A comparison of bone union between locking plate with and without lag screw in distal fibula fractures: A retrospective study

Abstract

Ankle fractures are among one of the most common lower limb trauma. Lag screw for interfragmentary compression with neutralization plate has been one of the most classical and commonly adopted operative modalities in fixing distal fibula fractures, though recent biomechanical studies suggest lag screws may not be essential for stability. This retrospective cohort study compared bone union rates and healing times between locking plates used with (n = 7) and without (n = 70) lag screws in 77 patients with distal fibula fractures. Radiographic outcomes, including time to union, reduction of quality, and complications, were analyzed. Results demonstrated no significant difference in mean healing time (12.7 weeks with lag screws vs. 13.3 weeks without, P = .42) or union rates (100% union in both groups). Articular incongruity was rare (1.4% in the plate-only group vs. 0% with lag screws), and no hardware failures or infections occurred in either cohort. Despite the lag screw group being older (mean age 58.7 vs. 50.5 years), outcomes remained comparable, suggesting that locking plates alone may provide sufficient stability for union in distal fibular fractures. These findings support the growing evidence that routine lag screw augmentation may not be necessary for straightforward distal fibula fractures when using modern locking plate constructs.

Introduction

Ankle fractures, particularly those involving the distal fibula, are among the most common lower limb injuries. The classical approach involves interfragmentary lag screw fixation with a neutralization plate. However, locking plates have gained popularity due to their perceived biomechanical advantages. Recent studies suggest that lag screws may not be essential for stable fixation. Park et al. found no significant biomechanical advantage when lag screws were used with locking plates in supination-external rotation (SER) fractures. ¹ This study aims to compare bone union rates and healing times between locking plates used with and without lag screws in distal fibula fractures in a local population.

Methods

Study design and patient selection

This retrospective cohort study analyzed patients who underwent surgical fixation for distal fibula fractures between April 2019 and May 2022 at a single institution. The initial patient pool (n = 142) was identified through implant procurement records of fibular locking plates. After applying strict exclusion criteria—including open fractures, concomitant tibial shaft fractures, and inadequate follow-up (<3 months)—77 patients remained for final analysis. These were stratified into two treatment groups: those receiving locking plate fixation with interfragmentary lag screws (n = 7) and those treated with locking plates alone (n = 70).

Preoperative assessment included standard ankle radiographs (AP, lateral, and mortise views) with fracture classification according to the Weber system. Surgical procedures were performed by orthopedic trauma surgeons using a standardized lateral approach. In the lag screw group, fracture reduction was achieved using pointed reduction forceps followed by placement of at least one 3.5-mm cortical lag screw perpendicular to the fracture line prior to the application of a precontoured distal fibular locking plate. The plate-only group utilized indirect reduction techniques with reduction clamp and K-wire temporary fixation and locking plate application without interfragmentary compression. All cases employed intraoperative fluoroscopy to verify anatomical reduction and hardware placement.

Postoperative protocol consisted of non-weight bearing for a minimum period of 6 weeks. Primary outcome measures included: (1) time to radiographic union (disappearance of fracture line and continuity of cortex), (2) quality of reduction (poor reduction is defined as 2 mm or more joint incongruitiy), and (3) complication rates. Secondary analysis examined demographic variables (age, sex) and fracture characteristics (Weber classification, mechanism of injury).

Statistical analysis

The data were analyzed using standard statistical tests to compare outcomes between the two treatment groups. For continuous variables like age and healing time, independent t-tests were performed, revealing no significant difference in mean healing times between groups (12.7 vs. 13.3 weeks, P = .42). Categorical variables including sex distribution, injury mechanism, and fracture classification were compared using chi-square tests. The proportion of female patients (57.1% vs. 62.8%, P = .72) and Weber B fractures (100% vs. 82.8%, P = .18) showed no statistically significant differences between groups. Fisher's exact test was used for articular incongruity rates due to small expected frequencies (0% vs. 1.4%, P = .99). All statistical tests were two-tailed with significance set at P < .05. The lack of significant P-values across all comparisons suggests comparable outcomes between locking plates with and without lag screws, though the small sample size in the lag screw group (n = 7) limits the power of these comparisons.

Results

This study analyzed 77 patients (48 females, 29 males) with a mean age of 52.3 years who underwent surgical fixation for distal fibula fractures. The cohort was divided into two treatment groups: 7 patients received lag screw augmentation with locking plates, while 70 patients were treated with locking plates alone.

Demographic analysis revealed notable differences between groups. The lag screw cohort was older (mean age 58.7 years vs. 50.5 years) with a slightly lower proportion of female patients (57.1% vs. 62.8%). Injury mechanisms showed similar patterns, with falls/sprains accounting for 42.8% of lag screw cases versus 35.7% in the plate-only group, sports-related injuries comprising 42.8% versus 52.8%, and other mechanisms (including road traffic accidents) representing 14.2% versus 11.4%. Fracture classification demonstrated that all lag screw cases were Weber B fractures, compared to 82.8% Weber B fractures in the plate-only group.

Radiographic outcomes were comparable between groups. Articular incongruity was observed in only one case (1.4%) from the plate-only group. Both techniques demonstrated excellent healing potential, with all fractures achieving primary union. The mean healing time was marginally shorter in the lag screw group (12.7 ± 2.3 weeks) compared to the plate-only group (13.3 ± 5.4 weeks), though this difference was not statistically significant (P > .05). The greater variability in healing times observed in the plate-only group (SD 5.4 weeks vs. 2.3 weeks) may reflect the larger sample size and broader inclusion of fracture patterns in this cohort.

Postoperative complications were minimal, with no reported cases of hardware failure, wound complications, or infections in either group. The absence of significant differences in union rates, healing times, or complication profiles between the two fixation methods suggests comparable efficacy in achieving fracture stabilization and healing.

These findings suggest that while lag screw augmentation may offer slight advantages in healing consistency, locking plate fixation alone remains an effective treatment option for distal fibula fractures, particularly in less complex fracture patterns. The comparable union rates and healing times between groups support the clinical equivalence of both techniques in achieving fracture stabilization.

Discussion

This study provides clinically relevant insights into the ongoing debate regarding optimal fixation techniques for distal fibula fractures. Our findings demonstrate comparable radiographic outcomes between locking plate fixation with and without lag screw augmentation, supporting the growing body of evidence that interfragmentary compression may not be essential when using modern locking plate constructs. ¹ The marginal difference in mean healing time (12.7 vs. 13.3 weeks) was neither statistically nor clinically significant, suggesting that the theoretical biomechanical advantage of lag screws may not translate into meaningful clinical benefits in routine Weber B fractures. These results align with recent biomechanical studies from Kim et al. and Nguyentat et al. showing that locking plates alone provide sufficient stability for fracture healing, particularly in non-comminuted fracture patterns.^2,3

The slightly better articular reduction observed in the lag screw group (0% vs. 1.4% incongruity) warrants careful consideration. While this difference did not reach statistical significance in our study, it may reflect the enhanced compression capability of lag screws in achieving anatomical reduction. However, the clinical relevance of this minor radiographic difference remains uncertain, particularly given that all fractures in both groups ultimately achieved union.

The age disparity between groups (mean 58.7 vs. 50.5 years) raises important questions about potential confounding factors. Older patients typically have reduced healing capacity and poorer bone quality, which might theoretically favor lag screw augmentation. That we observed comparable outcomes despite this age difference could suggest that locking plates alone may be particularly suitable for younger patients with good bone stock, while lag screws might still have value in osteoporotic bone but this required further investigation.

From a practical standpoint, our findings suggest that surgeons may reasonably omit lag screws in straightforward distal fibula fractures when using locking plates, potentially reducing operative time and minimizing complications associated with additional hardware. However, this approach should be balanced against specific patient and fracture characteristics, particularly in cases with significant comminution or poor bone quality where interfragmentary compression may still offer advantages as suggested by McKenna et al. ⁴

Future research directions would be beneficial from prospective randomized trials with standardized surgical protocols, larger sample sizes, and comprehensive assessment of both radiographic and functional outcomes. Particular attention should be paid to comparing these techniques in specific patient subgroups, such as elderly patients or those with osteoporosis, where the biomechanical advantages of lag screws might be most relevant. Longer-term follow-up studies would also help determine whether the small differences in initial reduction quality observed in our study translate into meaningful differences in functional outcomes or developments of post-traumatic arthritis.

Study limitations

This study has several important limitations that should be considered when interpreting the results. First, the significant imbalance in group sizes (7 patients in the lag screw group vs. 70 in the plate-only group) substantially limits the statistical power of our comparative analyses and increases the risk of type II errors. Second, the retrospective design introduces potential selection biases, as the decision to use lag screws may have been influenced by unmeasured factors such as fracture complexity or surgeon preference. The age disparity between groups (mean 58.7 vs. 50.5 years) suggests possible confounding by age-related healing capacity that was not accounted for in our analysis. Additionally, the relatively short follow-up period focused solely on radiographic union without assessment of functional outcomes or longer-term complications such as post-traumatic arthritis or hardware-related issues, which have been highlighted as significant considerations in Schepers’ study. ⁵ The predominance of Weber B fractures in our cohort (100% of lag screw cases and 82.8% of plate-only cases) limits the generalizability of our findings to more complex fracture patterns. Furthermore, the single-center nature of the study and potential variations in surgical technique among different surgeons may affect the external validity of our results. Future prospective studies with balanced group sizes, longer follow-up periods, and standardized outcome measures including both radiographic and functional assessments would provide more robust evidence regarding the optimal fixation strategy for distal fibula fractures.^6,7,8

Conclusion

This study demonstrates that both locking plate fixation with lag screws and locking plate fixation alone achieve reliable bone union in distal fibula fractures, with comparable radiographic healing times and minimal complications. While the lag screw group showed marginally faster mean healing time and slightly better articular reduction, these differences were not statistically significant. This suggests that lag screw augmentation may not be essential for successful fracture healing when using modern locking plate constructs, particularly in Weber B fracture patterns. Given the comparable outcomes, surgeons may consider omitting lag screws in straightforward fractures to reduce potential complications related to additional hardware and may also potentially reduce operative time. However, careful preoperative assessment of fracture pattern, bone quality, and soft tissue status remains crucial in surgical decision-making.