Fully threaded headless compression screw versus partially threaded cancellous lag screw in medial malleolus fractures: clinical and radiological outcomes

Comparison of two versus three-screw fixation for biplanar chevron medial malleolar osteotomy

PURPOSE

This study was designed to compare the clinical outcomes and complications of using two versus three screws to fix the biplanar chevron medial malleolar osteotomy (MMO).

PATIENTS AND METHODS

A retrospective review was conducted on 43 patients (46 ankles) who underwent biplanar chevron MMO to treat talus osteochondral lesions. Of these, MMO was fixed with two parallel screws placed perpendicular to the osteotomy plane in 16 ankles, while in the remaining 30 ankles, MMO was secured with two parallel screws plus an additional third screw inserted parallel to the tibial plafond. Patients were divided into two groups based on the fixation method and clinical outcomes, union and malunion rates, and complications were compared.

RESULTS

Demographic and clinical characteristics such as age (p: 0.411), gender distribution (p: 0.119), affected side (p: 0.126), lesion grades (p: 0.056), and lesion sizes (p: 0.310), immobilization (p: 0.119) and weight-bearing periods (p: 0.252) were statistically similar across both groups. Initial malreduction were observed in five cases within the three-screw group and one case in the two-screw group (p: 0.307). However, neither group exhibited any progressive step-off or gap in the follow-up radiographs, and osteotomy union was achieved in all patients. Delayed union was observed in one patient from the three-screw group. Significant improvements in American Orthopedic Foot and Ankle Society scores were observed in both groups, with no functional discrepancies evident at the final follow-up (p: 0.488).

CONCLUSIONS

The study found no significant differences in union rates, complications, or clinical outcomes between two and three-screw fixation methods for medial malleolar osteotomies (MMO). Both methods allowed for effective MMO fixation without loss or displacement post-surgery, suggesting their safety and efficacy.

LEVEL OF EVIDENCE

Level III, retrospective comparison.

Is just one screw really enough? Single- versus double-screw in the medial malleolus in supination-external rotation ankle fractures: A comparative biomechanical study using partially threaded cancellous screws

OBJECTIVE

The aim of this study is to investigate stiffness and the maximum load to failure values of single- and double-screw fixation of oblique medial malleolus fractures using partially threaded cancellous screws. Our hypothesis is that single-screw fixation of medial malleolus fractures after SER injuries provides similar stiffness when compared with double-screw fixation.

DESIGN

Biomechanical study.

METHODS

Twelve composite polyurethane synthetic right distal tibiae were used in the experiment. Oblique fractures of the medial malleolus were created with a band saw using a custom-made osteotomy guide to standardize the cuts in all models. Bone models were randomly separated into two groups and fixed with one (n = 6) or two (n = 6) 4.0 mm partially threaded cancellous screws placed perpendicular to the fracture line. These were tested by applying an offset axial tension at 10 mm/minute up to maximum load displacement, defined as subsidence of the medial malleolus fragment. Maximum load to failure was determined for the groups at the point where the curve ceased to be linear and suffered an inflection. Force versus displacement curves were obtained and recorded. The student's t-test for independent samples was used to compare stiffness (N / mm) and maximum load (N) between experimental groups, with a p value of < 0.05.

RESULTS

There were no significant differences in stiffness (p = 0.290) and maximum load (p = 0.191) among the two fixation constructs. Mean stiffness was 62.26 (±SD 21.11) N/mm for double-screw fixation group and 48.24 (±SD 22.40) N/mm for single-screw fixation group. Mean maximum load was 387.83 (±SD 115.78) N for double-screw fixation group and 306.64 (±SD 81.97) N for single-screw fixation group.

CONCLUSION

Fixation with one 4.0 mm partially threaded cancellous screw was not shown to be biomechanically inferior to fixation with two 4.0 mm partially threaded cancellous screws in an oblique fracture of the medial malleolus, supporting previous clinical studies that have shown that one screw is sufficient for fractures of the medial malleolus.

Effect of buttress plate in Herscovici type D vertical medial malleolar fractures and peripheral fractures: a retrospective comparative cohort study

BACKGROUND

The purpose of current retrospective study was to review the surgical methods and to evaluate the clinical efficacy of supporting plate for the treatment of vertical medial malleolus fractures on the basis of stable fixation of ipsilateral fibula.

METHODS

This retrospective study included a total of 191 patients with vertical medial malleolus fractures. Patients enrolled were divided into simple vertical medial malleolus fractures and complex types of fractures. General demographic information and surgical information, including age, sex, surgical procedure and postoperative complications, were collected. The functional prognosis of patients was evaluated by American Orthopedic Foot and Ankle Society Ankle-Hindfoot Score (AOFAS) and Visual Analog Scale (VAS).

RESULT

Among patients with simple vertical fractures, the respective incidence of internal fixation failure in screw group, buttress plate group, and screw combined buttress plate fixation group (combined fixation group) was 10/61 (16.4%),1/54 (7.4%) and 1 (1.9%), and the difference was statistically significant (P = 0.024). The incidence of abnormal fracture growth and healing in screw group, buttress plate group and combined fixation group was, respectively, 13/61 (21.3%), 6/54 (12.5%) and 2 (3.85%), with statistically significant difference (P = 0.019). In the patients with complex types of fractures, after 2 years of postoperative follow-up, the AOFAS score and VAS score of the following subgroups had good results: 91.18 ± 6.05 and 2.18 ± 1.08 in patients with joint surface collapse, and 92.50 ± 4.80 and 2.50 ± 1.29 in patients with tibial fractures, with 100% excellent and good rate.

CONCLUSION

For simple and complex vertical medial malleolus fractures, buttress plate showed excellent fixation. Despite poor wound healing and extensive soft tissue dissection with this approach, buttress plate may provide a novel insight into medial malleolar fractures, especially for extremely unstable medial malleolar fractures.

Is there a Difference in Interfragmentary Compression Strength Between Fully or Partially Threaded Screws? Results of an Experimental Biomechanical Pilot Study

Objective  This study assessed differences between fully- and partially-threaded screws in the initial interfragmentary compression strength. Our hypothesis was that there would be an increased loss in initial compression strength with the partially-threaded screw. Methods  A 45-degree oblique fracture line was created in artificial bone samples. The first group (FULL, n  = 6) was fixed using a 3.5-mm fully-threaded lag screw, while the second group (PARTIAL, n  = 6) used a 3.5-mm partially-threaded lag screw. Torsional stiffness for both rotational directions were evaluated. The groups were compared based on biomechanical parameters: angle-moment-stiffness, time-moment-stiffness, maximal torsional moment (failure load), and calibrated compression force based on pressure sensor measurement. Results  After loss of one PARTIAL sample, no statistically significant differences in calibrated compression force measurement were observed between both groups: [median (interquartile range)] FULL: 112.6 (10.5) N versus PARTIAL: 106.9 (7.1) N, Mann-Whitney U-test: p  = 0.8). In addition, after exclusion of 3 samples for mechanical testing (FULL n  = 5, PARTIAL n  = 4), no statistically significant differences were observed between FULL and PARTIAL constructs in angle-moment-stiffness, time-moment-stiffness, nor maximum torsional moment (failure load). Conclusion  There is no apparent difference in the initial compression strength (compression force or construct stiffness or failure load) achieved using either fully- or partially-threaded screws in this biomechanical model in high-density artificial bone. Fully-threaded screws could, therefore, be more useful in diaphyseal fracture treatment. Further research on the impact in softer osteoporotic, or metaphyseal bone models, and to evaluate the clinical significance is required.