Plantar flexion influences radiographic measurements of the ankle mortise

Comparison of Outcomes at Midterm Follow-up of Operatively and Nonoperatively Treated Isolated Weber B Ankle Fractures

OBJECTIVES

A novel protocol was previously presented for nonoperative management of Weber B (OTA/AO 44B) ankle fractures with criteria of medial clear space <7 mm on gravity stress (GS) radiographs and ipsilateral superior clear space and contralateral GS medial clear space within 2 mm. This study recruited an operative cohort for comparison of outcomes.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Level 1 academic center.

PATIENT SELECTION CRITERIA

The recruited operative cohort consisted of patients who may have been considered for the nonoperative protocol, but underwent surgery instead.

OUTCOME MEASURES AND COMPARISONS

Kellgren-Lawrence scale for evaluation of arthritis, American Orthopedic Foot and Ankle Society Hindfoot, Olerud Molander Ankle, Lower Extremity Functional Scale (LEFS), and PROMIS (physical function, depression, pain interference) scores for the current operative cohort were compared with that of the original nonoperative cohort.

RESULTS

There were 20 patients in the operative cohort and 29 in the original nonoperative cohort. Mean follow-up was 6.9 and 6.7 years, respectively. The following outcome scores were better for the nonoperative cohort compared with the operative, respectively: LEFS, 75.2 and 68.1 ( P = 0.009); Olerud Molander Ankle, 94.1 and 89.0 ( P = 0.05); American Orthopedic Foot and Ankle Society, 98.5 and 91.7 ( P = 0.0003); PROMIS Physical Function, 58.2 and 50.4 ( P = 0.01); PROMIS Pain Interference, 42.2 and 49.7 ( P = 0.004). The PROMIS Depression, 42.8 and 45.4 ( P = 0.29), was not different between groups. All patients achieved union of their fracture. Surgical complications included implant removal (15%), SPN neurapraxia (5%), and delayed wound healing (5%).

CONCLUSIONS

In carefully selected patients with isolated Weber B fractures, nonoperative management may be considered because it can lead to equivalent or superior outcomes with none of the risks typically associated with surgical intervention.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Successful Outcomes With Nonoperative Treatment and Immediate Weightbearing Despite Stress-Positive Radiographs in Isolated Distal Fibula (OTA/AO 44B) Fractures

OBJECTIVES

To determine whether a nonoperative management protocol results in equivalent outcomes in isolated OTA/AO 44B (Weber B) fractures without initial medial clear space (MCS) widening regardless of stress radiography findings.

METHODS

DESIGN

Prospective cohort.

SETTING

Level 1 academic trauma center.

PATIENT SELECTION CRITERIA

Nonoperatively managed patients with isolated OTA/AO 44B fractures and MCS ≤4 mm on initial non-weightbearing injury radiographs between from January 2018 and January 2022 were included. All patients underwent emergency department gravity stress radiographs and those with widening were considered the widening cohort and those without the non-widening cohort.

OUTCOME MEASURE AND COMPARISONS

MCS measurements on weightbearing radiographs were obtained at first follow-up, 6 weeks, 12 weeks, and 6 months postinjury, were considered indicative of instability if >4 mm and were compared between cohorts.; American Orthopaedic Foot and Ankle Society ankle-hindfoot scores were also compared between cohorts.

RESULTS

Sixty-nine patients were studied. None of the 38 patients (55%) with widening on gravity stress radiographs demonstrated widening with weightbearing radiographs at any time point. Mean MCS measurement differences between the 2 cohorts were statistically significant for all time points ( P = 0.012); however, with a model adjusted mean MCS value of 2.7 mm for the nonwidening cohort and 2.9 mm for the widening cohort, these are not clinically significant. There was no statistically significant difference in overall final American Orthopaedic Foot and Ankle Society scores between the 2 groups ( P = 0.451). In addition, statistical equivalence using Schuirmann 2 one-sided tests was achieved between the 2 groups. Both cohorts had mean American Orthopaedic Foot and Ankle Society scores representing excellent outcomes at the final follow-up.

CONCLUSIONS

Patients with isolated OTA/AO 44B fractures without MCS widening on initial injury radiographs did not demonstrate instability on subsequent weightbearing radiographs and had equivalent outcomes regardless of gravity stress radiography findings when treated nonoperatively. Weightbearing radiographs at the initial follow-up appear to be a reliable assessment of ankle stability in these injuries and are an appropriate alternative to painful and time-consuming stress radiography.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Measuring Deltoid Insufficiency After Supination-External Rotation Ankle Fracture With Lateral Talar Subluxation on Gravity Stress View

BACKGROUND

Stress-view radiographs are frequently obtained to evaluate supination-external rotation (SER) variant ankle fractures. Measurement of the ankle medial clear space (MCS) is a surrogate of medial structure integrity as part of overall ankle stability. Measurement of the lateral talus displacement with respect to the incisura may be a sensitive and specific method to assess joint subluxation.

METHODS

Retrospective review of acute SER-variant isolated lateral malleolar fractures with gravity stress views (GSVs) were performed for 103 patients. GSV analysis was performed with standardized measurements of the MCS, superior clear space (SCS), and 2 new novel measurements of lateral talus subluxation (LTS). Decision for surgery was obtained by surgeons who reviewed masked injury radiographs for predictive performance analysis of the LTS vs MCS.

RESULTS

MCS, SCS, and LTS measurements were performed on 103 patients. Mean MCS, SCS, and LTS within the operative group was increased. MCS ≥5 mm and LTS >4 mm had equal sensitivity (95%), with higher specificity for LTS (75% vs 60%). Receiver operating characteristic analysis demonstrates an area under the curve of 0.786 for MCS ≥5 mm vs 0.918 for LTS >4 mm.

CONCLUSION

We found LTS to be superior to MCS for medial ankle structure stability on gravity stress views of SER-variant ankle fractures. We propose this as a useful tool for clinicians to consider when evaluating SER-variant ankle fractures.

LEVEL OF EVIDENCE

Level II, prospective comparative study of radiographs.

The effect of partial deltoid ligament injuries on the external rotation stability: A cadaveric study

BACKGROUND

The anterior and posterior part of the deltoid ligament have different functions during ankle flexion motion. Partial ligament injuries have been demonstrated in previous clinical reports. However, the efficacy of external rotation stress test in partial injured cases is unavailable till now.

METHODS

Thirty-two fresh cadaveric specimens were included and allocated into two destabilization groups. In the first group, the anterior portion of deltoid ligament (DL) and syndesmotic ligament were sequentially severed, while in the second group, the posterior portion of DL and syndesmotic ligament were sequentially severed. Mortise view radiographs were taken after each destabilization stage when the ankles were placed at plantarflexion and dorsiflexion positions and stressed in standard external rotation force. The medial clear space (MCS) and talar tilt (TT) angle were measured and compared among different destabilization stages.

RESULTS

When the ankles were placed at neutral position, the TT significantly increased in all destabilization stages. The MCS significantly increased after the partial deltoid ligament ruptures only with presence of syndesmotic ligament injuries. There was no significant difference of MCS at plantarflexion for all stages of destabilization if the anterior portion of DL is preserved. Similarly, no significant increase of MCS was detected at dorsiflexion if the posterior portion of DL and posterior inferior tibiofibular ligament are intact.

CONCLUSION

Partial DL rupture causes ankle rotational instability at different ankle joint positions, especially when combined with syndesmotic injuries. The neutral position is recommended for diagnosis of partial DL ruptures under external rotation stress.

Length change pattern of the ankle deltoid ligament during physiological ankle motion

BACKGROUND

Length change pattern of the ankle deltoid ligament during physiological ankle motion is still confused currently and had not been studied in vivo.

METHODS

The deltoid ligaments from 7 cadaveric specimens were dissected. Lengths of each band during 30° plantarflexion to 20° dorsiflexion were measured. A dual fluoroscopy imaging system was utilized to capture the images of hindfoot joint of 7 healthy subjects during the stance phase of walking. 3D bone models were reconstructed from CT images. Lengths of each band were calculated after model-image registration utilizing a solid modeling software. Percentage of length variation and poses when the bands were in maximum extension were documented among each band.

RESULTS

The anterior border of tibiocalcaneal ligament (TCL) had only 1.7% length variation in vitro and 5.7% length variation in vivo. The tibionavicular ligament, tibiospring ligament, and deep anterior tibiotalar ligament were in maximum extension at 30° plantarflexion, however, superficial posterior tibiotalar ligament, deep posterior tibiotalar ligament, and the posterior border of TCL were in maximum extension at 20° dorsiflexion. The tibionavicular ligament, tibiospring ligament, and deep anterior tibiotalar ligament were in maximum extension during foot flat. The TCL was in maximum extension during midstance. The superficial posterior tibiotalar ligament and deep posterior tibiotalar ligament were in maximum extension during heel off and toe off.

CONCLUSION

The length of TCL did not change during ankle dorsiflexion and plantarflexion. The bands anterior to and posterior to the TCL showed different length change pattern during physiological ankle dorsiflexion and plantarflexion.

Arthroscopic Quantitative Measurement of Medial Clear Space for Deltoid Injury of the Ankle: A Cadaveric Comparative Study With Stress Radiography

BACKGROUND

The deltoid ligament (DL) is an important stabilizer of the ankle. DL injury of varying severity can occur alone or with syndesmotic injury and fibular fracture. Limited diagnostic tools are available to assess DL injury quantitatively.

PURPOSE

To establish an arthroscopic quantitative assessment of DL injury and to compare its performance with that of external rotation stress (ERS) and gravity stress (GS) radiography.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 24 cadaveric lower extremities were divided into 4 groups: group 1 consisted of intact DL, group 2 of superficial DL disruption, group 3 of deep DL disruption, and group 4 of complete DL (superficial and deep) disruption. All specimens underwent sequential sectioning of syndesmotic ligaments, and medial clear space (MCS) was measured with ankle arthroscopy, ERS radiography, and GS radiography at different stages of syndesmotic sectioning.

RESULTS

For noninjured deltoid (group 1) and injured deltoid (groups 2-4), area under the receiver operating characteristic curve (AUC) of measurement of MCS was 0.939 for arthroscopy, 0.932 for ERS radiography, and 0.874 for GS radiography, with a significant difference between arthroscopy and GS radiography (P = .014). For incomplete deltoid injury (groups 1-3) and complete deltoid injury (group 4), the AUC of MCS was 0.811 for arthroscopy, 0.656 for ERS radiography, and 0.721 for GS radiography, with a significant difference between arthroscopy and ERS radiography (P < .001) and between arthroscopy and GS radiography (P = .035). For all stages of syndesmotic sectioning, cutoff values of arthroscopic MCS with intact fibula were ≤2.5 mm for intact DL, between 2.5 and 3.5 mm for partial DL injury (superficial or deep), and ≥3.5 mm for complete DL injury. Arthroscopy was unable to detect a difference between superficial deltoid injury (group 2) and deep deltoid injury (group 3) in partial DL injury, with a measured MCS between 2.5 and 3.5 mm. The intraclass correlation coefficient of interrater reliability was 0.975 for arthroscopy, 0.917 for ERS radiography, and 0.811 for GS radiography.

CONCLUSION

Arthroscopic MCS measurement can differentiate intact DL, partial DL injury, and complete DL injury. Compared with ERS and GS radiography, arthroscopic MCS measurement has greater accuracy with excellent interrater reliability.

CLINICAL RELEVANCE

For patients with suspected DL injury, arthroscopic MCS is useful for determining deltoid lesion severity based on defined cutoff values for consideration in preoperative planning to improve surgical outcomes.

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.

Correlating Arthroscopic and Radiographic Findings of Deep Deltoid Ligament Injuries in Rotational Ankle Fractures

BACKGROUND

The deep deltoid ligament (DDL) is a key stabilizer to the medial ankle and ankle mortise and can be disrupted in ligamentous supination external rotation type IV (LSER4) ankle fractures. The purpose of this study was to define the medial clear space (MCS) measurement on injury mortise radiographs that corresponds with complete DDL injury.

METHODS

A retrospective record review at a level 1 hospital was performed identifying patients with LSER4 ankle fractures who underwent arthroscopy and open reduction internal fixation. Chart reviews provided arthroscopic images and operative reports. Complete DDL injury was defined as arthroscopic visualization of the posterior tibial tendon (PTT). Inability to completely visualize the PTT was defined as a partial DDL injury. MCS was measured on injury mortise radiographs. Eighteen subjects met inclusion criteria.

RESULTS

Twelve subjects had complete and 6 subjects had partial DDL injury based on arthroscopic findings. Patients with complete DDL injury and those with partial DDL injury had injury radiograph MCS ranging from 5.5 to 29.9 mm and 4.0 to 5.0 mm, respectively. All patients with MCS ≥5.5 mm on injury radiographs had complete DDL injury and all patients with MCS ≤5.0 mm on injury radiographs had partial DDL injury.

CONCLUSION

Complete DDL injury was found on injury ankle mortise radiographs as MCS widening of ≥5.5 mm, which correlated with arthroscopic visualization of the PTT. Using this cutoff, surgeons can surmise the presence of a complete deltoid ligament injury, allowing for improved preoperative planning.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Strategies to Avoid Syndesmosis Malreduction in Ankle Fractures

Nearly half of surgically treated ankle fractures may have associated syndesmotic disruption, and the quality of reduction has been shown to affect functional outcomes. Malreduction ranges from 15% to 50% in the literature, and achieving anatomic reduction remains a significant challenge, even for experienced surgeons. Keys to success include having a stepwise plan and an understanding of reliable fluoroscopic parameters to help achieve reduction in both the coronal and sagittal planes. This article summarizes the literature on syndesmotic reduction and provides the authors' preferred technique using fluoroscopy.

Effect of Muscle Activation on the Gravity Stress View in Unstable Weber B Ankle Fractures

BACKGROUND

In the setting of apparently isolated distal fibula fractures, the gravity stress view (GSV) is a validated method to determine mortise stability. There is currently no published data evaluating whether dynamic muscle activation can reduce an unstable mortise. If patients with instability can overcome gravity, resultant images could yield false-negative results. The goal of this investigation was to determine if patient effort can influence medial clear space (MCS) measurements in proven unstable bimalleolar-equivalent ankle fractures.

METHODS

Patients presenting with Weber B fibula fractures were assessed for mortise stability using the GSV. If the GSV demonstrated instability based on MCS widening >4 mm, 3 additional views were performed: GSV with an assistant maintaining the ankle in a neutral position; GSV with the patient actively dorsiflexing to neutral; and GSV with the patient actively dorsiflexing and supinating the foot. Twenty-four consecutive patients met inclusion criteria, with a mean age of 48.7 (range, 22-85) years. Fifteen patients (62.5%) were female and 9 (37.5%) were male. The laterality was evenly divided.

RESULTS

The mean MCS was 5.8 ± 2.0 6.0 ± 2.6, and 6.2 ± 2.7 mm for the manual assist, active dorsiflexion, and active supination radiograph measurement groups, respectively (P = .434). Only 5 of 24 subjects had any measurable decrease in their MCS with active supination, with a maximum change of 1.2 mm. The remainder of the patients had an increase in MCS ranging from 0.1 to 4.0 mm.

CONCLUSION

There was no significant difference between measurement states indicating that muscle activation is unlikely to yield a false-negative result on GSV. Mortise instability, secondary to deep deltoid injury in the presence of gravity stress, is unlikely to be actively overcome by dynamic stabilizers, supporting the validity and specificity of the GSV.

LEVEL OF EVIDENCE

Level III, prospective study.

Reliability of Postoperative Radiographies in Ankle Fractures

Background

The accuracy of reduction of ankle fractures using postoperative plain radiographies (x-ray) remains widely controversial. Some authors have demonstrated that postoperative computed tomography (CT) scan can be useful for these patients. In current study, the efficacy of x-rays after fixation of ankle fractures was investigated based on the CT scan findings.

Methods

A total of 73 patients with ankle fractures who were subjected to open reduction internal fixation (ORIF) were enrolled. After surgery, if the reduction was acceptable based on the x-rays according to standard measurements, the patient was referred for CT scanning. Forty four patients were included in the study. Undesirable CT scan findings including malreduction of fragments or articular surfaces, device malpositioning, missed fractures, and undetected intra-articular fragments were documented.

Results

Undesirable CT findings were seen in 25 patients (56.8%). CT scan showed acceptable reduction without device malpositioning in 19 patients. The most prevalent findings in CT images were malreduction and device malpositioning in 17 and 16 patients, respectively. There was no abnormal finding in CT imaging of lateral malleolar fractures. In two thirds of the injured syndesmosis, device malpositioning, and malreduction were detected in CT scan.

Conclusion

Despite acceptable postoperative x-rays, a considerable number of patients with ankle fractures had inappropriate reduction or undesirable findings in their postoperative CT scan. It seems necessary to use CT scan after ORIF of ankle fractures in order to examine the accuracy of reduction. Further validation of postoperative CT scan in ankle fracture surgery should be investigated.

Acute and Chronic Syndesmotic Instability: Role of Surgical Stabilization

Acute and chronic syndesmotic injuries significantly impact athletic function and activities of daily living. Patient history, examination, and judicious use of imaging modalities aid diagnosis. Surgical management should be used when frank diastasis, instability, and/or chronic pain and disability ensue. Screw and suture-button fixation remain the mainstay of treatment of acute injuries, but novel syndesmotic reconstruction techniques hold promise for treatment of acute and chronic injuries, especially for athletes. This article focuses on anatomy, mechanisms of injury, diagnosis, and surgical reduction and stabilization of acute and chronic syndesmotic instability. Fixation methods with a focus on considerations for athletes are discussed.

Medial tenderness revisited: Is medial ankle tenderness predictive of instability in isolated lateral malleolus fractures?

INTRODUCTION

Determining deltoid ligament incompetence in supination external rotation (SER) injuries commonly relies on stress radiography, given several studies demonstrating low predictive value of physical examination. Stress radiography can be difficult to obtain and may result in suboptimal radiographs with equivocal determination of stability. This study revisits the concept of medial ankle tenderness and its association with mortise instability.

METHODS

Patients who presented with an isolated lateral malleolus fracture underwent prospective data collection. VAS scores were recorded with palpation at the lateral malleolar fracture site, anterior deltoid ligament, and posterior deltoid ligament. Three non-weightbearing radiographs of the ankle and a gravity stress view were obtained. Statistical analysis was performed to determine a correlation between tenderness and instability defined as MCS widening > 4 mm on gravity stress x-ray.

RESULTS

51 patients met inclusion criteria. Group I (stable) and Group II (unstable) demonstrated no difference in tenderness over the lateral malleolus (p = 0.94) or anterior deltoid (p = 0.12), but patients in Group II reported significantly more tenderness over the posterior deltoid (p = 0.03). Taking the higher pain score from either anterior or posterior deltoid palpation, patients with unstable ankle fractures reported significantly more tenderness with medial palpation (p = 0.02). The relative risk of having an unstable ankle fracture with any tenderness to palpation over either the anterior or posterior deltoid ligament was 1.77 (95% CI 1.03 - 3.06, P = 0.039). When comparing no pain versus the presence of any pain with palpation medially, the sensitivity for any medial tenderness to detect an unstable ankle fracture was 0.76 (specificity 0.59, PPV 0.79, NPV 0.56).

CONCLUSION

Patients with any medial tenderness were at significantly higher risk of having an unstable SER ankle fracture in this study, but strict reliance on the presence or absence of medial tenderness without stress radiographs would lead to an unacceptable number of both false positive and false negative determinations of instability. However, our findings suggest that medial tenderness is associated with instability. The 0.79 PPV of any medial tenderness for instability may be useful to cast doubt on equivocal stress radiography and prompt surgeons to repeat stress radiography or shorten the interval for radiographic follow up.

LEVEL OF EVIDENCE

Diagnostic study, Level II-1 (development of diagnostic criteria on basis of consecutive patients [with universally applied reference "gold" standard]).

Ankle stability in ankle fracture

Restoration of normal ankle kinematics should be the all-encompassing ethos in the approach to management of ankle fractures. To do this, the ligamentous stabilisers must also form part of its assessment and definitive management and be considered during index fracture fixation surgery. This article is a review of the anatomy, mechanics and clinical testing of instability in ankle fractures.

Immediate Weight-Bearing Protocol for the Determination of Ankle Stability in Patients With Isolated Distal Fibular Fractures

OBJECTIVE

To evaluate an alternative protocol for allowing immediate weight-bearing (WB) as tolerated in a functional walking boot in patients with a medial clear space (MCS) of less than 4 mm on nonstressed initial radiographs with subsequent WB radiographs at 1-week follow-up to determine if this can differentiate stable from unstable distal fibular fractures.

DESIGN

Retrospective case series.

SETTING

Level 1 trauma center.

PATIENTS

Seventy-nine patients who sustained an isolated distal fibular fracture with an MCS less than 4 mm on initial non-weight-bearing radiographs during a 6-year period.

INTERVENTION

Patients with MCS less than 4 mm on 1-week radiographs were treated nonoperatively. Patients with MCS greater than or equal to 4 mm were treated operatively.

MAIN OUTCOME MEASUREMENTS

Medial clear space measurements on WB ankle radiographs at the time of radiographic bony union.

RESULTS

Two of the 79 (2.5%) patients had an MCS greater than 4 mm at 1-week follow-up with WB radiographs and underwent operative fixation. The remaining 77 patients were treated nonoperatively. All 77 patients had an MCS less than 4 mm on WB radiographs at the time of radiographic healing.

CONCLUSION

These results suggest that our immediate weight-bearing protocol may be an effective method for determination of functional ankle stability only in the setting of an isolated distal fibula fracture with MCS less than 4 mm. However, it should be cautioned that careful evaluation of WB radiographs for joint asymmetry and/or MCS widening is mandatory to avoid poor outcomes.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Morphology of the Incisura Fibularis at the Distal Tibiofibular Syndesmosis in the Japanese Population

The morphology of the distal tibiofibular syndesmosis can determine the pathology and mechanism of syndesmotic injury. The present study assessed measurements obtained from computed tomography (CT) images of the normal distal tibiofibular syndesmosis in Japanese subjects. CT scans of 120 right feet with a normal distal tibiofibular syndesmosis obtained from January 2009 to December 2016 were retrospectively assessed at the level 10 mm proximal to the tibial plafond. The incisura fibularis was considered concave when its depth was ≥4 mm and shallow when its depth was <4 mm. The depth of the incisura fibularis, anterior tibiofibular distance (TFD), posterior TFD, and longitudinal/transverse length of the distal fibula were measured. The incisura fibularis was concave in 64.2% of the feet and shallow in 35.8%. The mean anterior TFD was 2.2 ± 0.8 mm (2.4 ± 0.8 mm in males; 2.1 ± 0.8 mm in females; 2.1 ± 0.8 mm for concave; 2.2 ± 0.9 mm for shallow). The mean posterior TFD was 5.9 ± 1.6 mm (6.7 ± 2.1 in males; 5.7 ± 1.3 mm in females; 5.5 ± 1.3 mm for concave; 6.5 ± 1.9 mm for shallow). The mean longitudinal/transverse length of the distal fibula at the level of the syndesmosis was 1.2 mm (1.3 mm in males; 1.2 mm in females; 1.1 mm for concave; 1.3 mm for shallow). The mean posterior TFD was significantly greater than the mean anterior TFD and was also significantly greater in males than in females. Significant differences were found in the body mass index, posterior TFD, and longitudinal/transverse length of the distal fibula according to whether the incisura fibularis was concave or shallow. The present study has provided measurements of the normal tibiofibular syndesmosis in the Japanese population. These data suggest that the morphology of the syndesmosis varies, especially with respect to whether the incisura fibularis is concave or shallow.

Does Foot Position and Location of Measurement Influence Ankle Medial Clear Space?

PURPOSE

There is still controversy regarding normal and abnormal values of the medial clear space (MCS) of the ankle. The aim of this study was to assess how much different degrees of plantar flexion, with and without stress, influenced the MCS.

METHODS

We submitted 30 volunteers to 6 different anteroposterior ankle radiographs in the following positions: neutral, neutral with external rotation stress, physiologic plantar flexion (FPF), physiologic plantar flexion with external rotation stress, maximum plantar flexion (MPF), and maximum plantar flexion with external rotation stress. The MCS oblique (MCSo) and perpendicular (MCSp) were measured in all images by an experienced foot and ankle surgeon.

RESULTS

The data showed that the position of the foot does influence the value of MCSp and MCSo ( P < .05), except for 3 comparisons. MCSo did not change between FPF with stress and MPF with stress. MCSp did not change in 2 situations: between FPF and neutral with stress and between MPF and FPF with stress.

CONCLUSIONS

This study is unique in showing that different ways of positioning the foot and performing stress radiographs results in different MCS values and that these values differ depending on the anatomical site where they are measured.

LEVELS OF EVIDENCE

Diagnostic, Level IV.

Relationship of Self-Reported Ability to Weight-Bear Immediately After Injury as Predictor of Stability for Ankle Fractures

BACKGROUND

Determining the stability of ankle fractures, particularly Weber B fibula fractures, can be challenging. Ability to weight-bear after injury may be predictive of stability. We sought to determine whether patients' ability to weight-bear immediately after injury was an effective indicator for ankle stability following fracture.

METHODS

A prospective review was conducted of patients sustaining ankle fractures. Patients' ability to weight-bear after injury was elicited and correlated with ankle radiographs, which were deemed stable or unstable based on commonly used indices to assess stability.

RESULTS

For the entire cohort (n = 121), patients who were able to weight-bear immediately after injury were over 8 times more likely to have a stable fracture than those who could not (odds ratio [OR] = 8.6, P < .001). Positive predictive value (PPV) for being able to fully weight-bear as it related to stability was 73%. Inability to weight-bear was 85% specific among patients with an unstable fracture. When analyzing patients with radiographic isolated fibula fractures (n = 67), PPV = 82%, negative predictive value [NPV] = 53%, specificity = 79%, whereas the OR was 5.0 (P = .003) for those who could weight-bear having a stable fracture. When subanalyzing patients who presented with isolated fibula fractures and anatomic mortises (n = 43), PPV = 74%, NPV = 52%, specificity = 62%, whereas the OR was 3.6 (P = .07) for those who could weight-bear having a stable fracture.

CONCLUSION

Patients' ability to weight-bear immediately after injury was a specific and prognostic indicator for stability across a range of ankle fracture subtypes. Patients with an isolated fibula fracture and anatomic mortise were 3.6 times more likely to have a stable fracture if they were able to fully weight-bear at the time of injury. Although a patient's history does not preclude the need for appropriate imaging studies and clinical judgment, it may aid in the assessment of ankle stability following fracture.

LEVEL OF EVIDENCE

Level II, clinical diagnostic.

A Novel Algorithm for Isolated Weber B Ankle Fractures: A Retrospective Review of 51 Nonsurgically Treated Patients

INTRODUCTION

Stability of isolated Weber B ankle fractures can be difficult to determine. Using weight-bearing radiographs, a reliable method to determine the stability of isolated Weber B ankle fractures is described.

METHODS

A retrospective review of prospectively gathered data was performed. Weber B ankle fractures were defined as stable when having a medial clear space (MCS) of <7 mm on initial gravity stress radiographs and a normal mortise relationship on weight-bearing radiographs. Fifty-one patients meeting these criteria were treated nonsurgically with protected weight bearing and serial radiography for 1 year.

RESULTS

Average functional score results were: American Orthopaedic Foot and Ankle Society Hindfoot, 93.2; Foot and Ankle Ability Measure for Activities of Daily Living, 93.2; Olerud-Molander Ankle Score, 91.0; and visual analog scale pain score, 0.57. Despite a mean gravity stress MCS of 4.42 mm, no patient demonstrated subsequent MCS widening. Mean MCS on 1-year follow-up weight-bearing radiographs was 2.64 mm.

CONCLUSION

Weight-bearing ankle radiographs are predictive of stability in isolated Weber B ankle fractures. Gravity stress radiographs using traditional measurement criteria may overestimate instability in these injuries. Nonsurgical treatment with protected weight bearing shows good early outcomes.

LEVEL OF EVIDENCE

IV.

Predictors of a persistent dislocation after reduction of syndesmotic injuries detected with intraoperative three-dimensional imaging

BACKGROUND

In about 25% of cases, reduction of acute unstable syndesmotic injuries and stabilization with syndesmotic screws leads to an inadequate reduction. Conventional fluoroscopy does not provide reliable information about the reduction outcome. However, use of intraoperative 3D imaging can be more accurate. The purpose of this study was to identify predictors of inadequate reduction so that the need for intra- or postoperative 3D imaging could be assessed. Our hypothesis was that complex injuries of the syndesmosis present a higher risk of malreduction than simpler ankle fractures.

METHODS

From August 2001 to February 2011, 251 unstable syndesmotic injuries were treated from a total of 2286 ankle fractures. In 61 of these cases, malreduction of the fibula into the fibular notch was detected by intraoperative 3D imaging. The influence of all possible concomitant and combination injuries of the ankle joint, surgeon's experience, and potential implant-related effects was analyzed.

RESULTS

Thirty-seven Weber C fractures (60.7%), 13 Maisonneuve fractures (21.3%), 10 Weber B fractures (16.4%), and 1 syndesmotic injury without fracture (1.6%) were included. In 14 cases (23%) there was involvement of the posterior malleolus, in 10 cases of the medial malleolus (16.4%), and in 12 cases both (19.7%). The Weber C fractures included 10 bimalleolar fractures with involvement of the posterior malleolus. In neither this combination nor in any other possible injury configuration was it possible to identify a statistically significant correlation with malreduction of the fibula into the fibular notch. The surgeon's experience or an implant-related effect had no detectable influence either.

CONCLUSION

Based on the factors studied, it is not possible to conclude whether a patient has an increased risk of malreduction. Therefore we still recommend verifying all reduction outcomes by intraoperative 3D imaging or postoperative computed tomography.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Relationship among radiographic ankle medial clear space, sex, and height

The ankle medial clear space (MCS) is frequently measured to evaluate ankle stability after an injury. However, controversy exists regarding a threshold size that distinguishes a normal MCS from an abnormal MCS. A retrospective radiographic review of mortise ankle radiographs in the uninjured ankle was performed, with the goal of defining the relationship among patient height, sex, and radiographic ankle MCS. Forty-nine patients with normal mortise radiographs and with information on patient height available in the electronic medical chart were identified for inclusion. For men, mean±standard deviation (in millimeters) was 3.3±0.8 for MCS perpendicular (MCSp), 3.8±0.7 for MCS oblique (MCSo), and 3.8±0.5 for superior clear space (SCS). For women, mean±standard deviation was 2.3±0.6 for MCSp, 2.9±0.5 for MCSo, and 3±0.4 for SCS. Univariate analysis showed that all 3 variables (MCSp, MCSo, and SCS) were statistically different when men were compared with women (P<.0001). Bivariate regression models showed statistically significant (P<.001) positive relationships between each of the measures of clear space and height. In multivariate analysis, female sex alone was associated with a decrease in clear space. When evaluating isolated lateral malleolus fractures, clinicians should consider the patient's height and sex when measuring MCS and SCS to determine deltoid ligament competence. These data suggest that men and people of tall stature are at risk for a false-positive diagnosis of deltoid ligament rupture when previously published threshold MCS and SCS values, such as 4 mm or 5 mm, are used for diagnosis and operative indication.

Varus external rotation stress test for radiographic detection of deep deltoid ligament disruption with and without syndesmotic disruption: a cadaveric study

BACKGROUND

External rotation stress is used intraoperatively for diagnosing medial ankle and syndesmotic instability in rotational ankle fractures after reduction and fixation of the fibula. However, external rotation includes hindfoot, midfoot, and ankle motion. The purpose of this study was to determine the effect of hindfoot positioning when using the external rotation stress test. Isolated deep deltoid ligament (DDL) instability and combined DDL and syndesmotic instability were modeled. An intact fibula was used as a surrogate for an anatomically fixed fibula fracture.

METHODS

Six cadaver specimens with full-length tib-fib articulations were used. Specimens were fixed into a Taylor Spatial Frame (Smith&Nephew, Memphis, TN) with 4 to 5 points of fixation in the tibia and the foot. Specimens were mounted in ankle and foot neutral position. Metal markers were placed at the medial gutter and syndesmosis. Anteroposterior (AP) and mortise radiographs were obtained in 3 positions: neutral hindfoot, valgus external rotation stress, and varus external rotation stress. For both valgus and varus external rotation stress, the frame was loosened and stressed to a hard end point and then locked. Three modes were studied: intact ligaments, DDL transected, and DDL+ syndesmosis transected. Digital radiographs were used to measure the displacement of the markers.

RESULTS

The varus external rotation stress test demonstrated significant widening of the medial gutter in specimens with isolated DDL instability, in both AP (P = .01) and mortise (P = .02) views. Both maneuvers demonstrated significant medial gutter widening with combined DDL and syndesmosis disruption (P ≤ .01), although the varus external rotation stress test produced nearly twice as much displacement (10.7 vs 5.4 mm). Syndesmotic widening was not significant with either maneuver.

CONCLUSIONS

Varus external rotation stress was more effective than valgus external rotation stress in demonstrating displacement of markers at the medial gutter and on AP and mortise radiographs for both DDL and DDL with syndesmotic instability.

CLINICAL RELEVANCE

These findings may lead to improved clinical detection of rotational ankle instability from combined DDL and syndesmotic disruption, which may affect decision making for using syndesmotic fixation when using intraoperative stress fluoroscopy images. Occult DDL instability may be underdiagnosed, and this may affect future directions of the treatment of rotational ankle fractures and severe sprains.

Variability in radiographic medial clear space measurement of the normal weight-bearing ankle

BACKGROUND

Medial clear space (MCS) width on mortise radiographs of the ankle is commonly used by clinicians for determining the competence of the deltoid ligament in the Weber B supination-external rotation ankle fracture. Significant variability exists in the current literature regarding methods of obtaining this measure and definition of a normal measure in comparison with a pathologic state.

METHODS

Seventy-three paired bilateral ankle mortise radiographs that were without ankle pathology were retrospectively reviewed. MCS width at two separate locations (oblique and perpendicular) and superior clear space (SCS) were measured on digital radiographs. A Student's t test was used to compare mean values.

RESULTS

Mean values (± SD) were 3.2 (± 0.7)~mm for MCS oblique, 2.6 (± 0.7)~mm for MCS perpendicular, and 3.3 (± 0.6)~mm for SCS. A significant difference (p < .001) existed for all three measures between males and females. MCS oblique was statistically different than MCS perpendicular (p < .001) for all patients and for males and females independently. The mean difference between paired bilateral radiographs was 0.3 (± 0.2)~mm for MCS oblique, 0.6 (± 0.6)~mm for MCS perpendicular, and 0.2 (± 0.2)~mm for SCS.

CONCLUSIONS

MCS width has variability based on the location chosen for measurement and gender. Contralateral radiographic comparison of MCS should be routinely used to identify pathologic widening versus normal anatomic variation.

CLINICAL RELEVANCE

Use of single threshold values for MCS width as an operative indicator may produce a false-positive diagnosis of deltoid incompetence in Weber B supination-external rotation ankle fractures and possibly lead to unnecessary surgery.

What's new in foot and ankle surgery

This update summarizes recent research pertaining to the subspecialty of orthopaedic foot and ankle surgery that was published or presented between August 2009 and July 2010. The sources of these studies include The Journal of Bone and Joint Surgery (American and British Volumes), Foot & Ankle International, and the proceedings of Specialty Day at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS), held on March 13, 2010, in New Orleans, Louisiana, and the summer meeting of the American Orthopaedic Foot & Ankle Society (AOFAS), held on July 7 through 10, 2010, in National Harbor, Maryland.