Comparison of three plate system for lateral malleolar fixation

This retrospective study was based on data collected in our prospective database and approved by the Institutional Review Board of West China Hospital of Sichuan University. From 2000 to 2011, 214 patients were treated by internal fixation for a closed, displaced distal fibular fracture in our center. Once the patients met our inclusion criteria (1. unilateral fractures; 2. patients treated with any of the three implants studied in our study; 3. patients with the ability to ambulate without assistance prior injury; 4. Patients who didn’t have osteoarthritis before surgery; 5. patients who had a full one year follow-up data), they were matched by age, BMI and the classifications of the fractures. Based on the different implants used different implants, patients were assigned into three groups: (1) Group A: treated with one-third tubular (Synthes GmbH, Switzerland); (2) Group B: treated with LCP metaphyseal plate (Synthes GmbH, Switzerland); (3) Group C: treated with LCP distal fibula plate (Synthes GmbH, Switzerland) (Figure 2).

Finally 147 patients (49 patients in each group) were included in our study. Trimalleolar fractures were diagnosed in 39 patients, bimalleolar fractures were diagnosed in 88 patients and isolated lateral malleolus fracture was diagnosed in 20 patients. Based on the Weber (AO) classification [10], they were divided into three subgroups: Weber A group: a total of 24 patients (8 patients in each group); Weber B group: a total of 93 patients (31 patients in each group); Weber C group: a total of 30 patients (10 patients in each group).

All the surgeries were performed by the same surgical team (L.L, Z.H) in the same laminar air flow operating room. The team had performed more than 100 surgeries using these implants. Patients were given 1.5 g cefuroxime within 30 minutes prior to skin incision, and general anesthesia was administered in all cases. In Group A, the conventional lateral approach was used while in Group B and C the MIPO technique was used as described by Hess et al. [11]. Tourniquet was placed in all the patients at 100 mmHg above systolic blood pressure. The tourniquet was inflated before incision and deflated after the placement of the implants and then the hemostasis was made before closing the wound.

After the surgery, the patients were transferred first to the anesthesia recovery unit for a 2-h period and then to the in-patients unit. Once they were sent to the in-patients unit, cold pack was used on the surgical sites for 12 hours. The drain was removed after 24 hours before being removed. Celecoxib was administered orally with a regular dose of 200 mg bid for pain control regularly after the operation if there was no contraindication. Then it was administered as requested.

In Group A, the patients were mobilized without weight bearing for 6 weeks after the surgery before partial weight bearing was allowed. At the 2 months follow-up weight bearing was initiated after the radiographs being obtained. While in Group B and C, ambulation was started with toe-touch weight bearing of 10 to 15 kg once the soft tissue permitted. Full loading was not allowed until 2 months after the surgery. Patients were followed up in the clinic at 1 month, 2 months, 3 months, 6 months, 1 year after the surgery. Clinical assessment of the soft tissue and ankle function was assessed by a surgeon, while postoperative re-constructive protocols for the patients were done by a physical therapist.

Clinical outcomes were assessed by both the ankle range of motion (ROM) from the full extension to full flexion and the functional questionnaires including abbreviated Olerud & Molandar Score (OMS) and American Orthopaedic Foot & Ankle Society (AOFAS) clinical rating system [12, 13]. The ROM of each ankle was measured twice in the supine position with a standard (60-cm) goniometer at the time of discharge and every follow-up time points. Details of complications and all the revision surgeries were recorded during the inpatient period and every follow-up time point. Bone healing was defined as follows: (1) pain-free at the location of fracture; (2) three of the four cortices were bridged by visible callus on both the anterioposterior (AP) and lateral view.

Radiographs of the anterioposterior, lateral and mortise view of the involved ankle were obtained preoperatively, postoperatively and at every follow-up time points. Preoperative MRI was taken in order to assess the soft tissue injury, especially the ligament injury. Tscheme classification [14] was used to assess the soft tissue injury. Routine radiographic parameters, including talocrucral angle (TCA) and the medial clear space were measured. The method described by McLennan and Ungersma [15] was used to assess the adequacy of reduction. These measurements were performed by two independent observers. If the no consensus were reached, a senior radiologist was invited to determine the case.

Data management and statistical analysis were performed by SPSS version 18.0 (SPSS Inc, Chicago, IL USA). Shapiro-Wilk test was used to analyze data normality. If the Levene’s test for comparison of variances didn’t reject hypothesis on equality of variance between groups, mean values were compared using ANOVA with Bonferroni correction. Kruskall-Wallis test was applied to non-normally distributed data. The Chi-square test was used to compare the categorical data among the three groups. Analysis was performed with significance level α = .05 (two sided).

At the final 12-month follow-up, multiple comparison analysis of the OMS score showed that: (1) totally, patients in Group C have a significantly better OMS score than those in Group A (86.3 ± 6.2 vs 82.1 ± 6.9, p = 0.004), while no differences were detected between Group B and Group C (Figure 3a). (2) in the patients with Weber A fracture: significant differences were detected between group A and C (82.5 ± 6.5 versus 90.6 ± 4.2, p = 0.02) and also between Group B and C (82.5 ± 8.0 vs 90.6 ± 4.2, p = 0.02), while no statistical differences were found between Group A and B (p = 1.0) (Figure 3b). (3) in the patients with Weber B fracture: significant differences were detected between Group A and B (81.3 ± 6.5 vs 85.2 ± 7.8, p = 0.033) and also between Group A and C (81.3 ± 6.5 vs 85.3 ± 6.7, p = 0.027), while no statistical differences were found between Group B and C (p = 0.928) (Figure 3c). (4) in the patients with Weber C fracture: no statistical differences were detected among the three groups (84.5 ± 8.3 vs 85.0 ± 8.2 vs 86.0 ± 4.6, p = 0.895) (Figure 3d).Multiple comparison of the final follow-up AOFAS score showed: (1) totally, also only significant difference was detected between Group A and Group C (84.0 ± 6.2 vs 88.4 ± 6.9, p = 0.002) (Figure 4a). (2)in the patients with Weber A fracture: statistical differences were detected between Group A and C(84.4 ± 6.1 vs 92.6 ± 3.4, p = 0.029) and also between Group B and C (84.6 ± 10.0 vs 92.6 ± 3.4, p = 0.034), while no statistical differences were found between Group A and B (p = 0.944) (Figure 4b). (3) in the patients with Weber B fracture: significant differences were detected between group A and B(83.2 ± 5.7 vs 86.9 ± 7.5, p = 0.03) and also between Group A and C (83.2 ± 5.7 vs 87.3 ± 6.4, p = 0.017), while no statistical differences were found between Group B and C (p = 0.817) (Figure 4c). (3) in patients with Weber C fracture, also no significant differences were detected among the three groups (86.2 ± 7.9 versus 87.4 ± 8.1 versus 88.3 ± 4.5, p = 0.801) (Figure 4d).

Totally, no significant differences were detected in terms of ROM among the three groups (54.5 ± 9.8°vs 55.6 ± 8.7°vs 55.7 ± 8.6°, p = 0.760). Also significant differences were missing when we did the subgroup analysis (Table 3).

Only one patient associated with a Type A fracture in Group B was confirmed with a poor reduction accuracy by postoperative 3D-CT scan. No statistical significant was achieved among the three groups of any subgroups in terms of reduction accuracy (Table 3). The healing time was significantly less in patients of Group C than those in Group A (20.0 ± 3.8w vs 23.1 ± 3.6w, p < 0.0001) and Group B (20.0 ± 3.8w vs 23.0 ± 3.4w, p < 0.0001). While no significant difference was found between Group A and Group B (p = 0.867).

One patient with the Weber A fracture treated with one-third tubular plate was diagnosed superficial infection clinically during the inpatient period. He was treated with regular dressing change and intravenous antibiotics. The infection was controlled avoiding hardware removal. At the final follow-up, the patient had a ROM of 50°. One patient of Group B with Weber A fracture was found nonunion. No deep infection or loss of reduction was found in the 147 patients until the final follow-up. None developed superficial peroneal nerve injury.