Talal A. Zahoor

Outcomes After Interpositional Arthroplasty of the First Metatarsophalangeal Joint

Background: For patients with hallux rigidus seeking a motion-sparing procedure, interposition arthroplasty is an alternative to fusion. The purpose of this study was to report patient outcomes after interpositional arthroplasty for hallux rigidus. Methods: All patients undergoing interpositional arthroplasty at our institution from 2001 to 2014 were identified and a retrospective chart review was performed. Follow-up was conducted through a telephone survey to obtain survivorship, satisfaction, and functional scores. Survivorship of the interpositional arthroplasty procedure was defined as no subsequent surgery on the hallux after the index procedure. Patients were excluded for incomplete records. Complications were recorded. From 2001 to 2014, 183 patients were identified. Of these, 14 were excluded for incomplete data, leaving 169 patients. Of these, 133 had an average follow-up of 62.2 months (range, 24.3 months to 151.2 months). Results: The overall failure rate was 3.8% (5/133). Patient-reported outcome was rated as excellent in 65.4% (87/133) or good in 24.1% (32/133) of patients and fair or poor in 10.5% (14/133) of patients. Of 133 patients, 101 (76%) were able to return to fashionable or regular footwear. The infection rate was 1.5% (2/133). Patient-reported cock-up deformity of the first metatarsophalangeal joint (MTPJ) occurred in 4.5% (6/133) of patients. In addition, 17.3% (23/133) of patients reported metatarsalgia of the second or third MTPJ at the time of final follow-up, and there was no significant difference between interposition types (P = .441). Conclusion: Interpositional arthroplasty for hallux rigidus was found to have excellent or good results in most patients at a mean follow-up of 62.2 months. Level of Evidence: Level IV, retrospective case series.

Influence of Bone and Muscle Injuries on the Osteogenic Potential of Muscle Progenitors: Contribution of Tissue Environment to Heterotopic Ossification

By using surgical mouse models, this study investigated how the tissue environment influences the osteogenic potential of muscle progenitors (m‐progenitors) and potentially contributes to heterotopic ossification (HO). Injury was induced by clamping the gluteus maximus and medius (group M) or osteotomy of greater trochanter (group O) on the right hip, as well as combined muscle injury and osteotomy of greater trochanter (group M+O). The gluteus maximus and medius of the operated hips were harvested at days 1, 3, 5, and 10 for isolation of m‐progenitors. The cells were cultured in an osteogenic medium for 3 weeks, and osteogenesis was evaluated by matrix mineralization and the expression of osteogenesis‐related genes. The expression of type I collagen, RUNX2 (runt‐related transcription factor 2), and osteocalcin by the m‐progenitors of group M+O was significantly increased, compared with groups M and O. Osteogenic m‐progenitors in group O increased the expression of bone morphogenetic protein 2 and also bone morphogenetic protein antagonist differential screening‐selected gene aberrative in neuroblastoma. On histology, there was calcium deposition mostly in the muscles of group M+O harvested at day 10. CD56, representing myogenic progenitors, was highly expressed in the m‐progenitors isolated from group M (day 10), but m‐progenitors of group M+O (day 10) exhibited the highest expression of platelet‐derived growth factor receptor α (PDGFR‐α), a marker of muscle‐derived mesenchymal stem cells (M‐MSCs). The expressions of PDGFR‐α and RUNX2 were colocalized in osteogenic m‐progenitors. The data indicate that the tissue environment simulated in the M+O model is a favorable condition for HO formation. Most likely, M‐MSCs, rather than myogenic progenitors, in the m‐progenitors participate in HO formation.

A Surgical Model of Posttraumatic Osteoarthritis With Histological and Gait Validation

Background: Posttraumatic osteoarthritis (PTOA) is secondary to an array of joint injuries. Animal models are useful tools for addressing the uniqueness of PTOA progression in each type of joint injury and developing strategies for PTOA prevention and treatment. Hypothesis: Intra-articular fracture induces PTOA pathology. Study Design: Descriptive laboratory study. Methods: Through a parapatellar incision, the medial tibial plateau was exposed in the left knees of 8 Sprague-Dawley rats. Osteotomy at the midpoint between the tibial crest and the outermost portion of the medial tibial plateau, including the covering articular cartilage, was performed using a surgical blade. The fractured medial tibial plateau was fixed with 2 needles transversely. The fractured knees were not immobilized. Before and after surgery, rat gait was recorded. Rats were sacrificed at week 8, and their knees were harvested for histology. Results: After intra-articular fracture, the affected limbs altered gait from baseline (week 0). In the first 2 weeks, the gait of the operated limbs featured a reduced paw print intensity and stride length but increased maximal contact and stance time. Reduction of maximal and mean print area and duty cycle (the percentage of stance phase in a step) was present from week 1 to week 5. Only print length was reduced in weeks 7 and 8. At week 8, histology of the operated knees demonstrated osteoarthritic pathology. The severity of the PTOA pathology did not correlate with the changes of print length at week 8. Conclusion: Intra-articular fracture of the medial tibial plateau effectively induced PTOA in rat knees. During PTOA development, the injured limbs demonstrated characteristic gait. Clinical Relevance: Intra-articular fracture represents severe joint injury and associates with a high rate of PTOA. This animal model, with histologic and gait validations, can be useful for future studies of PTOA prevention and early diagnosis.

Minimally Invasive Calcaneal Displacement Osteotomy Site Using a Reference Kirschner Wire: A Technique Tip

As a standard open approach, the lateral oblique incision has been widely used for calcaneal displacement osteotomy. However, just as with other orthopedic procedures that use an open approach, complications, including wound healing problems and neurovascular injury in the heel, have been reported. To help avoid these limitations, a percutaneous technique using a Shannon burr for calcaneal displacement osteotomy was introduced. However, relying on a free-hand technique without direct visualization at the osteotomy site has been a major obstacle for this technique. To address this problem, we developed a technical tip using a reference Kirschner wire. A reference Kirschner wire technique provides a reliable and accurate guide for minimally invasive calcaneal displacement osteotomy. Also, the technique should be easy to learn for surgeons new to the procedure.

Effect of Low-Intensity Pulsed Ultrasound on Joint Injury and Post-Traumatic Osteoarthritis: an Animal Study

This study investigated the therapeutic potential of low-intensity pulsed ultrasound (LIPUS) in post-traumatic osteoarthritis (PTOA). Intra-articular fracture of the medial tibial plateau was surgically created in 30 rats. LIPUS was applied to the operated joints either for the first 2 wk (LIPUS1-2 group) or in weeks 4 and 5 after intra-articular fracture (LIPUS4-5 group). In controls, the operated knees were not treated with LIPUS (LIPUS0 group). The rats were monitored with weekly gait analysis and euthanized at week 8. Among the altered gait parameters, the maximal and average paw print areas in the LIPUS1-2 and LIPUS4-5 groups, but not the LIPUS0 group, had either reached baseline or significantly recovered (70%, p <0.05) by week 8. PTOA pathology in both the LIPUS1-2 and LIPUS4-5 groups was less severe than that in the LIPUS0 group (Mankin score: 5.4 and 4.5 vs. 8.8, p <0.05). In conclusion, LIPUS treatment partially improved the gait of the affected limbs and reduced cartilage degeneration in PTOA.

Achilles Tendon Allograft Incorporated with Autologous Mesenchymal Stem Cells: an Animal Model

Category: Basic Sciences/Biologics Introduction/Purpose: Achilles tendinopathy and rupture are common and generally can heal without aggressive intervention. When a large defect of Achilles tendon is left by trauma or severe tendinopathy, however, it is a challenge to restore the function of Achilles tendon, because of the size of the tendon and the limitation in Achilles autograft. In contrast, allograft of Achilles tendon does not have restrain of supply. The biology, biomechanics and function of the transplanted Achilles allograft, however, are unknown. Particularly, the revitalization of Achilles allograft is a concern. Mesenchymal stem cells (MSCs) are known for their capability of multi-lineage differentiation and regenerative potentials. Methods: Achilles allografts were harvested from donor rats (approved by Institutional Animal Care and Usage Committee) and kept at -80ºC before transplantation. Subcutaneous adipose tissue was harvested from the would-be allograft recipient rats for isolation of MSCs. MSCs were culture expanded and characterized. On the day of allograft transplantation, adipose tissue derived MSCs were collected and applied onto allografts (1x105 per allograft). Achilles tendon was resected from the left hind limb of the adipose tissue donor rats. Achilles allograft, with or without autologous MSCs, was implanted and sutured with calf muscles proximately and calcaneus distally. Animal gait was recorded in the week prior to Achilles allograft transplantation (week 0) and every week postoperatively, using a CatWalk system. The transplanted Achilles allografts, with or without MSC incorporation, as well as the normal Achilles tendon in the opposite limbs were harvested at 4 weeks for biomechanical testing and histology. Results: The operated limbs altered gait significantly. By week 4, the recoveries of stand index (speed at which the paw loses contact with ground) and duty cycle (percentage of the stance phase in a step cycle) of the reconstructed limbs were not statistically different between the Achilles allograft group and Achilles allograft+MSCs group. Maximum load of failure among Achilles allograft group (27.2±11.5 N), Achilles allograft+MSCs group (27.6±6.4 N) and normal Achilles tendon group (19.9±9.9 N) was not significantly different. On histology, cellularity was generally higher in Achilles allograft+MSCs group than Achilles allograft group (average cellularity grade 2.7±0.5 vs 1.7±0.5). Type III collagen staining was more intense in the Achilles allograft+MSCs group than in the Achilles allograft group. Conclusion: In this pilot study, the allograft incorporated with autologous MSCs demonstrated no significant differences from Achilles allograft alone in maximum failure load and gait analysis. Supplementation of MSCs increased the cellularity and led to more active matrix remodeling in the allograft but these biological improvements did not translate into rat gait and the strength of the implanted allograft. It may be necessary to follow up the animals for an extended period because the remodeling of Achilles allograft takes longer than 4 weeks. In addition, the small size of the rat Achilles allograft might falsely show an accelerated revitalization.

Outcomes of Iliac Crest Bone Marrow Aspirate Injection for the Treatment of Recalcitrant Non- Insertional Achilles Tendinitis

Category: Sports Introduction/Purpose: Non-insertional Achilles tendinitis is a common cause of posterior ankle and heel pain in active and sedentary patients. Though the majority of patients respond to first-line non-operative management including activity modification, immobilization, orthotics, and physical therapy with tendon stretching, there is no consensus for patients that fail these treatments. We evaluate the role of iliac crest bone marrow aspirate concentrate (BMAC) as a safe and effective treatment option for recalcitrant cases. Methods: A retrospective chart review was conducted of patients with greater than 12 months of non-insertional Achilles tendinitis symptoms despite appropriate conservative treatment. Each patient had BMA harvested from the iliac crest, concentrated by centrifugation, and then injected into the Achilles tendon. Symptoms were assessed using the Visual Analogue Scale (VAS) pain score, collected at the preoperative office visit and at 6 weeks, 12 weeks, and 24 weeks after the procedure. Co- morbidities, concurrent procedures, and complications were also recorded. Results: A total of 21 patients (22 feet) were treated with iliac crest BMA concentrate injections. Preoperatively, the average VAS pain score was 6.8 (SD 2.0). Postoperatively, the average VAS was 4.0 (SD 2.5) at 6 weeks, 2.7 (SD 2.1) at 12 weeks, and 2.2 (SD 2.1) at 24 weeks. At 24 weeks postoperatively, there was a statistically significant decrease VAS score from baseline (p < 0.001), with a mean decrease by 4.6 (SD 3.1). There were no adverse effects reported at the surgical site or donor site morbidity at the iliac crest such as wound infection, hematoma, or persistent pain. Conclusion: Iliac crest BMAC appears to be a safe, effective, and potentially lasting treatment option for patients with intractable, non-insertional Achilles tendinitis. Patients demonstrated a statistically significant decrease in VAS pain score postoperatively with no complications at the donor or injection site.

Interobsever Variability of Measurements for Flatfoot Deformity Using High Resolution Weightbearing Cone-Beam CT Examination According to Reader Experience

Category: Other Introduction/Purpose: To evaluate interobserver reliability among readers of different clinical experience by applying measurements for adult acquired flatfoot deformity (AAFD) using high-resolution three-dimensional (3D) weightbearing (WB) cone-beam CT (CBCT) examination. Methods: In this IRB approved study, 20 patients with flexible AAFD [12 male, 8 female; mean age 54.2 (20-88) years] were scanned with standing (weightbearing) CTs. Two blinded observers, a medical student and a foot/ankle surgeon, applied validated AAFD measurements in sagittal, coronal, and axial planes using predefined anatomical landmarks. Interobserver reliability was calculated using Pearson correlation. Results: There was significant interobserver agreement with high correlation for the following measurements(p < 0.0001): distances between medial cuneiform to-floor (r=0.981) and to-skin (r=0.986), navicular to-floor (0.992) and to-skin (r=0.900); cuboid to-floor (r=0.975) and to-skin (r=0.978), and calcaneus-to-fibula (r=0.808); calcaneal inclination angle (r=0.795); forefoot arch angle (r=0.983); and subtalar horizontal angles at 25%, 50%, and 75% of the anteroposterior joint length (r=0.784, 0.891, 0.809). Significant agreement with moderate correlation was additionally demonstrated for talar-first metatarsal angle (r=0.553, p < 0.014), medial cuneiform-first metatarsal angle (r=0.668, p < 0.001), and navicular-cuneiform angle (r=0.746, p < 0.0002). Level of training did not influence the reliability of any measurements except medial cuneiform-first metatarsal angle (specialist: 8.83°; student: 1.61°; p < 0.01). Statistically insignificant difference between readers (p>0.05) was noted in mean talar-first metatarsal and subtalar horizontal angles. Conclusion: While literature describes large variability for AAFD measurements from plain radiographs among readers of varying medical experience, 3D WB CBCT can yield similar measurements using predefined planes with high reliability, independent of reader experience.

Flexible Adult Acquired Flatfoot Deformity: Comparison Between Weightbearing and Nonweightbearing Cone-Beam CT Examinations

Category: Other Introduction/Purpose: Adult acquired flatfoot deformity (AAFD) is a biomechanical derangement involving the three- dimensional (3D) midfoot and hindfoot osseous complex, which can be challenging to optimally characterize using conventional two-dimensional (2D) plain radiographs. Weightbearing (WB) Cone-Beam CT (CBCT) can better demonstrate the deformity of the 3D structures during WB. Therefore, we compared validated AAFD measurements between non-weightbearing (NWB) and WB CBCT images. Methods: In this prospective, IRB approved study, 20 patients were included, 12 males and 8 females, mean age of 54.21 (20-88) years, with clinical diagnosis of flexible AAFD. Subjects were scanned with standing (WB) and seated (NWB) CBCTs. WB and NWB CBCT images were assessed with traditional flatfoot measurements obtained at sagittal, coronal, and axial planes using predefined anatomical landmarks, by two independent observers. Interobserver reliability was calculated using Pearson correlation. Results: The measurements in patients with AAFD differed significantly between WB and NWB CBCT images. Specifically, WB images showed, when compared to NWB, decreased forefoot arch angle (mean difference: 9.91°, p < 0.0001), increased talus-first metatarsal angle (10.59°, p < 0.0001), increased navicular-medial cuneiform angle (13.89°, p < 0.0001), decreased navicular-floor (coronal 14.05mm/sagittal 14.91mm, p < 0.0001) and navicular-skin distances (coronal 5.87mm/sagittal 8.25mm, p < 0.0001), decreased medial cuneiform-floor (coronal 10.79mm/sagittal 11.07mm, p < 0.0001) and medial cuneiform-skin distances (coronal 4.45mm/sagittal 5.78mm, p < 0.0001), and decreased cuboid-floor (5.78mm, p < 0.0001) and cuboid-skin distances in the sagittal plane (4.60mm, p < 0.0001). Interobserver reliability was good to excellent (0.610-0.991). Conclusion: Traditional adult acquired flatfoot deformity radiographic measurements are obtainable using high resolution 3D WB CBCT imaging, and can help characterize the biomechanical derangements during weightbearing in subjects with flexible AAFD.

Long-Term Outcome Following Interpositional Arthroplasty of the First Metatarsophalangeal Joint

Category: Midfoot/Forefoot Introduction/Purpose: Surgical treatment for osteoarthritis of the first metatarsophalangeal joint (MTPJ) includes cheilectomy or fusion for advanced arthritis. In addition, procedures to preserve or restore motion have demonstrated promising short-term results. Currently, no studies have described long-term results following interpositional arthroplasty. Our institution has performed interpositional arthroplasty with autograft (joint capsule/extensor hallucis brevis) or allograft (dermal matrix) with anecdotal success for over 15 years. The purpose of this study is to report long-term outcomes following interpositional arthroplasty. Methods: All patients undergoing interpositional arthroplasty at our institution from 2000-2015 were identified and a retrospective chart review was performed. Long-term follow-up was conducted through a telephone survey to obtain survivorship, satisfaction, and functional scores. Average follow-up was 89.1 months (range, 6 to 179 months). Survivorship of the interpositional arthroplasty procedure was defined as no subsequent surgery on the hallux after the index procedure. Results: From 2000-2015, 292 interpositional arthroplasties were performed at our institution. The overall failure rate was 1.7 % (5/292), which included patients requiring revision surgery (2 patients) or subsequent fusion (3 patients). Autograft interpositional arthroplasty had a failure rate of 2.1% (2/94) and allograft interposition was 1.5% (3/198). Failure and reoperation occurred at an average of 11 months from the index procedure (range, 6-17 months). 88.7% of patients rated their overall satisfaction as excellent or good. Average preoperative VAS score was 8.2 ± 1.5 (range, 6 to 10) and 2.1 ± 1.6 (range, 0 to 7) at latest follow-up, and (79.1%) patients reported tolerance to fashionable shoes. There were no major wound complications. The most common complications were metatarsalgia (8.6%) and cock-up deformity (5.7%). Conclusion: Interpositional arthroplasty demonstrated excellent long-term survivorship and high patient satisfaction at long-term follow-up.