Mohammad Ghorbanhoseini

The Hindfoot Arch: What Role Does the Imager Play?

Flatfoot deformity is a common disorder of the foot and ankle and is caused by loss of the hindfoot arch. Radiologists and clinicians should be familiar with the anatomy and the imaging criteria used to assess injury to the supporting structures. Radiographs and computed tomography are most useful in characterizing the degree of osseous deformity and ultrasonography and magnetic resonance imaging are most useful in the evaluation of the supporting soft tissue structures. Treatment depends on the clinical symptoms and involves restoring the normal biomechanics of the hindfoot arch through strengthening exercises, foot/ankle orthotics, and surgery.

Overtightening of the syndesmosis revisited and the effect of syndesmotic malreduction on ankle dorsiflexion

BACKGROUND Ankle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws. The purposes of the current investigation are: (1) To assess the effect of compressive syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of motion. (2) To assess the effect of anterior & posterior syndesmotic malreduction after compressive syndesmotic screw fixation on ankle dorsiflexion. MATERIAL AND METHODS Fifteen lower limb cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro-sensor system after application of a consistent load in the (1) intact state, (2) after compression fixation with a syndesmotic screw and (3) after anterior & (4) posterior malreduction of the syndesmosis. RESULTS Following screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7±0.87% (mean±standard error) of baseline ankle ROM. Anterior and posterior malreduction of the syndesmosis resulted in dorsiflexion ROM that was 99.1±1.75% and 98.6±1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value=0.88). Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value=0.99). CONCLUSION Maximal dorsiflexion of the ankle is not required prior to syndesmotic fixation as no loss of motion was seen with compressive fixation in our cadaver model. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation had no effect on ankle dorsiflexion. Poor patient outcomes after syndesmotic malreduction may be due to other factors and not loss of dorsiflexion motion. LEVEL OF EVIDENCE IV.

Accuracy and Measurement Error of the Medial Clear Space of the Ankle

Background: Measurement of the medial clear space (MCS) is commonly used to assess deltoid ligament competency and mortise stability when managing ankle fractures. Lacking knowledge of the true anatomic width measured, previous studies have been unable to measure accuracy of measurement. The purpose of this study was to determine MCS measurement error and accuracy and any influencing factors. Methods: Using 3 normal transtibial ankle cadaver specimens, deltoid and syndesmotic ligaments were transected and the mortise widened and affixed at a width of 6 mm (specimen 1) and 4 mm (specimen 2). The mortise was left intact in specimen 3. Radiographs were obtained of each cadaver at varying degrees of rotation. Radiographs were randomized, and providers measured the MCS using a standardized technique. Results: Lack of accuracy as well as lack of precision in measurement of the medial clear space compared to a known anatomic value was present for all 3 specimens tested. There were no significant differences in mean delta with regard to level of training for specimens 1 and 2; however, with specimen 3, staff physicians showed increased measurement accuracy compared with trainees. Conclusion: Accuracy and precision of MCS measurements are poor. Provider experience did not appear to influence accuracy and precision of measurements for the displaced mortise. Clinical Relevance: This high degree of measurement error and lack of precision should be considered when deciding treatment options based on MCS measurements.

Superior Tuber Displacement in Intra-articular Calcaneus Fractures

Background: Intra-articular calcaneus fractures result in heel shortening, widening, varus malalignment, and loss of height. Little has been written regarding superior displacement of the calcaneal tuber, which warrants consideration as previous literature has demonstrated issues arising from a shortened triceps surae. We sought to determine the amount of tuber elevation seen in calcaneus fractures as compared to normal calcanei and propose 2 new measurements that aid in quantifying displacement and may aid in the surgical management of calcaneus fractures. Methods: Lateral radiographs of 220 normal calcanei were examined. Two novel measurements, the talo-tuber angle and talo-tuber distance, were used to establish normative data for calcaneal tuber positioning. Lateral radiographs of 50 calcaneus fractures treated operatively were examined and the same measurements were obtained before and after surgery to determine the amount of superior tuber elevation. Results: Normative data demonstrated a mean of 38.6 degrees (±SD = 4.3, range: 26.2-58.4) when using the talo-tuber angle and 54.5 mm (±SD = 7.3, range: 36.2-72.6) when using the talo-tuber distance in normal calcanei. Patients sustaining calcaneus fractures demonstrated a mean of 29.5 degrees (±SD = 5.9, range: 20-46.4) for the talo-tuber angle and 39.0 mm (±SD = 9.4, range: 24.0-62.9) for the talo-tuber distance. These values changed to a mean of 37 degrees (±SD = 5.2, range: 26.4-50) for the talo-tuber angle and 51.8 mm (±SD = 8.6, range: 33.2-75.7) for the talo-tuber distance after surgery. There was a statistically significant difference (P value < .01) for both talo-tuber angle and distance between normal and fractured calcanei. Inter- and intra-observer agreement was excellent. Conclusion: Superior displacement of the calcaneal tuber is a deformity seen in intra-articular calcaneus fractures that has been poorly described that warrants increased awareness and correction at the time of surgery. We propose 2 novel measurements with associated normative data that may aid surgeons in quantifying this deformity and assessing anatomic reduction. Level of Evidence: Level III, comparative study.

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.

Proximity of the Lateral Calcaneal Artery With a Modified Extensile Lateral Approach Compared to Standard Extensile Approach

Background: The extensile lateral approach (EL) has been associated with increased wound complications such as apical necrosis which may be due partially from violation of the lateral calcaneal artery (LCA). Traditionally, the vertical limb has been placed half-way between the fibula and Achilles tendon, which may be suboptimal given the proximity to the LCA. We hypothesized that placing the vertical limb further posterior (ie, modified EL [MEL]) would increase the distance from the LCA. The purposes of this study were to quantify the location of the LCA in relation to the vertical limb of the traditional EL approach and to determine if utilizing the MEL approach endangered the LCA to a lesser extent. Methods: 20 cadavers were used. For the EL approach, the fibula and Achilles tendon were palpated and a line parallel to the plantar foot was drawn between the two. A vertical line (VL), representing the vertical limb of the approach, was drawn at the midway point as a perpendicular extending proximally from the junction of the glabrous/non-glabrous skin (JGNG). For the MEL approach, the anterior border of the Achilles tendon was palpated and a similar vertical line (MVL) was drawn 0.75 cm anterior. Dissection was performed and if the LCA was identified crossing the line VL/MVL, the distance from the JGNG was documented. Results: For the EL approach, the LCA was identified in 17/20 (85%) cadavers at an average distance of 5.0 cm (range 3-7 cm, SD = 1.3 cm) from JGNG. For the ML approach, the LCA was identified in 4/20 (20%) cadavers at an average distance of 5.9 cm (range 3-6.5 cm, SD = 1.7 cm) from the JGNG (P < .001). Conclusions: The LCA was encountered 4 times more often during the EL approach as compared to the MEL approach. Clinical Relevance: A modification of the EL approach may decrease iatrogenic injury to the LCA and may decrease wound complications.

Different References for Valgus Cut Angle in Total Knee Arthroplasty

Background The valgus cut angle (VCA) of the distal femur in Total Knee Arthroplasty (TKA) is measured preoperatively on three-joint alignment radiographs. The anatomical axis of the femur can be described as the anatomical axis of the full length of the femur or as the anatomical axis of the distal half of the femur, which may result in different angles in some cases. During TKA, the anatomical axis of the femur is determined by intramedullary femoral guides, which may follow the distal half or near full anatomical axis, based on the length of the femoral guide. The aim of this study was to compare using the anatomical axis of the full length of the femur versus the anatomical axis of the distal half of the femur for measuring VCA, in normal and varus aligned femurs. We hypothesized that the VCA would be different based upon these two definitions of the anatomical axis of the femur. Methods Full-length weight bearing radiographs were used to determine three-joint alignment in normal aligned (Lateral Distal Femoral Angle; LDFA = 87º ± 2º) and varus aligned (LDFA >89º) femurs. Full-length anatomical axis-mechanical axis angle (angle 1) and distal half anatomical axis-mechanical axis angle (angle 2) were measured in all subjects by two independent orthopedic surgeons using a DICOM viewer software (PACS). Angles 1 and 2 were compared in normal and varus aligned subjects to determine whether there was a significant difference. Results Ninety-seven consecutive subjects with normally aligned femurs and 97 consecutive subjects with varus aligned femurs were included in this study. In normally aligned femurs, the mean value of angle 1 was 5.05° ± 0.76° and for angle 2 was 3.62° ± 1.19°, which were statistically different (P= 0.0001). In varus aligned femurs, the mean value of angle 1 was 5.42° ± 0.85° and for angle 2 was 4.23° ± 1.27°, which were also statistically different (P= 0.0047). Conclusion The two different methods of outlining the anatomical axis of the femur lead to different results in both normal and varus-aligned femurs. This should be considered in determination of the valgus cut angle on pre-operative radiographs and be adjusted according to the length of the intramedullary guide.

Iatrogenic fracture gapping during fixation of Jones fractures: Anatomic and mechanical considerations in a cadaveric model

BACKGROUND Surgical fixation of Jones fractures is often recommended to facilitate recovery and achieve union. Iatrogenic fracture displacement during intramedullary screw fixation is a commonly encountered technical issue. This may be related to fracture location in relation to the surrounding ligamentous attachments, namely the robust intermetatarsal ligaments found at the proximal articulation of the 4th and 5th metatarsals. This study examines the relationship between fracture line and its location in regards to the surrounding ligamentous structures and its effect on Jones fracture displacement, reduction and fixation in a cadaveric model. METHODS Eighteen fresh-frozen cadaveric feet were dissected with preservation of all ligamentous attachments. Given the similar anatomic distal extent of the dorsal and plantar intermetatarsal ligaments on the 5th metatarsal, measurements were obtained detailing the anatomic position of the dorsal intermetatarsal ligament (DIL) only. The specimens were divided into two groups with modelled fractures created at the 4th & 5th metatarsal articulation proximal to the distal extent of the DIL (Group 1) or just distal to the DIL (Group 2). Fractures were fixed in standard fashion with serial fluoroscopic images obtained to study fracture gapping and rotation. RESULTS There was approximately 5 mm of fracture gapping created iatrogenically during tapping with no statistically significant differences between Group 1 and Group 2 (4.53 mm versus 5.25 mm, p = 0.5430). The distal aspect of the DIL was anatomically located 2.77 mm (Range 1.58 mm-4.46 mm) distal to the 4th & 5th metatarsal articulation. CONCLUSIONS Considerable iatrogenic fracture gapping occurs during intramedullary screw fixation of Jones fractures in a cadaveric model regardless of fracture location in relation to the intermetatarsal ligamentous attachments. Specific techniques may be required to maintain anatomic alignment during tapping and screw fixation to prevent iatrogenic displacement. LEVEL OF EVIDENCE V, Expert Opinion.

Potential for Bias and the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scoring System

Background: The American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scoring System (AOFAS-AH) has not been validated and has significant risk for researcher bias, given that 40 out of 100 points are assessed by study staff subjectively. The purpose of this study is to evaluate its recent use in the orthopaedic literature to determine the percentage of previously published studies for which study conclusions would be changed if the AOFAS-AH scores were artificially altered, representing the effect of a systematic researcher bias. Materials and Methods: Articles from January 2012 and February 2015 in three orthopaedic journals were queried for use of the AOFAS-AH. Quantities of 4, 8, or 12 points were added to or subtracted from mean AOFAS-AH scores for each study while otherwise maintaining the reported standard deviation to simulate a researcher bias when scoring the subjective sections. Statistical analysis was performed with the adjusted AOFAS-AH mean scores in order to elucidate a potential “reversal” in statistical significance and conclusion. Results: A 1582 original research articles were published during this time period. 128 articles utilized the AOFAS-AH score. 30 articles (23.4%) reported the required statistical data to permit manipulation of AOFAS-AH scores. Nine of the 30 articles (30%) had a reversal following a manipulation of 12 or fewer points. Seven (5.5%) reported the blinding status of the researchers. Conclusion: The potential for bias is high with the AOFAS-AH and its continued is questionable. Researchers utilizing the AOFAS-AH should at a minimum appropriately blind study staff and consider pre-study clarification of subjective terminology. Levels of Evidence: Level IV

Overtightening of the Syndesmosis Revisited and the Effect of Syndesmotic Malreduction on Ankle Dorsiflexion

Category: Ankle, Trauma Introduction/Purpose: Ankle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws. The purposes of the current investigation are: To assess the effect of syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of ankle dorsiflexion. To assess the effect of anterior & posterior syndesmotic malreduction after syndesmotic screw fixation on ankle dorsiflexion. Methods: Fifteen cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro- sensor system after application of a consistent load in the intact state, after compression fixation with a syndesmotic screw and after anterior & posterior malreduction of the syndesmosis. Results: Following screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7±0.87% (mean ± standard error) of baseline ankle ROM. Anterior and posterior displacement of the syndesmosis resulted in dorsiflexion ROM that was 99.1±1.75% and 98.6±1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value =0.88). Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value= 0.99). Conclusion: Maximal dorsiflexion of the ankle is not required prior to syndesmotic fixation. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation has no effect on ankle dorsiflexion thus poor patient outcomes after syndesmotic malreduction does not appear to be the result of loss of dorsiflexion due to mechanical block.