The outcomes of surgical treatment for lateral Hoffa fracture nonunions

Plate-augmented fixation of comminuted Letenneur type II Hoffa fractures provides favorable stability compared to isolated posteroanterior screw fixation - a biomechanical study

INTRODUCTION

Current literature lacks recommendations regarding proper fixation of comminuted coronal plane fractures of the posterior femoral condyles (Hoffa fractures). Therefore, the aim of this study was to compare the biomechanical characteristics of different plate-augmented constructs to isolated posteroanterior screw fixation in comminuted lateral Hoffa fractures.

MATERIALS AND METHODS

Comminuted Letenneur type IIb lateral Hoffa fractures were simulated in 24 human cadaveric distal femora. The fractures were fixed with either isolated crossed posteroanterior screws or additionally with either a posterior plate, a lateral locking plate, or combined posterior and lateral locking plates. All specimens were biomechanically tested under progressively increasing cyclic loading until failure, while capturing the interfragmentary movements of the Hoffa and intercalary fragments via motion tracking.

RESULTS

Plate-augmented posteroanterior screw fixation of the Hoffa fragment exhibited higher cycles to failure, higher failure loads (p < 0.05) and less axial displacements (p < 0.05) compared to isolated posteroanterior screw fixation. Both additional lateral locking and double plate fixations of the intercalary fragment provided higher cycles to failure, higher failure loads (p < 0.05) and less axial displacement (p < 0.05) than isolated posteroanterior screw fixation, whereas additional posterior plate fixation did not significantly increase cycles to failure, failure loads and axial displacement (n.s.). Fracture gap twisting and opening did not differ significantly between the four constructs for the Hoffa fragment, while plate-augmented constructs provided less fracture opening of the intercalary fragment compared to isolated posteroanterior screw fixation (p < 0.01).

CONCLUSIONS

Plate-augmented posteroanterior screw fixation of comminuted Letenneur type IIb Hoffa fractures provided greater biomechanical stability than isolated posteroanterior screw fixation. While additional lateral or double plate fixation improves the stability of both the intercalary and Hoffa fragment, posterior plating stabilized only the Hoffa fragment.

Magnesium versus titanium headless compression screws for fixation of a Hoffa-type fracture - a biomechanical in-vitro study

BACKGROUND

Intraarticular (e.g., Hoffa-type) fractures are usually stabilized with titanium screws, which may necessitate later implant removal. The aim of this study was to compare the biomechanical strength and stability of magnesium and titanium screws.

METHODS

18 double-layer bone blocks were fixed with 18 one-layer bone blocks and divided into 2 groups based on the fixation method: magnesium screw fixation (Magnesium group, n = 9) and traditional titanium screw (Titanium group, n = 9). Compressive force was applied to the specimens orthogonally to the screw axis. First, axial stiffness was measured, and a cyclic loading test was performed, after 10, 100, 1000 and 10,000 cycles respectively, and the axial displacements were recorded. Finally, the specimens were loaded to failure.

RESULTS

There were significant differences between the groups with respect to axial stiffness and cyclic loading. The ultimate failure load was comparable. The average axial stiffness for the magnesium group was 326 ± 67 N/mm and for the titanium group 266 ± 72 N/mm (p = 0.031). The axial displacement relative to 100 N preload after 10,000 cycles in the magnesium group was 1.7319 ± 0.2261 mm and in the titanium group 2.6932 ± 0.5921 mm (p < 0.001). The average ultimate failure in the magnesium group was 920 ± 55 N and in the titanium group 944 ± 40 N (p = 0.293).

CONCLUSIONS

Based on the results magnesium screws show at least a comparable strength and stability as titanium screws in this setting. This study provides support from a biomechanical perspective for the use of magnesium screws in Hoffa fractures.

CLINICAL TRIAL NUMBER

Not applicable.

Busch-Hoffa fracture: A systematic review

BACKGROUND

Accomplish a thorough review on the existing biomechanical and clinical studies about coronal plane fractures of the distal femur.

METHODS

We performed an electronic search of PubMed/MEDLINE database from April to June, 2023. The terms for the database search included "Hoffa fractures," OR "Busch-Hoffa fractures" OR "coronal plane fractures of the distal femur."

RESULTS

The search identified 277 potentially eligible studies. After application of inclusion and exclusion criteria, 113 articles were analyzed in terms of the most important topics related to coronal plane fractures of the distal femur.

CONCLUSION

Lateral coronal plane fractures of the distal femur are more frequent than medial, present a more vertical fracture line, and usually concentrate on the weight bearing zone of the condyle. The Letenneur system is the most used classification method for this fracture pattern. Posterior-to-anterior fixation using isolated lag screws (for osteochondral fragments-Letenneur type 2) or associated with a posterior buttressing plate (when the fracture pattern is amenable for plate fixation-Letenneur types 1 and 3) is biomechanically more efficient than anterior-to-posterior fixation. Anterior-to-posterior fixation using lag screws complemented or not by a plate remains a widely used treatment option due to the surgeons' familiarity with the anterior approaches and lower risk of iatrogenic neurovascular injuries. There is no consensus in the literature regarding diameter and number of screws for fixation of coronal plane fractures of the distal femur.