Antibody surface mobility amplifies FcγR signaling via Arp2/3 during phagocytosis.

We report herein that the anti-CD20 therapeutic antibody, rituximab, is rearranged into microclusters within the phagocytic synapse by macrophage Fcγ receptors (FcγR) during antibody-dependent cellular phagocytosis. These microclusters were observed to potently recruit Syk and to undergo rearrangements that were limited by the cytoskeleton of the target cell, with depolymerization of target-cell actin filaments leading to modest increases in phagocytic efficiency. Total internal reflection fluorescence analysis revealed that FcγR total phosphorylation, Syk phosphorylation, and Syk recruitment were enhanced when IgG-FcγR microclustering was enabled on fluid bilayers relative to immobile bilayers in a process that required Arp2/3. We conclude that on fluid surfaces, IgG-FcγR microclustering promotes signaling through Syk that is amplified by Arp2/3-driven actin rearrangements. Thus, the surface mobility of antigens bound by IgG shapes the signaling of FcγR with an unrecognized complexity beyond the zipper and trigger models of phagocytosis.

Midfoot Trauma: Let's Get It Right the First Time.

Lisfranc injuries represent a wide variety of injury patterns, from stable midfoot sprains to grossly displaced fractures and fracture-dislocations. Obtaining and maintaining an anatomic reduction is critical in the treatment of these injuries. Considerable controversy remains as to the optimal method of treatment. Beyond the type and severity of the injury pattern, treatment decisions may ultimately be defined by activity-specific criteria and patient demographics.

Midterm Outcomes of the INBONETM II Total Ankle Arthroplasty.

As the number of total ankle arthroplasties (TAA) performed continues to increase, understanding midterm outcomes can guide both implant selection and preoperative patient counseling. The purpose of this study was to investigate midterm results including the survival rate and reasons for revision for the INBONETM II TAA. Patients undergoing a primary TAA with the study implant and minimum of 4.6 years postoperative follow-up were reviewed from a prospectively collected database. The primary outcome was implant survival. Secondary outcomes included coronal plane radiographic alignment, evaluation for cysts and osteolysis, and failure mode when applicable. Patients were eligible for inclusion in this study if they had a minimum of 4.6-year follow-up TAA with the study implant. Eighty-five TAAs in 83 patients were eligible for inclusion; 75 TAA in 73 patients were included in the study. The mean duration of follow up was 6.2 ± 0.9 years (range 4.7-8.1 years). Thirty-six percent of the TAAs had a preoperative coronal plane deformity of at least 10°, and 12% of the TAAs had at least 20°. There were 6 (8%) implant failures that occurred at a mean 2.0 ± 1.4 years postoperatively. Eighty-one percent of the TAAs had no reoperation events in the follow-up period. Midterm outcomes at a minimum of 4.6 years postoperatively in patients undergoing a TAA using this implant demonstrates acceptable implant survival, an approximately 20% reoperation rate, and maintenance of coronal plane alignment.

Heterotopic Ossification in Total Ankle Arthroplasty: Case Series and Systematic Review.

Heterotopic ossification after total ankle arthroplasty (TAA) is a known sequela and has been reported to contribute to reduced range of motion and poor functional outcomes. However, conflicting results have been reported in the literature. The present study documents the incidence of heterotopic ossification for a novel fourth-generation fixed-bearing 2-component prosthesis and reports a systematic review of the literature. We reviewed the incidence and functional outcome of consecutively enrolled patients who underwent primary Infinity TAA between 2013 and 2015 in a prospective observational study. Preoperative and postoperative radiographic and functional outcome data were collected. A systematic review was also conducted investigating all published studies between 1998 and 2018 reporting the incidence of heterotopic ossification after TAA. The incidence of heterotopic ossification was 70.5% in the 61 patients who underwent primary TAA in the case series. There was no association between heterotopic ossification and American Orthopaedic Foot and Ankle Society (AOFAS) score, foot function index (FFI), visual analogue scale (VAS), and ankle osteoarthritis scale (AOS). Sixteen studies on 1339 TAA implants were included. The overall incidence of heterotopic ossification after TAA was 66.0% at average 3.6 years (range 22.2% to 100%). Four studies (299 ankles) did not address functional outcomes. Eleven studies (960 ankles) reported no association between heterotopic ossification and functional outcomes. One study (80 ankles) reported a statistically significant difference in range of motion (7°) and AOFAS score (7 points). In conclusion, although the incidence of heterotopic ossification after TAA is considerable, there is insufficient literature to suggest that heterotopic ossification after TAA impacts range of motion or functional outcome.

Effects of Cryopreserved Amniotic Membrane-Umbilical Cord Allograft on Total Ankle Arthroplasty Wound Healing.

Relatively high rates of wound healing complications continue to be reported with a total ankle arthroplasty (TAA) anterior incision. The amniotic membrane-umbilical cord (AM-UC) allograft is a regenerative orthobiologic adjunct that modulates wound healing by down-regulating inflammation, enhancing local healing and antimicrobial factors, and reducing scar formation. The purpose of this study was to determine whether local application of a cryopreserved AM-UC allograft enhances soft tissue healing after TAA. A total of 104 patients with symptomatic ankle arthritis who failed conservative management underwent standard TAA. At skin closure, patients were allocated to either the treatment (local application of AM-UC) or control (no allograft) group. Demographic data, patient comorbidities, and radiographic findings were collected. The primary outcome was a major complication necessitating reoperation. Secondary outcomes were time to healing, minor complications (i.e., skin dehiscence, local wound care, use of antibiotics), and patient scar assessment. Local application of an AM-UC allograft significantly decreased the overall time to skin healing (28.5 days vs 40 days; p = .03). Two patients required a reoperation for soft tissue wound complications, with no difference (p = 1.00) between the groups. No statistically significant difference was detected in terms of skin dehiscence, local wound care, or antibiotic prescriptions in the 2 groups. Regenerative technology using local application of a cryopreserved AM-UC allograft may enhance TAA outcomes by decreasing the time to healing. Larger randomized controlled trials are needed to determine whether an AM-UC allograft enhances soft tissue wound healing and ultimately reduces the incidence of devastating soft tissue complications.

Diffusion tensor imaging using multiple coils for mouse brain connectomics.

The correlation between brain connectivity and psychiatric or neurological diseases has intensified efforts to develop brain connectivity mapping techniques on mouse models of human disease. The neural architecture of mouse brain specimens can be shown non-destructively and three-dimensionally by diffusion tensor imaging, which enables tractography, the establishment of a connectivity matrix and connectomics. However, experiments on cohorts of animals can be prohibitively long. To improve throughput in a 7-T preclinical scanner, we present a novel two-coil system in which each coil is shielded, placed off-isocenter along the axis of the magnet and connected to a receiver circuit of the scanner. Preservation of the quality factor of each coil is essential to signal-to-noise ratio (SNR) performance and throughput, because mouse brain specimen imaging at 7 T takes place in the coil-dominated noise regime. In that regime, we show a shielding configuration causing no SNR degradation in the two-coil system. To acquire data from several coils simultaneously, the coils are placed in the magnet bore, around the isocenter, in which gradient field distortions can bias diffusion tensor imaging metrics, affect tractography and contaminate measurements of the connectivity matrix. We quantified the experimental alterations in fractional anisotropy and eigenvector direction occurring in each coil. We showed that, when the coils were placed 12 mm away from the isocenter, measurements of the brain connectivity matrix appeared to be minimally altered by gradient field distortions. Simultaneous measurements on two mouse brain specimens demonstrated a full doubling of the diffusion tensor imaging throughput in practice. Each coil produced images devoid of shading or artifact. To further improve the throughput of mouse brain connectomics, we suggested a future expansion of the system to four coils. To better understand acceptable trade-offs between imaging throughput and connectivity matrix integrity, studies may seek to clarify how measurement variability, post-processing techniques and biological variability impact mouse brain connectomics.

Lisfranc Injuries in the Elite Athlete.

The management of sports-related Lisfranc injuries is optimized by a detailed understanding of the relevant anatomy, mechanisms of injury, clinical diagnostic maneuvers, imaging, and treatment options for patients with this disabling injury. A lower energy ligamentous variant Lisfranc injury, which was first observed in professional football players, has recently been described. The treatment options for patients with a Lisfranc injury include nonsurgical management, open reduction and internal fixation, suture-button fixation techniques, and arthrodesis.

Advances in Surgical Management of Intra-articular Calcaneus Fractures.

Intra-articular calcaneus fractures are commonly sustained after high-energy trauma, and a variety of techniques exists for anatomic reduction and surgical fixation. Traditional approaches using an extended L-shaped lateral incision with lateral plating for open reduction and internal fixation have relatively high complication rates. Common complications include hematoma formation, skin edge necrosis, wound breakdown, and superficial or deep infection. As a result, less invasive techniques have been developed in recent years, including limited-incision sinus tarsi open reduction and internal fixation, percutaneous fixation, and arthroscopic-assisted fixation. These techniques are associated with lower complication rates and equivalent clinical and radiographic outcomes in certain fracture patterns and patient populations.

Mini-open repair of achilles rupture in the national football league.

Tears of the Achilles tendon in professional athletes are an infrequent yet devastating injury. Historical studies have demonstrated not only a poor rate of return to competitive play but have also noted significant declines in performance for those able to return. While classic treatment of these injuries in the competitive athlete has been an open, locked suture repair, this article reports on a consecutive series of professional football athletes who underwent mini-open repair. All athletes returned to professional football, with seven out of nine (78%) returning to National Football League (NFL) competition. Average return to play was 273 days (8.9 months), with one athlete returning at 166 days (5.4 months). There have been no reruptures and no sural nerve or wound healing complications. Although limited in number currently, mini-open repair in NFL athletes has allowed successful return to competitive play with no reruptures and a trend toward faster return to play compared with historical open repair outcomes.

Distal Tibiofibular Syndesmosis Injuries in the National Football League (NFL): A Spectrum of Pathology That Correlates With Time to Return to Full Participation.

BACKGROUND: Studies routinely evaluate high ankle sprains in isolation, but recent data suggest that these injuries are often associated with concomitant pathology, potentially influencing return to full participation. HYPOTHESIS: In National Football League (NFL) players, isolated high ankle sprains are rare and syndesmosis injuries with concomitant pathology will result in increased time to return to full participation. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Distal tibiofibular syndesmosis injuries sustained by NFL players between 2017 and 2019 were identified through NFL Injury Surveillance Database queries and verified with video analysis. Each injury underwent a comprehensive magnetic resonance imaging (MRI) review. Regression modeling was utilized to explore the influence of numerous imaging findings on time to return to full participation. RESULTS: There were 83 external rotation ankle injuries involving the syndesmosis. Isolated distal tibiofibular syndesmosis injuries were rare (n = 11; 13%) and more often associated with other ligamentous injury (deltoid ligament and lateral ligamentous complex) and/or fractures. Regression modeling resulted in clustering of 3 injury pattern groups for time to return to full participation across numerous imaging findings: syndesmosis injury-fracture combinations (250 days [interquartile range [IQR,] 142-266 days]), syndesmosis injury with complete deep deltoid tear or acute diastasis (175 days [IQR, 20-248 days]), and all other syndesmosis injuries (27 days [IQR, 18-46 days]). CONCLUSION: In NFL athletes with external rotation ankle injuries, isolated distal tibiofibular syndesmosis injuries were rare and more often associated with concomitant pathology. Time to return to full participation was affected by an associated fracture and complete deep deltoid ligament tear or diastasis but no other relevant MRI variables such as lateral ligament complex involvement or the presence of osteochondral lesions or bone contusions.

Minimally invasive technique versus an extensile lateral approach for intra-articular calcaneal fractures.

BACKGROUND: The optimal method for treating intra-articular fractures of the calcaneus remains controversial. Extensile approaches allow excellent fracture exposure, but high rates of wound complications are seen. Newer minimally invasive techniques for calcaneus fracture fixation offer a potentially lower wound complication rate, but long-term clinical results are not available. The aim of this study was to compare the outcomes of intra-articular calcaneus fractures treated with open reduction and internal fixation via an extensile approach versus those with a minimally invasive sinus tarsi approach. METHODS: We performed a retrospective review of all intra-articular calcaneal fractures treated operatively between October 2005 and December 2008. A total of 112 fractures were found that met our inclusion criteria; 79 were treated with an extensile lateral approach and 33 via a minimally invasive approach based on surgeon preference. Chart and radiographic results were thoroughly reviewed on all 112 fractures, specifically for wound healing complications and the need for further surgeries within the study period. Additionally, all patients were contacted and asked to return for a research visit that included radiography, clinical examination, and quality of life questionnaires (Short Form 36 [SF-36], foot function index [FFI], visual analog scale [VAS] pain). A total of 47 of 112 (42%) patients returned for a research visit (31 extensile, 16 minimally invasive). RESULTS: The 2 groups were comparable with regard to demographics (age, follow-up, male to female ratio, tobacco use, diabetes, workers' compensation status). In the extensile group, 53% of fractures were Sanders II and 47% were Sanders III, whereas in the minimally invasive group 61% were Sanders II and 39% were Sanders III. The overall wound complication rate was 29% in the extensile group (9% required operative intervention) versus 6% in the minimally invasive group (P = .005) (none required operative intervention). Overall, 20% of the extensile group required a secondary surgery within the study period versus 2% in the minimally invasive group (P = .007). In the group of patients who returned for research visits, the average FFI total score was 31 in the extensile group versus 22 in the minimally invasive group (P = .21). The average VAS pain score with activity was 36 in the extensile group versus 31 in the minimally invasive group (P = .48). Overall, 84% of patients in the extensile group were satisfied with their result versus 94% in the minimally invasive group (P = .32). Both groups had 100% union rates, and no differences were noted in the final postoperative Bohler's angle and angle of Gissane. CONCLUSION: Clinical results were similar between calcaneal fractures treated with an extensile approach and those treated with a minimally invasive approach. However, the minimally invasive approach had a significantly lower incidence of wound complications and secondary surgeries. The minimally invasive approach was a valuable method for the treatment of intra-articular calcaneal fractures, with low complication rates and results comparable to those treated with an extensile approach. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.

Alterations in gait initiation are present in those with posttraumatic ankle osteoarthritis: a pilot study.

The purpose of this investigation was to determine if stereotypical patterns of gait initiation are altered in those with posttraumatic ankle osteoarthritis. Ten subjects, five with unilateral ankle osteoarthritis and five uninjured controls, participated. Subjects completed the SF-36 and Ankle Osteoarthritis Scale to quantify self-reported disability as well as 10 dual-limb static stance trials and 10 gait initiation trials with each leg. Center of pressure outcomes were calculated for static balance trials while the peak center of pressure excursions were calculated for each phase of gait initiation. The results indicate greater self-reported disability (P < .05) and worse static postural control (P < .05) in the ankle osteoarthritis group. Nonstereotypical patterns were also observed during the first and third phases of gait initiation in those with ankle osteoarthritis. The results of this pilot study suggest that supraspinal motor control mechanisms may have changed in those with posttraumatic ankle osteoarthritis.

Are Prospective Criteria or Objective Clinical Measures Utilized in Return to Play (RTP) Decision Making After Ankle Surgery? A Scoping Review.

Background: Manuscripts discussing return to play (RTP) following ankle surgery are common. However, the definition for RTP and the method by which it is determined remains unclear. The purpose of this scoping review was to clarify how RTP is defined following ankle surgery in physically active patients, to identify key factors informing RTP decision making (such as objective clinical measures), and make recommendations for future research. Methods: A scoping literature review was performed in April 2021 using PubMed, EMBASE, and Nursing and Allied Health databases. Thirty studies met inclusion criteria: original research following ankle surgery reporting at least 1 objective clinical test and documentation of RTP. Data were extracted for study methods and outcomes (RTP definition, RTP outcomes, and objective clinical tests). Results: The scoping review found studies on 5 ankle pathologies: Achilles tendon rupture, chronic lateral ankle instability, anterior ankle impingement, peroneal tendon dislocation, and ankle fracture. RTP criteria were not provided in the majority of studies (18/30 studies). In the studies that provided them, the RTP criteria were primarily based on time postsurgery (8/12) rather than validated criteria. Objective clinical outcome measures and patient-reported outcome measures (PROMs) were documented for each surgery when available. Both clinical outcomes and PROMs were typically measured >1 year postsurgery. Conclusion: In physically active patients who have had ankle surgery, RTP remains largely undefined and is not consistently based on prospective objective criteria nor PROMS. We recommend standardization of RTP terminology, adoption of prospective criteria for both clinical measures and PROMs to guide RTP decision making, and enhanced reporting of patient data at the time of RTP to develop normative values and determine when the decision to RTP is not safe. Level of Evidence: Level IV, scoping review.

Etiology and biomechanics of first metatarsophalangeal joint sprains (turf toe) in athletes.

Sprains of the first metatarsophalangeal (MTP) joint, referred to colloquially as "turf toe," are a debilitating sports injury because the hallux is pivotal to an athletes' ability to accelerate and cut. Severe sprains may require weeks to full recovery, and injuries requiring surgery may prevent an athlete from full athletic participation for months. Whereas the diagnosis and treatment of turf toe are well documented in the literature, less is known about the biomechanics of this joint and the mechanical properties of the structures that compose it. Nevertheless, this information is vital to those, such as equipment designers, who attempt to develop athletic footwear and surfaces intended to reduce the likelihood of injury. To that end, this review summarizes the literature on the anatomy of the first MTP joint, on biomechanical studies of the first MTP joint, and on the incidence, mechanisms, and treatment of turf toe. Furthermore, gaps in the literature are identified and opportunities for future research are discussed. Only through a thorough synthesis of the anatomic, biomechanical, and clinical knowledge regarding first MTP joint sprains can appropriate countermeasures be designed to reduce the prevalence and severity of these injuries.

Biplanar proximal phalanx closing wedge osteotomy for hallux rigidus.

BACKGROUND: Many procedures have been described for surgical treatment of symptomatic hallux rigidus. Dorsal cheilectomy of the metatarsophalangeal joint combined with a dorsal-based closing wedge osteotomy of the proximal phalanx (i.e., Moberg procedure) has been described as an effective procedure. For patients with hallux rigidus and clinically significant hallux valgus interphalangeus, the authors previously described a dorsal cheilectomy combined with a biplanar closing wedge osteotomy of the proximal phalanx, combining a Moberg osteotomy with an Akin osteotomy. The purpose of this study was to describe the clinical results of this procedure. METHODS: This article is a retrospective review of prospectively gathered data that reports the clinical and radiographic results of dorsal cheilectomy combined with a biplanar oblique closing wedge proximal phalanx osteotomy (i.e., Moberg-Akin procedure) for patients with symptomatic hallux rigidus and hallux valgus interphalangeus. Consecutive patients were followed and evaluated for clinical and radiographic healing, satisfaction, and ultimate need for additional procedure(s). Thirty-five feet in 34 patients underwent the procedure. RESULTS: All osteotomies healed. At an average of 22.5 months of follow-up, 90% of patients reported good or excellent results, with pain relief, improved function, and fewer shoe wear limitations following this procedure. Hallux valgus and hallux interphalangeal angles were radiographically improved. Other than one patient who requested hardware removal, no patients required additional surgical procedures. CONCLUSIONS: Dorsal cheilectomy combined with a Moberg-Akin procedure was an effective and durable procedure with minimal morbidity in patients with hallux rigidus combined with hallux valgus interphalangeus.

Fifth Metatarsal Jones Fractures: Diagnosis and Treatment.

A Jones fracture, located at the metaphyseal-diaphyseal junction of the fifth metatarsal, is at an increased risk for nonunion and continued pain. Even with excellent surgical technique and postoperative management, a delayed union and refracture can occur. These complications in athletes can have deleterious effects on performance and delay return to sport. This article reviews the classification, diagnosis, and treatment considerations for Jones fractures. Treatment options including nonsurgical management, intramedullary screw, and plate fixation will be covered. The authors preferred technique using intramedullary screw fixation will be discussed in depth. Emerging considerations including biologic augmentation, primary bone grafting, and refracture will be examined as well. Ideal rehabilitation protocols, orthoses, and shoe wear suggestions will be given to optimize patient outcomes.

Foot and Ankle Injections in Athletes.

CONTEXT: Injections are commonly used by health care practitioners to treat foot and ankle injuries in athletes despite ongoing questions regarding efficacy and safety. EVIDENCE ACQUISITION: An extensive literature review was performed through MEDLINE, Google Scholar, and EBSCOhost from database inception to 2021. Keywords searched were injections, athletes, sports, foot and ankle, corticosteroids, platelet-rich plasma, and placental tissue. Search results included articles written in the English language and encompassed reviews, case series, empirical studies, and basic science articles. STUDY DESIGN: Clinical review. LEVEL OF EVIDENCE: Level 4. RESULTS: Corticosteroids, platelet-rich plasma/autologous blood, anesthetic, and placental tissue injections are commonly used in the treatment of foot and ankle injuries. Primary indications for injections in athletes include plantar fasciitis, Achilles tendinosis, isolated syndesmotic injury, and ankle impingement with varying clinical results. CONCLUSIONS: Despite promising results from limited case series and comparative studies, the data for safety and efficacy of injections for foot and ankle injuries in athletes remain inconclusive.

Complications, Reoperations, and Patient-Reported Outcomes Following a 2-Stage Revision Total Ankle Arthroplasty for Chronic Periprosthetic Joint Infections.

BACKGROUND: As total ankle arthroplasty (TAA) becomes more common, chronic periprosthetic joint infections (PJIs) will be encountered more frequently. No studies have reported on patient-reported outcomes following a 2-stage revision procedure for a chronic PJI after a TAA. The primary purpose of this study was to investigate postoperative clinical outcomes at a minimum of 2 years following a 2-stage revision TAA for chronic PJI. METHODS: Patients who underwent a 2-stage revision TAA for a chronic PJI (>4 weeks after a primary TAA) between January 2010 and December 2019 were eligible to be included in this study. Chronic PJI was defined as a sinus tract that directly communicated with the prosthesis or the same organism identified in ≥2 synovial fluid samples. Twelve patients were eligible to be included in this case series. One patient died prior to 2-year follow-up, which left 11 patients available for analysis. All 11 patients underwent reimplantation. The data were found not to be normally distributed; therefore, medians and interquartile ranges (IQRs) were reported. RESULTS: At a median of 3.0 years (IQR 2.0-4.0 years) following the second stage of their revision arthroplasty, the median Foot and Ankle Ability Measure (FAAM) Activities of Daily Living and Sports scores were 60.7 (IQR 52.4, 79.8) and 31.3 (IQR 9.4, 40.6), respectively. At final follow-up, 10 patients (90.9%) were ambulating with a TAA in place. Seven patients (63.6%) required a reoperation including 1 patient who underwent a below-knee amputation. CONCLUSION: Our study suggests that a 2-stage revision TAA may be an option for patients with a chronic PJI. However, patients who undergo a 2-stage revision TAA for a chronic PJI have lower than previously published 2-year FAAM scores and a high rate of reoperation. LEVEL OF EVIDENCE: Level IV, case series.

Management of calcaneal malunion.

The potential for disabling malunion following calcaneal fracture is high, regardless whether a patient is treated nonsurgically or surgically. Fracture displacement typically results in loss of hindfoot height, varus heel position, and widening of the hindfoot, with possible subfibular impingement and irritation of the peroneal tendon and/or sural nerve. Frequently, the subtalar joint develops posttraumatic arthritis. In symptomatic patients with calcaneal malunion, systematic evaluation is required to determine the source of pain. Nonsurgical treatment, such as activity modification, bracing, orthoses, and injection, is effective in many patients. Surgical treatment may involve simple ostectomy, subtalar arthrodesis with or without distraction, or corrective calcaneal osteotomy. A high rate of successful arthrodesis and of patient satisfaction has been reported with surgical management.