the osteotomy apex position, the optimum position remains variable within the literature. Our hypothesis is that stresses at the osteotomy apex predicted by finite element analysis can be used to identify an apex position which minimises intra and postoperative fracture risks.

Methods

A finite element model was studied to investigate the effect of varying the hinge position on fracture risk and severity for a given bone geometry; variables analysed included stress, strain and micromotion levels. Nine further knee models were studied to assess the variability between patients' bone properties and examine the effect of apex location on strains.

Results

Lateral hinge width and height significantly influence intra-operative stress, strain, and fracture risk, while hinge width predominately determines postoperative stability. Wider hinges improve postoperative stability, but increase the likelihood of intra-articular fractures. Aiming the apex at the fibular head height minimises strain. The osteotomy apex should be located such that the hinge width is equal to 13% of the medial-lateral width to minimise apex stress and fracture risk while preserving sufficient bone at the hinge for stability. The height of the apex from the tibial plateau should maintain a minimum value of 16% of the medial-lateral width to avoid intra-articular fracture, with the apex below the fibula head if necessary. The size of the tibia does not alter the optimal location, making our findings applicable across all tibia sizes.

Conclusions

Our study has investigated and verified a proposed optimal apex position, based upon fracture risk prediction and micromotion at the osteotomy apex. This is clinically useful due to the potential use of the apex point on preoperative 2D radiographs when planning surgery.

Level of Evidence

Not applicable.

Larger lateral hinges increase the probability of Takeuchi type II and III fractures in high tibial osteotomy

PURPOSE

Lateral hinge fractures are the main complications in the high tibial osteotomy to treat varus deformities. The aim of present study is to answer the question whether the lateral hinge length (H) has an effect on the type of fracture and required force during the opening in high tibia osteotomy. It was hypothesized in this comparative research that extending the hinge length increased opening force and probability of a type II and type III fractures.

METHODS

A monoplanar medial open wedge osteotomy with different intact hinge lengths varying from 9 to 32 mm was performed in 20 ostrich bones. A biomechanical experiment using unidirectional tensile testing apparatus was performed to open the wedge, and the required force was increased until a 10 mm opening was reached; then, the presence of fracture in the lateral cortex and its direction were evaluated. Lateral hinge fracture type based on direction was classified as suggested by Takeuchi et al.

RESULTS

Fracture that grows along the osteotomy line (type I) was observed in 4 samples with the mean hinge length (H) of 11 ± 1.54 mm. For seven bones with Takeuchi fracture type II, with downward crack propagation, the mean H was 16 ± 3.36 mm. For the mean H of 25 ± 6.53 mm, the crack propagated upward to the cutting path, displaying a Takeuchi type III fracture in seven samples. The statistical analysis showed that the fracture type significantly depends on the hinge length (P value < 0.05). Also, the mean opening force significantly increased with hinge lengthening (P value < 0.05). The peak forces at crack initiation were 41.8 ± 21.9, 115.2 ± 41.5, and 167 ± 135.3 N, respectively, for the fracture types I, II, and III samples.

CONCLUSION

The lateral cortical hinge length was significantly associated with hinge fracture type. The experimental tests indicated that the hinge lengthening increases the risk of type II and III fractures, as classified by Takeuchi.

Editorial Commentary: Risk of Lateral Hinge Fracture After Knee Medial Opening-Wedge High Tibial Osteotomy Can Be Reduced With Osteotomy at the Level of the Proximal Tibiofibular Joint and Gap Width of No Larger Than 11 mm

Medial opening-wedge high tibial osteotomies are commonly performed to treat varus deformity and medial compartment osteoarthritis of the knee in active younger individuals. A common complication of this procedure is the development of a lateral hinge fracture. This can occur both acutely and with a delayed presentation. There are many considerations to reduce this fracture, including biplanar versus monoplanar osteotomy, amount of correction/gap width, level of the osteotomy, and lateral cortical distance of the osteotomy. To best reduce the risk of a lateral hinge fracture, place the level of the osteotomy at the level of the proximal tibiofibular joint, and maintain a gap width of no larger than ∼11 mm.