Abstract
Aims and background
Intra-articular distal tibia fractures can lead to post-traumatic osteoarthritis (PTOA). Joint distraction has shown promise in elective cases of osteoarthritis (OA) by temporarily offloading joint forces and potentially facilitating cartilage regeneration. However, its application in acute fractures remains unexplored. This pilot study aims to investigate the benefits of joint distraction in acute fractures.
Material and methods
A retrospective cohort study comprising consecutive patients with intra-articular distal tibia and pilon fractures, treated with a circular ring fixator (CRF) and ankle distraction as part of their fracture management, was undertaken at a single centre.
Prospective data collection included radiological assessments, patient-reported outcome measures (PROM), complications, necessity for additional procedures, and the Kellgren and Lawrence grade (KL) for OA.
Results
There were 137 patients included in the study, among them 30 in the distraction group and 107 in the non-distraction group. There were no significant differences in age, gender, distribution of open or closed fractures, diabetic status, and smoking status between the groups. Mean follow-up was 3.73 years.
There was no significant difference between the distraction and non-distraction groups in overall complications or need for further procedures. The mean radiological follow-up was 1.90 years, there was no significant difference in progression of KL between the groups (1.81 vs 2.0, p = 0.38). There were 32 patients who had radiological follow-up exceeding 2 years (average 3.52 years); here there was no significant difference between these groups (mean change 2.18 vs 2.4, p = 0.87).
Patient-reported outcome measures data was available for 44 patients (6 in the distraction group, 38 in the non-distraction group) with a mean follow-up of 1.71 years. There were no significant differences in EQ5D and C Olerud-H Molander scores between the two groups.
Conclusion
Ankle joint distraction in the management of acute ankle fractures did not influence outcomes for patients in short and medium term follow-up. Future work should investigate for long-term effects of this auxiliary technique when using circular external fixators, in particular on the development of PTOA.
How to cite this article
Faraj A, Hammett F, Lineham B, et al. Outcomes of Acute Ankle Distraction for Intra-articular Distal Tibial and Pilon Fractures. Strategies Trauma Limb Reconstr 2025;20(1):6–10.
Keywords: Ankle fractures, Circular external fixation, Circular frame, Complications, Distraction, Pilon fracture, Patient-reported outcome measures, Tibial pilon
Introduction
Intra-articular fractures of the distal tibia are a challenging orthopaedic problem and cause substantial burden to patients and the healthcare system.1 Due to the high energy nature of injury, there is often damage to soft tissues and associated injuries.2 After immediate management, definitive treatment can include casting or surgical approaches; examples are open reduction and internal fixation (ORIF) or external fixation with an ankle-spanning frame.3,4 Open wounds or poor soft tissue conditions can delay definitive surgery, subsequently making open reduction difficult. For such complex injuries, ankle-spanning ring fixators are often the treatment of choice and produce good outcomes in the short term with equivalent functional outcomes.5–7
Important sequelae of intra-articular distal tibial fractures is post-traumatic osteoarthritis (PTOA) of the ankle joint; this is reported to develop in an estimated 40% at 2 years, and 69% at 5 years.8–11 Post-traumatic osteoarthritis is a substantial functional burden on patients and may necessitate further intervention such as arthrodesis.12–14 Whilst arthrodesis alleviates pain, there are issues around loss of joint motion, adjacent joint arthritis and altered gait.15 An emerging approach for ankle osteoarthritis (OA) is joint distraction via external fixation which has yielded promising results.16–21 This joint-preserving technique has multiple proposed mechanisms of action including mechanical and biochemical changes in subchondral bone, changes in the molecular structures of the joint, and synovial fluid pressure oscillation.22
Cartilage damage occurs in an ankle fracture. As joint distraction can reduce inflammation and cartilage degeneration, it is hypothesised that acute joint distraction for ankle fractures managed in circular ring fixators (CRFs) can lead to lessened cartilage damage and improved outcome.23 Currently there is one case report describing the use of ankle distraction in the acute management of an ankle fracture with an external ring fixator, which concluded good ankle function at 1-year follow-up.24 Hence, the aim of this study was to investigate the outcome of acute ankle joint distraction for intra-articular distal tibial fractures and its effect on complications, need for further intervention, radiological appearances of OA, and patient related outcomes.
Material and Methods
Data for all patients in one centre undergoing circular frame fixation were recorded prospectively in a database. This included patient demographics, site of fracture, surgical technique, and complications. The database for the period 2014–2023 was queried for all patients with fractures that involved the ankle joint, including bi-malleolar, tri-malleolar, pilon, and distal tibial fractures with extension into the ankle joint.
All surgeries had been performed by one of three consultant orthopaedic surgeons. The interventions with regard to ankle distraction varied. One surgeon's practice was to distract any fractures involving the ankle. The other two rarely applied distraction, only doing so when there was severe comminution at the joint.
The following parameters were assessed for clinical outcomes. The ankle range of movement and patient reported outcome measures (PROMs) were collected between 1 and 2 years from the date of surgery. These included the EQ5D and Olerud-Molander ankle scores.25,26 In addition, the electronic patient records were reviewed retrospectively to evaluate if distraction was applied, summarise patient comorbidities, identify any complications or need for further interventions.
The primary outcome measure was the need for any further intervention, with the secondary outcome measures being the Kellgren and Lawrence grade for OA on the final radiograph and the PROM scores at a minimum of 1 year post-operatively. Initial presentation radiographs and final radiographs before discharge from follow-up were reviewed and scored from 1 to 4 on the Kellgren and Lawrence grade for OA.
Data collection and subsequent analysis were executed using Microsoft Excel software (Microsoft, Washington, USA). Demographic data between the distraction and non-distraction groups were compared with unpaired t-test for age, and Chi-square tests for all other parameters. For the primary outcome, Chi-square tests were used to compare outcome differences between the distraction and non-distraction groups.
The difference between scores on the Kellgren and Lawrence grade for OA from initial presentation radiographs and final radiographs were calculated. Patient-reported outcome measures score data demonstrated parametric distribution as indicated by Skew and Kurtosis assessments. Unpaired t-tests were performed to compare the distraction to the non-distraction group for each score.
Approval for the study was granted by the local governance committee (TRAUMA/CA/2023-24/18) February 2024.
Results
A total of 137 patients were identified for analysis from November 2014 to February 2023. Of these, 30 received ankle distraction and 107 did not. The median age at the time of surgery was 46.73 years in the distraction group and 47.92 years in the non-distraction group (p = 0.707). Demographic data is presented in Table 1. The groups had equal distribution of gender, diabetic status, smoking status, and the number of open fractures.
Table 1.
Demographics data of sample used for the study
| Characteristics | Distraction | Non-distraction | p-value |
|---|---|---|---|
| Total Sample | 30 | 107 | |
| Mean age ± SD | 46.73 ± 14.11 | 47.92 ± 15.55 | 0.707 |
| Gender | 0.513 | ||
| Male | 21 (70.00%) | 68 (63.55%) | |
| Female | 9 (30.00%) | 39 (36.45%) | |
| Diabetic status | 0.661 | ||
| Diabetes | 2 (6.67%) | 5 (4.67%) | |
| No diabetes | 28 (93.33%) | 102 (95.33%) | |
| Smoking status | 0.113 | ||
| Smoker | 10 (33.33%) | 21 (19.63%) | |
| Non-smoker | 20 (66.67%) | 86 (80.37%) | |
| Open/closed fracture | 0.318 | ||
| Open | 8 (26.67%) | 39 (36.45%) | |
| Closed | 22 (73.33%) | 68 (63.55%) |
SD, standard deviation
The mean follow-up for complications and further interventions was 4.18 years for the distraction group and 3.57 years for the non-distraction group (p = 0.178). Complications are listed in Table 2; there are no statistically significant differences in overall rate of complications (p = 0.233): pin site infections (p = 0.224), deep infections/osteomyelitis (p = 0.391), delayed union (p = 0.917), non-union (p = 0.751), and broken wires (p = 0.089). Of the 30 patients in the distraction group, 11 underwent further procedures (36.67%); compared to 27 out of 107 patients in the non-distraction group (25.23%). This was not a statistically significant difference (p = 0.230). Further procedures are displayed in Table 3. As the groups were shown to be equivalent statistically in age, demographics and key co-morbidities, a subgroup analysis was not done.
Table 2.
Complications developed in sample group (distraction and non-distraction)
| Complication | Distraction | Non-distraction | p-value | ||
|---|---|---|---|---|---|
| n | (%) | n | (%) | ||
| Total complications | 16 | (53.33%) | 44 | (41.12%) | 0.233 |
| Pin site infection | 8 | (26.67%) | 18 | (16.82%) | 0.224 |
| Deep infection/osteomyelitits | 3 | (10.00%) | 6 | (5.60%) | 0.391 |
| Delayed union | 1 | (3.33%) | 4 | (3.74%) | 0.917 |
| Non-union | 1 | (3.33%) | 5 | (4.67%) | 0.751 |
| Broken wire | 3 | (10.00%) | 3 | (2.80%) | 0.089 |
| Further fracture | – | – | 1 | (0.93%) | – |
| Prominent screw | – | – | 1 | (0.93%) | – |
| Equinus deformity | – | – | 1 | (0.93%) | – |
| Knee stiffness | – | – | 1 | (0.93%) | – |
| Scar contracture | – | – | 1 | (0.93%) | – |
| Osteoarthritis | – | – | 2 | (1.87%) | – |
| Death | – | – | 1 | (0.93%) | – |
Table 3.
Further procedures for each sample group (distraction and non-distraction)
| Further procedures | Distraction n (%) | Non-distractionn (%) | p-value |
|---|---|---|---|
| Total number of patients receiving further procedure | 11 (36.67%) | 27 (25.23%) | 0.230 |
| Total further procedures | 14 | 42 | – |
| Procedures due to pain or failure of metalwork | |||
| Revision frame | 0 | 2 | – |
| Removal of metalwork (non-infected) | 5 | 7 | – |
| Joint steroid injection | 1 | 2 | – |
| Scar contracture release | 0 | 1 | – |
| Procedures due to infection | |||
| Removal of metalwork (infected) | 0 | 6 | – |
| Excision osteomyelitis and stimulan/cerament insertion | 0 | 2 | – |
| Debridement | 1 | 4 | – |
| Joint washout | 1 | 0 | – |
| Procedures for non-union/delayed union | |||
| Revision frame | 0 | 2 | – |
| Bone graft | 1 | 5 | – |
| Over-drilling site | 2 | 3 | – |
| BMAC | 3 | 5 | – |
| Further metalwork (nail, plate) | 0 | 3 | – |
BMAC, bone marrow aspirate concentrate
There were 118 patients who had Kellgren and Lawrence scores. One patient's pre-operative radiograph could not be assessed accurately due to destruction of the ankle joint in the injury, and 17 patients lacked follow-up radiographs. In total, the radiographs of 26 patients were assessed in the distraction group, and 92 in the non-distraction group. The mean pre-operative score was 0.29 for the distraction group and 0.50 for the non-distraction group (p = 0.183). The mean time difference between pre-operative radiograph and final post-operative radiograph was 2.39 years in the distraction group and 1.77 years in the non-distraction group (p = 0.039). There was an average increase of 2.00 points on the Kellgren and Lawrence grade for the distraction group post-operatively and 1.83 points for the non-distraction group. This is illustrated in Figure 1. This was not a statistically significant difference (p = 0.430). Since OA often takes 2 years to develop post injury, further analysis was done on patients who had post-operative radiographs over 2 years following injury; there were 11 patients in the distraction group and 21 in the non-distraction group. Both groups showed a statistically similar mean increase in score (2.18 vs 2.24, p = 0.870).
Fig 1.
Kellgren and Lawrence grade for OA for each group, pre-op and post-op
Patient-reported outcome measures scores were available for 44 patients. The mean duration of follow-up was 24 months in the distraction group and 19.9 months in the non-distraction group. Table 4 demonstrates the number of patients in whom each measurement was collected and the mean scores for the distraction and non-distraction groups. Notably, none of the PROM scores or measurements exhibited statistically significant differences between the two groups.
Table 4.
Follow-up PROM scores for each group (distraction and non-distraction)
| PROM | n total | Distraction group | Non-distraction group | ||
|---|---|---|---|---|---|
| n | Mean | n | Mean | ||
| EQ5D mobility | 44 | 6 | 1.50 | 38 | 1.42 |
| EQ5D self-care | 44 | 6 | 1.00 | 38 | 1.05 |
| EQ5D usual activities | 44 | 6 | 1.50 | 38 | 1.37 |
| EQ5D pain | 44 | 6 | 1.88 | 38 | 1.71 |
| EQ5D anxiety | 44 | 6 | 1.33 | 38 | 1.34 |
| Olerud-Molander ankle score | 44 | 6 | 47.50 | 38 | 62.26 |
Discussion
This retrospective cohort study of patients with ankle fractures managed with circular frame fixator investigated whether the application of ankle joint distraction affected outcomes. With regard to the primary study outcome, there was no statistically significant difference in the subsequent need for further procedures whether distraction was applied or not. The secondary study outcomes investigated Kellgren and Lawrence grading of radiographs for OA and PROMs at 1–2 years follow-up and, again, found no statistically significant differences in measurement scores whether distraction was applied or not.
Ankle-spanning frames are often necessary for more severe injuries such as pilon fractures, or where soft tissue damage makes ORIF less suitable. Applying ankle distraction through frames offloads the cartilage and may encourage cartilage regeneration, as seen in its use in OA.16–21 Therefore, ankle distraction, in cases where ankle-spanning frames are necessary, may be a logical technique to use.
There are currently no published series looking into this, apart from one case report.24 Current work in the literature reports on joint distraction in the management of established OA. Investigating the effect of ankle joint distraction in acute fractures on the development of PTOA is an important area for future research, and this study can be interpreted as a first step in this work. In this study, there were similar results in the ankle distraction group to the non-distraction group for acute fractures.
The distraction group were followed up radiographically for a longer period, but the two groups had similar periods of clinical follow-up. This could potentially have had an impact on the rate of complication pick up or the need for further procedures.
A key limitation of this study is that patients were not randomised into distraction and non-distraction groups, with patient management determined by the individual surgeon choice. This introduces a significant source of bias, as each surgeon had their own preferred approach, leading to potential variability in patient management and follow-up. Additionally, the study's retrospective design resulted in incomplete data, particularly with the PROMs. Due to the COVID-19 pandemic and necessary cancellations of non-urgent face-to-face consultations, many patients missed follow-up appointments which would have recorded PROMs.
The centre where this study was conducted acts as a major trauma centre for the wider region, and so accepts referrals from peripheral hospitals for specialist care. Following frame removal, patients are often repatriated back to their respective hospitals, and so this creates a potential gap in the data collection. Therefore, access to any subsequent complications or need for further procedures in these peripheral hospitals were not recorded in the centre's database. A more complete database, or a larger sample size, may have altered the findings.
A further limitation is the magnitude of distraction. It has been suggested in the literature that at least 5.69 mm of distraction is necessary to offload the ankle cartilage, but in this study, we did not routinely measure the joint distraction, and the surgeons who used distraction with their management did not formalise the technique.27
Conclusion
A retrospective cohort study was performed investigating for potential benefits in ankle distraction for ankle fractures. Ankle joint distraction in the management of acute ankle fractures did not influence outcomes for patients in short and medium term follow-up. Future work should investigate for long-term effects of this auxiliary technique when using circular external fixators, in particular on the development of PTOA.
Orcid
Ara Faraj https://orcid.org/0000-0001-6827-3978
Footnotes
Source of support: Nil
Conflict of interest: None
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