Posterior Facet Of Subtalar Joint Research Articles

Three-Dimensional Distance and Coverage Maps in the Assessment of Peritalar Subluxation in Progressive Collapsing Foot Deformity

Category:Ankle; Basic Sciences/Biologics; Hindfoot; OtherIntroduction/Purpose:Progressive collapsing foot deformity (PCFD), formerly termed Adult-Acquired Flatfoot Deformity (AAFD), is a complex 3-dimensional (3D) deformity characterized by peritalar subluxation (PTS) of the hindfoot through the triple joint complex. PTS severity is typically measured at the posterior facet of te subtalar joint, but recent studies have called this into question and presented the middle facet as a more accurate marker of deformity. The objective of this study was to use 3D distance mapping (DM) from weightbearing computed tomography (WBCT) images to assess PTS in PCFD patients and controls across the entire peritalar suface. We hypothesized that 3D DMs would identify the middle facet as a superior marker for PTS, as well as indicate increased extra-articular sinus tarsi and subfibular inpingements in PCFD patients.Methods:In this case control study, we analyzed WBCT data of 20 consecutive patients with flexible PCFD and 10 controls. Novel 3D distance mapping (DM) technique was used to objectively characterize joint coverage across the entire peritalar surface, including both articular (anterior, middle and posterior facets of the subtalar joint) and nonarticular regions (sisus tarsi and subfibular areas). Distance maps were measured in millimeters, and colored to highlight regions of interest. Distances from 1-4mm were shown in blue to indicate expected joint interaction/extra-articular proximity, while distances under 1mm were highlighted in yellow/red indicating close bone proximity consistent with joint space narrowing (articular) or impingement (extra-articular). Joint coverage was defined as percentage of articular area with DMs <4 mm. Coverage Maps (CM) were built highlighting areas of adequate joint interaction (blue), joint subluxation (pink), and impingement (red). Comparisons were performed with independent t-tests or Wilcoxon tests. P values <.05 were considered significant.Results:Overall, coverage was decreased in articular regions and impingement was increased in nonarticular regions of PCFD patients. Objectively, a significant 46.6% average increase in the uncoverage of the middle facet of the subtalar joint was observed in PCFD patients (p<.001), consistent with signifcant middle facet subluxation when compared to controls. No significant similar uncoverage was identified in the anterior or posterior facets. Extra-articularly, an overall 98% increase in sinus tarsi coverage was identified in PCFD patients (p<.007) with direct sinus tarsi impingement in 6 of 20 patients with PCFD, and one of the controls. Direct subfibular impingement was noted in only 1 of 20 PCFD patients, but subfibular space narrowing greater than 2 standard deviations was noted in 17 of 20 PCFD patients. Attached figures demonstrate examples of distance and coverage maps, as well as a comparative averaged assessment of peritalar surface coverage in PCFD and controls.Conclusion:Our study results revealed that when compared to controls PCFD patients demonstrated that a significant decrease in 3D measures of subtalar joint coverage was only identified in the middle facet, but not at the anterior or posterior facets. We also determined significantly decreased inter-bone distances in the sinus tarsi and subfibular regions of PCFD patients, confirming the occurrence of extra-articular impingement in those areas. We hope that the use of these 3D accurate and objective measures of distance (DM) and coverage maps (CM) of middle facet subluxation will support early detection of PCFD patients at high risk for progressive collapse.

3D imaging added value in the treatment and diagnosis of displaced intra-articular calcaneal fractures (DIACF): measuring the orientation of the posterior talo-calcaneal facet in the space

Purpose Measure the reduction quality of calcaneal fractures on 3 D segmented images. Methods The Ethics Review Board approved this study and written informed consent was collected from all patients. Bilateral CT scans of fifty-four patients with unilateral displaced calcaneal fracture were obtained before and after osteosynthesis. Orientation angle of the posterior subtalar joint facet (PTC) of displaced intra-articular calcaneal fractures of 54 patients was measured on segmented 3 D images before and after surgery and compared to the uninjured side. This orientation angle (OAC) is the average of every normal vector of each point of the PTC, as compared to the main calcaneal axis (calculated by first principal component analysis). The PTC is a well-known anatomical structure, relatively easy to identify on 3 D imaging. Results This OAC angle was low before surgery (mean= 95°, std dev= 6°), statistically significantly different from the uninjured side value, p < 0.001. The OAC angle of the operated bone was nearly equal to the uninjured side (mean= 103°, std dev= 5°), without any statistically significant difference between postoperative values and uninjured side values. We found linear correlation between the quality of the reduction when assessed with this OAC and the functional score (AOFAS) (Adjusted R2=0.62, p = 0.04). Conclusions This angle seems to be useful to quantify the quality of the operative reduction of displaced intra-articular calcaneal fractures.

Functional outcome of subtalar arthrodesis in posttraumatic arthritis

Introduction: Involvement of the subtalar joint in fracture calcaneus malunion may give rise to chronic pain and permanent functional impairment. This study evaluated the functional result of subtalar joint fusion and effectiveness of a technique using double lag screw from the posteromedial calcaneus to the talus. Materials and Methods: In between April 2015 and April 2017, we performed 12 isolated subtalar arthrodeses by double lag screw technique from posteroinferior calcaneus to talus. The average patient age was 39 (range 28–50) years. There were 9 males and 3 females. Results: Eleven out of 12 joints were fused except one who developed infection, resulting in an overall fusion rate of above 91%. The average time for fusion was 4.5 months (ranging from 3 to 6 months). There was no correlation between the type of accident, the weight of the patient, and the recovery period. Conclusion: Using the double lag screws of 6.5 mm across the posterior facet of subtalar joint resulted in fusion of joint in above 91% of patients. The relief from pain was obtained in 100% of cases. This is a simple and reliable technique for achieving fusion of the subtalar joint.

Functional outcome of subtalar arthrodesis using double lag screw technique

Background: This study evaluated the functional result of subtalar joint fusion and effectiveness of a technique using double lag screw from posteroinferior calcaneus to talus in post traumatic subtalar arthritis following the calcaneal intra-articular fracture. Materials and Methods: In between January 2012 and August 2013, we performed 10 isolated subtalar arthrodesis by double lag screw technique from posteroinferior calcaneus to talus, across posterior facet of subtalar joint, after denuding the joint cartilage, combined with application of an autograft taken from iliac crest, by open method. The average patient age was 47 (range 35-60) year. There were 7 male and 3 female. The indication was the pain following the post-traumatic arthritis of subtalar joint in intra-articular fracture of posterior facet of calcaneus. Result: All 10 joints were fused except one who undergone delayed fusion because of infection, resulting in an overall fusion rate of above 90%. The average time to fusion was 12.3+/−3.4 weeks. The fixation screw was removed in 2/10 joint at an average of 8.8+/−0.5 month. Conclusion: Using the double lag screws of 6.5mm across the posterior facet of subtalar joint resulted in fusion of joint in above 90% of patients. The relief from pain was obtained in 100% of cases. This is a simple and reliable technique for achieving fusion of subtalar joint.

Measurement of Mid-Calcaneal Length on Plain Radiographs

The authors present a new method to reliably measure the length of the mid-portion of the calcaneus. The authors defined the "mid-calcaneal length" as the line connecting the high point of the convex arc of the posterior subtalar joint facet and the low point of the concave arc of the calcaneocuboid joint. Statistical analysis of 810 measurements taken by 6 observers confirmed high intraobserver reliability, interobserver reliability, and internal consistency (Cronbach coefficient α = .98) and low error rate (Pearson correlation coefficient = .0001). The authors have used this measurement as a tool to determine the change in calcaneal length after osteotomy lengthening procedures and present it as a tool for clinical practice and research.