Effects of Fibular Plate Fixation on Ankle Stability in a Weber B Fracture Model With Partial Deltoid Ligament Sectioning.

BACKGROUND: Weber B fractures with concomitant deltoid ligament injury have traditionally been operated with open reduction and internal fixation of the fibular fracture. More recently, clinical studies have suggested that some fractures have concomitant partial deltoid ligament injury with the deep posterior tibiotalar ligament intact (SER4a), allowing for nonoperative treatment in this subgroup. This study explores whether plate fixation of the fibula improves ankle stability in an SER4a injury model. And if so, does it restore native ankle stability? METHODS: Fifteen cadaver ankle specimens were tested in 3 states using an industrial robot: intact joint, SER4a models without plate fixation of the fibula, and SER4a models with plate fixation of the fibula. The robot measured ankle stability in lateral translation, valgus, and internal and external rotation in 3 talocrural joint positions: 10 degrees dorsiflexion, neutral, and 20 degrees plantar flexion. Furthermore, fluoroscopic mortise view radiographs were taken to measure isolated talar shift and talar tilt. RESULTS: The talar shift and tilt tests showed no differences between the SER4a injury model with and without fibular plate fixation at neutral ankle position with a mean difference of -0.16 mm (95% CI -0.33 to 0.01 mm, P = .071) for talar shift and -0.15 degrees (95% CI -0.01 to 0.30 degrees, P = .068) for talar tilt. However, plate fixation increased external rotation stability, with mean improvements ranging from -7.43 to -9.52 degrees (P < .001 for all comparisons), but did not restore intact ankle stability. For internal rotation, plate fixation resulted in minor differences. CONCLUSION: The results of this suggest that plate fixation of the fibular fracture primarily improves external rotation stability but does not substantially improve lateral translation, valgus, or internal rotation stability in SER4a injury models. In this robotic cadaver model, fibular plate fixation did not fully restore intact ankle stability after simulated SER4a injury. CLINICAL RELEVANCE: This study offers insights into the effects of fibular plate fixation on Weber B/SER4a injury models and may assist informed decisions when selecting treatments for these types of fractures.

Functional orthosis versus cast immobilization for weightbearing stable Weber B ankle fractures with concomitant unstable gravity stress tests.

Aims: Treatment of Weber B ankle fractures that are stable on weightbearing radiographs but unstable on concomitant stress tests (classified SER4a) is controversial. Recent studies indicate that these fractures should be treated nonoperatively, but no studies have compared alternative nonoperative options. This study aims to evaluate patient-reported outcomes and the safety of fracture treatment using functional orthosis versus cast immobilization. Methods: A total of 110 patients with Weber B/SER4a ankle fractures will be randomized (1:1 ratio) to receive six weeks of functional orthosis treatment or cast immobilization with a two-year follow-up. The primary outcome is patient-reported ankle function and symptoms measured by the Manchester-Oxford Foot and Ankle Questionnaire (MOxFQ); secondary outcomes include Olerud-Molander Ankle Score, radiological evaluation of ankle congruence in weightbearing and gravity stress tests, and rates of treatment-related adverse events. The Regional Committee for Medical and Health Research (approval number 277693) has granted ethical approval, and the study is funded by South-Eastern Norway Regional Health Authority (grant number 2023014). Discussion: Randomized controlled trials are needed to evaluate alternative nonoperative treatment options for Weber B/SER4a ankle fractures, as current clinical guidelines are based on biomechanical reasoning. The findings will be shared through publication in peer-reviewed journals and presentations at conferences.

Effects of Progressive Deltoid Ligament Sectioning on Weber B Ankle Fracture Stability.

BACKGROUND: Conventionally, transsyndesmotic fibula fractures with concomitant signs of deltoid ligament injury have been considered unstable and thus treated operatively. Recent studies have indicated that partial deltoid ligament rupture is common and may allow for nonoperative treatment of stress-unstable ankles if normal tibiotalar alignment is obtained in the weightbearing position. Biomechanical support for this principle is scarce. The purpose of this study was to evaluate the biomechanical effects of gradually increasing deltoid ligament injury in transsyndesmotic fibula fractures. METHODS: Fifteen cadaveric ankle specimens were tested using an industrial robot. All specimens were tested in 4 states: native, SER2, SER4a, and SER4b models. Ankle stability was measured in lateral translation, valgus, and internal and external rotation stress in 3 talocrural joint positions: 20 degrees plantarflexion, neutral, and 10 degrees dorsiflexion. Talar shift and talar valgus tilt in the talocrural joint was measured using fluoroscopy. RESULTS: In most tests, SER2 and SER4a models resulted in a small instability increase compared to native joints and thus were deemed stable according to our predefined margins. However, SER4a models were unstable when tested in the plantarflexed position and for external rotation in all positions. In contrast, SER4b models had large-magnitude instability in all directions and all tested positions and were thus deemed unstable. CONCLUSION: This study demonstrated substantial increases in instability between the SER4a and SER4b states. This controlled cadaveric simulation suggests a significant ankle-stabilizing role of the deep posterior deltoid after oblique transsyndesmotic fibular fracture and transection of the superficial and anterior deep deltoid ligaments. CLINICAL RELEVANCE: The study provides new insights into how the heterogenicity of deltoid ligament injuries can affect the natural stability of the ankle after Weber B fractures. These findings may be useful in developing more targeted and better treatment strategies.

Concomitant Unstable and Stable Gravity Stress Tests on Weight-Bearing Stable Weber B Ankle Fractures Treated Nonoperatively: A 2-Year Outcome Study.

BACKGROUND: Replacing gravity stress tests with weight-bearing radiographs to evaluate the stability of Weber B (also called Lauge-Hansen supination-external rotation [SER]) ankle fractures results in a lower surgery rate, thus avoiding associated risks and complications. Still, nonoperative treatment of weight-bearing stable fractures is controversial because of the scarcity of strong evidence. We investigated the influence of a concomitant unstable gravity stress test compared with a stable gravity stress test on outcomes after nonoperative treatment of weight-bearing stable fractures. METHODS: We performed a prospective, noninferiority study on 149 patients with Weber B ankle fractures and stable weight-bearing radiographs. Gravity stress radiographs classified fractures as stable (SER2 [n = 88]) or partially unstable (SER4a [n = 61]). All were treated with a functional orthosis and weight-bearing was allowed; patients were followed for 2 years. The primary outcome was the Manchester-Oxford Foot and Ankle Questionnaire (MOXFQ), with a range from 0 to 100, in which lower scores indicate fewer symptoms. A noninferiority margin was prospectively defined as 7.5 points. The secondary outcomes included the Olerud-Molander Ankle Score, assessment of ankle congruence, and treatment-related adverse events. RESULTS: The primary outcome data were available for 144 (96.6%) of 149 participants at 2 years. The between-group difference in the MOXFQ score was 1.0 point (95% confidence interval, -1.4 to 3.4 points; p = 0.397) in favor of the SER2 group, consistent with noninferiority. We found no appreciable between-group differences for any other outcome. CONCLUSIONS: In Weber B/SER ankle fractures that are stable on weight-bearing radiographs, are treated with removable orthoses, and are allowed to bear weight, a concomitant unstable gravity stress test (SER4a) was not associated with worse patient-reported or radiographic outcomes compared with a stable gravity stress test (SER2) at the 2-year follow-up. Thus, the identification of stress instability seems redundant, which questions the applicability of stress instability for surgical decision-making. LEVEL OF EVIDENCE: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Higher complication rate after nail compared with plate fixation of ankle fractures in patients aged 60 years or older: a prospective, randomized controlled trial.

AIMS: The aim of this study was to compare the functional and radiological outcomes and the complication rate after nail and plate fixation of unstable fractures of the ankle in elderly patients. METHODS: In this multicentre study, 120 patients aged ≥ 60 years with an acute unstable AO/OTA type 44-B fracture of the ankle were randomized to fixation with either a nail or a plate and followed for 24 months after surgery. The primary outcome measure was the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score. Secondary outcome measures were the Manchester-Oxford Foot Questionnaire, the Olerud and Molander Ankle score, the EuroQol five-dimension questionnaire, a visual analogue score for pain, complications, the quality of reduction of the fracture, nonunion, and the development of osteoarthritis. RESULTS: At 24 months, the median AOFAS score was equivalent in the two groups (nail 90 (interquartile range (IQR) 82 to 100), plate 95 (IQR 87 to 100), p = 0.478). There were statistically more complications and secondary operations after nail than plate fixation (p = 0.024 and p = 0.028, respectively). There were no other significant differences in the outcomes between the two groups. CONCLUSION: The functional outcome after nail and plate fixation was equivalent; however, the complication rate and number of secondary operations was significantly higher after nail fixation. These results suggest that plate fixation should usually be the treatment of choice for unstable ankle fractures in the elderly.Cite this article: Bone Joint J 2023;105-B(1):72-81.

The Anatomy and Function of the Individual Bands of the Deltoid Ligament-and Implications for Stability Assessment of SER Ankle Fractures.

Background: Deltoid ligament injury occurs often with supination-external rotation (SER) ankle trauma. SER fibula fractures with concomitant deltoid ligament injury are considered unstable-requiring operative fixation. Recent studies have questioned this general practice with emphasis on better defining the medial side ankle ligamentous injury. The function of the individual bands of the deltoid ligament, and the interplay between them, are not fully understood. We undertook this study to develop a better understanding of these complex ligamentous structures and ultimately aid assessment and treatment choice of SER ankle fractures with concomitant deltoid ligament injuries. Methods: Ten fresh-frozen cadaveric foot and ankle specimens were studied. We identified the various ligament bands and did a functional analysis by assessment of ligament length and tension at predefined angles of ankle dorsi-plantarflexion combined with valgus/varus and rotation. The results were determined by manual evaluation with calipers and goniometers, manual stress, and direct visualization. Results: We recorded primarily 5 different bands of the deltoid ligament: the tibionavicular (TNL; 10/10) tibiospring (TSL; 9/10), tibiocalcaneal (TCL; 10/10), deep anterior tibiotalar (dATTL; 9/10), and deep posterior tibiotalar (dPTTL; 10/10) ligaments. The tibiospring ligament was tense in plantarflexion, while the tibiocalcaneal and deep posterior tibiotalar ligaments were tense in dorsiflexion. The superficial layer ligaments and the deep anterior tibiotalar ligament length and tension were largely affected by changes in varus/valgus and rotation. The deep posterior tibiotalar ligament length and tension was altered predominantly by changes in dorsi-plantarflexion; varus/valgus positioning had a minor effect on this band. Conclusions: We confirmed the finding of previous studies that dorsi-plantarflexion affects the tensile engagement of the separate ligament bands differently. Likewise, combined movements with varus/valgus and rotation seem to affect the separate ligament bands differently. Our results suggest that the TNL, TSL, and dATTL are at risk of injury, whereas the TCL and particularly the dPTTL are protected in the event of an SER-type ankle fracture mechanism of injury. Level of Evidence: Level V, cadaveric study.

Weightbearing Stable Bimalleolar Ankle Fractures-Bony Equivalents to the Ligamentous Weber B/SER4a Fracture Type? A Prospective Case Series.

BACKGROUND: In a recent study, we documented that partially unstable Weber B/SER4a fracture types reach union with preserved normal ankle congruence after treatment with a functional orthosis and weightbearing allowed. In the present article, we present a case series of weightbearing stable bimalleolar fractures treated nonoperatively that extends our previously published research. METHODS: We included 5 patients with primarily nondisplaced bimalleolar ankle fractures that were stable on weightbearing radiographs. Participants were treated with a walking boot or cast with weightbearing allowed. We also provide a qualitative anatomical analysis of fracture morphology on computed tomographic scans. RESULTS: Median medial clear space (MCS) of fractured ankles after union were 2.4 mm (range, 1.5-3.1). Qualitative descriptions of fracture morphology showed that all fractures were oblique starting at the intercollicular groove of the medial malleolus and extended anteriorly and proximally. CONCLUSION: MCS measurements after fracture union of nonoperatively treated weightbearing stable bimalleolar fractures seemed consistent with normative data of ankle congruence in our previous study. We consistently recorded oblique fracture patterns involving the anterior colliculus, leaving the origin of posterior deep deltoid ligament intact. We present our material as an argument for the existence of a bony (bimalleolar) equivalent to the ligamentous SER4a fracture. LEVEL OF EVIDENCE: Level IV, prospective case series.

Weightbearing Radiographs Reliably Predict Normal Ankle Congruence in Weber B/SER2 and 4a Fractures: A Prospective Case-Control Study.

BACKGROUND: In Weber B/SER2-4 ankle fractures, assessment with weightbearing radiographs to ascertain stability of the ankle mortise has been advised. However, no previous studies report whether this method leads to preservation of normal ankle congruence. The purpose is to evaluate equivalence of ankle congruence of injured ankles after fracture union, vs the uninjured side, for stable SER2 and partially unstable SER4a fracture types. METHODS: We conducted a prospective case-control study designed as an equivalence trial to evaluate if weightbearing radiographs predict whether stable/SER2 and partially unstable/SER4a Weber B ankle fractures reach union with preserved normal tibiotalar congruence and without a concomitant increase of treatment failure. A total of 149 patients with a Weber B fracture stable on weightbearing radiographs were recruited into the trial. All participants were treated with a functional orthosis and weightbearing allowed. Results from gravity stress radiographs classified ankles as SER2 or SER4a fracture types. We defined an equivalence margin in medial clear space difference of 1.0 mm. We also evaluated the reliability of obtaining measurements from weightbearing radiographs. RESULTS: No differences in medial clear space between the injured and uninjured ankles were observed after fracture union for the SER2 group (mean difference 0.1 mm, 95% confidence interval [CI] -0.3, 0.0; P = .056), or the SER4a group (mean difference 0.0 mm (95% CI -0.1, 0.1; P = .797). No between-group differences were observed (mean difference 0.0 mm, 95% CI -0.2, 0.2; P = .842). These findings were consistent with equivalence. CIs for the intraclass correlation coefficients indicated excellent reliability. CONCLUSION: Assessment of stability of Weber B SER2/4a ankle fractures, with weightbearing radiographs, also predicts preservation of normal ankle congruence in those deemed stable, with no difference between SER2 and SER4a fracture types. Further, excellent reproducibility of the method of obtaining medial clear space measurements was demonstrated. LEVEL OF EVIDENCE: Level III, case-control.