Incidence, treatment, and outcomes of modern dual-mobility intraprosthetic dissociations.

Aims: Dual-mobility (DM) components are increasingly used to prevent and treat dislocation after total hip arthroplasty (THA). Intraprosthetic dissociation (IPD) is a rare complication of DM that is believed to have decreased with contemporary implants. This study aimed to report incidence, treatment, and outcomes of contemporary DM IPD. Methods: A total of 1,453 DM components were implanted at a single academic institution between January 2010 and December 2021: 695 in primary and 758 in revision THA. Of these, 49 presented with a dislocation of the large DM head and five presented with an IPD. At the time of closed reduction of the large DM dislocation, six additional IPDs occurred. The mean age was 64 years (SD 9.6), 54.5% were female (n = 6), and mean follow-up was 4.2 years (SD 1.8). Of the 11 IPDs, seven had a history of instability, five had abductor insufficiency, four had prior lumbar fusion, and two were conversions for failed fracture management. Results: The incidence of IPD was 0.76%. Of the 11 IPDs, ten were missed either at presentation or after attempted reduction. All ten patients with a missed IPD were discharged with a presumed reduction. The mean time from IPD to surgical treatment was three weeks (0 to 23). One patient died after IPD prior to revision. Of the ten remaining hips with IPD, the DM head was exchanged in two, four underwent acetabular revision with DM exchange, and four were revised to a constrained liner. Of these, five (50%) underwent reoperation at a mean 1.8 years (SD 0.73), including one additional acetabular revision. No patients who underwent initial acetabular revision for IPD treatment required subsequent reoperation. Conclusion: The overall rate of IPD was low at 0.76%. It is essential to identify an IPD on radiographs as the majority were missed at presentation or after iatrogenic dissociation. Surgeons should consider acetabular revision for IPD to allow conversion to a larger DM head, and take care to remove impinging structures that may increase the risk of subsequent failure.

The Frank Stinchfield Award: Assembly and Dissociation Forces Differ Between Commonly Used Dual Mobility Implants: A Biomechanical Study.

BACKGROUND: Intraprosthetic dissociation (IPD) is a complication unique to dual mobility (DM) implants where the outer polyethylene head dissociates from the inner femoral head. Increasing reports of IPD at the time of closed reduction of large head DM dislocations prompted this biomechanical study evaluating the assembly and dissociation forces of DM heads. METHODS: We tested 17 polyethylene DM heads from 5 vendors. Of the heads, 12 were highly cross-linked polyethylene (4 vendors) and 5 were infused with vitamin E (2 vendors). Heads were between 46 and 47 mm in diameter, accepting a 28 mm-inner ceramic head. Implants were assembled and disassembled using a servohydraulic machine that recorded the forces and torques applied during testing. Dissociation was tested via both axial pull-out and lever-out techniques, where lever-out simulated stem-on-acetabular component impingement. RESULTS: The initial maximum assembly force was significantly different between all vendors (P < .01) and decreased for all implants with subsequent assembly. Vendor 4-E (Link with vitamin E) heads required the highest assembly force (1,831.9 ± 81.95 N), followed by Vendor 3 (Smith & Nephew), Vendor 5 (DePuy Synthes), Vendor 1-E (Zimmer Biomet with vitamin E), Vendor 2 (Stryker), and Vendor 1 (Zimmer Biomet Arcom). Vendor 4-E implants showed the greatest dissociation resistance in both pull-out (2,059.89 N, n = 1) and lever-out (38.95 ± 2.79 Nm) tests. Vendor 1-E implants with vitamin E required higher assembly force, dissociation force, and energy than Vendor 1 heads without vitamin E. CONCLUSIONS: There were notable differences in DM assembly and dissociation forces between implants. Diminishing force was required for assembly with each additional trial across vendors. Vendor 4-E DM heads required the highest assembly and dissociation forces. Vitamin E appeared to increase the assembly and dissociation forces. Based on these results, DM polyethylene heads should not be reimplanted after dissociation, and there may be a role for establishing a minimum dissociation energy standard to minimize IPD risk.

Trans-ulnar fracture dislocations of the elbow: a systematic review and clarification of classification systems.

BACKGROUND: Complex elbow dislocations in which the dorsal cortex of the ulna is fractured can be difficult to classify and therefore treat. These have variably been described as either Monteggia variant injuries or trans-olecranon fracture dislocations. Additionally, O'Driscoll et al classified coronoid fractures that exit the dorsal cortex of the ulna as "basal coronoid, subtype 2" fractures. The Mayo classification of trans-ulnar fracture dislocations categorizes these injuries in 3 types according to what the coronoid remains attached to: trans-olecranon fracture dislocations, Monteggia variant fracture dislocations, and trans-ulnar basal coronoid fracture dislocations. The purpose of this study was to evaluate the outcomes of these injury patterns as reported in the literature. Our hypothesis was that trans-ulnar basal coronoid fracture dislocations would have a worse prognosis. MATERIALS AND METHODS: We conducted a systematic review to identify studies with trans-ulnar fracture dislocations that had documentation of associated coronoid injuries. A literature search identified 16 qualifying studies with 296 fractures. Elbows presenting with basal subtype 2 or Regan/Morrey III coronoid fractures and Jupiter IIA and IID injuries were classified as trans-ulnar basal coronoid fractures. Patients with trans-olecranon or Monteggia fractures were classified as such if the coronoid was not fractured or an associated coronoid fracture had been classified as O'Driscoll tip, anteromedial facet, basal subtype I, or Regan Morrey I/II. RESULTS: The 296 fractures reviewed were classified as trans-olecranon in 44 elbows, Monteggia variant in 82 elbows, and trans-ulnar basal coronoid fracture dislocations in 170 elbows. Higher rates of complications and reoperations were reported for trans-ulnar basal coronoid injuries (40%, 25%) compared to trans-olecranon (11%, 18%) and Monteggia variant injuries (25%, 13%). The mean flexion-extension arc for basal coronoid fractures was 106° compared to 117° for Monteggia (P < .01) and 121° for trans-olecranon injuries (P = .02). The mean Mayo Elbow Performance Score was 84 points for trans-ulnar basal coronoid, 91 for Monteggia (P < .01), and 93 for trans-olecranon fracture dislocations (P < .05). Disabilities of the Arm, Shoulder and Hand and American Shoulder and Elbow Surgeons scores were 22 and 80 for trans-ulnar basal coronoid, respectively, compared to 23 and 89 for trans-olecranon fractures. American Shoulder and Elbow Surgeons was not available for any Monteggia injuries, but the mean Disabilities of the Arm, Shoulder and Hand was 13. DISCUSSION: Trans-ulnar basal coronoid fracture dislocations are associated with inferior patient reported outcome measures, decreased range of motion, and increased complication rates compared to trans-olecranon or Monteggia variant fracture dislocations. Further research is needed to determine the most appropriate treatment for this difficult injury pattern.

Dislocated and Dissociated Dual-Mobility Components Are Easily Missed and More Than Half Fail Closed Reduction: Six Tips to Aid Management.

Dual-mobility (DM) implants reduce the risk of dislocation in patients who have undergone total hip arthroplasty (THA); however, DM implants are at risk for large-head dislocation and intraprosthetic dissociation (IPD), where the inner femoral head dissociates from the outer polyethylene head. This study aimed to report the incidence of DM dislocation and IPD, evaluate the rate of recognition of IPD before and after reduction, investigate the outcomes of these complications, and provide treatment recommendations for their management. Methods: Between 2010 and 2021, 695 primary and 758 revision THAs were performed with DM constructs at a single institution. There were 44 large-head dislocations (3.0%) and 10 IPDs (0.7%). Four additional IPDs occurred during attempted closed reduction, increasing the IPD incidence to 0.96%. We reviewed prior instability history, dislocation management, success of reduction, recognition of IPD, and subsequent rates of revision and complications. The mean follow-up was 2.5 years. Results: Nine of 10 IPDs were missed at presentation and thus not treated as such. Sixty-three percent of attempted closed reductions in the emergency department failed and led to 4 IPDs and 1 periprosthetic fracture. Reduction success was associated with the following factors: use of general anesthesia with paralysis (p = 0.02), having the reduction performed by an orthopaedist (p = 0.03), and undergoing only 1 reduction attempt (p = 0.015). Two-thirds of dislocations required revision. The rate of redislocation was 33%, and 5 hips required subsequent revision at a mean of 1.8 years after the initial dislocation. Conclusions: We present an evaluation of DM-implant dislocation and dissociation along with management recommendations based on these data. Given the low success and high complication rates of attempted closed reduction and the need for eventual revision, we recommend that all patients with dislocated DM implants be brought to the operating room for closed reduction as well as potential revision if the reduction fails. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Lack of radiosensitivity predicts poor disease specific survival in myxoid liposarcoma.

BACKGROUND: Compared to other sarcomas, myxoid liposarcoma (ML) is known to be radiosensitive, with improved oncologic outcomes. Although these tumors "shrink" following radiotherapy, there is a paucity of data examining the degree of radiosensitivity and oncologic outcome. The purpose of the study was to evaluate pre- and postradiotherapy tumor volume to determine if size reduction impacts outcome. METHODS: We reviewed 62 patients with ML undergoing surgical resection combined with preoperative radiotherapy, with pre- and postradiotherapy MRI. This included 34 (55%) males, with a mean age of 47 ± 14 years. All tumors were deep to the fascia, and 12 (19%) patients had tumors with a >5% round-cell component. RESULTS: The mean volume reduction was 54% ± 29%. Compared to patients with >25% volume reduction, patients with reduction ≤25% had worse 10-year disease specific survival (86% vs. 37%, p < 0.01), in addition to an increased risk of metastatic disease (HR 4.63, p < 0.01) and death due to disease (HR 4.52, p < 0.01). CONCLUSION: Lack of volume reduction is a risk factor for metastatic disease and subsequent death due to disease in patients with extremity ML treated with combined preoperative radiotherapy and surgery. This data could be used to stratify patients for adjuvant therapies and follow-up intervals.

Surgical Outcomes of Primary Dermatofibrosarcoma Protuberans: A Retrospective, Multicenter Study.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive tumor with a low rate of metastatic disease. Previous series have shown a superiority of Mohs micrographic surgery (MMS) compared with wide local excision (WLE). Likewise, there is paucity of data examining the long-term follow-up of patients. OBJECTIVE: The purpose of the current study was to examine the outcome of surgical treatment of primary DFSP of the trunk and extremities. METHODS: We reviewed 236 patients (115 females, 121 males, mean age 41 ± 15 years) undergoing MMS (n = 81, 34%) or WLE (n = 155, 66%) to treat a primary DFSP. Mean tumor size and follow-up was 4 ± 2 cm and 7 years, respectively. Final margins were negative in 230 (97%) patients. RESULTS: There was no difference (p > 0.05) in patient age, sex, tumor size, negative margin excision, or history of a previous inadvertent excision between patients who underwent WLE and those undergoing MMS. There were two cases of local recurrence and two cases of metastasis, with no difference in the 5-year local recurrence-free survival (98% vs. 99%, p = 0.69) or metastatic-free survival (98% vs. 100%, p= 0.27) between WLE and MMS. CONCLUSION: There was no difference in oncologic outcome comparing MMS with WLE for DFSP outside the head and neck. The goal of treatment for DFSP is to achieve a negative margin, regardless of surgical treatment modalities. A 'less is more' approach to follow-up can likely be taken for patients with completely resected DFSP in easy-to-examine anatomical areas. In these patients, no formal follow-up should be required.

Preoperative Antibiotics Influence Culture Yield in the Treatment of Hand, Wrist, and Forearm Infections.

When treating upper-extremity infections, clinicians frequently must decide whether to initiate antibiotics or delay them with the goal of optimizing culture yield at the time of surgical debridement. The purpose of this study was to determine whether the administration of preoperative antibiotics affects intraoperative culture yield and whether there is a "safe" interval prior to culture acquisition within which antibiotics can be administered without affecting culture yield. Methods: We conducted a retrospective review of 470 consecutive patients who underwent debridement for a presumed acute infection of the hand, wrist, or forearm at a single tertiary care center between January 2015 and May 2020. Data including patient demographics, mechanism of infection and affected body part(s), and details of antibiotic administration, including type and timing with respect to culture acquisition, were collected. Results: Three hundred and forty-one patients (73%) received preoperative antibiotics prior to debridement and culture acquisition. The rate of positive cultures among patients who received preoperative antibiotics was 81% compared with 95% among patients who did not receive preoperative antibiotics (p < 0.01; odds ratio, 4.73). Even a single dose of antibiotics imparted a significantly increased risk of obtaining negative intraoperative cultures, and an incremental increase in the likelihood of obtaining negative cultures was seen with each preoperative dose given up to 7 doses. We did not identify a "safe" interval of time between antibiotic administration and culture acquisition such that culture yield was not affected. Conclusions: Patients who received preoperative antibiotics for the treatment of upper-extremity infections were approximately 5 times more likely to have negative cultures at the time of debridement than those who did not receive preoperative antibiotics. This effect persisted regardless of the number of doses given or the interval between antibiotic administration and culture acquisition. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Long-term Outcome of Acral Ewing Sarcoma.

BACKGROUND/AIM: Ewing sarcoma is a common primary bone tumor, often located in the distal femur or pelvis. Acral Ewing sarcoma of the upper extremity is exceedingly rare. The aim of this study was to review our institution's experience with the management of rare acral Ewing sarcomas. PATIENTS AND METHODS: We retrospectively reviewed the records of 10 patients with bony Ewing sarcomas located distal to the elbow joint. The group included 9 male and 1 female patient with a mean age at diagnosis of 20±12 years and a mean follow-up of 19 years. RESULTS: All patients presented with a primary complaint of a painful mass. The most common location was the metacarpal (n=4). Patients were treated with chemotherapy and either surgery (n=7) or definitive radiotherapy (n=3). The mean tumor size and necrosis on the resected specimens were 4±1 cm and 87% (range=30-100%), respectively. There was one case of local progression in a patient treated with definitive radiotherapy, which led to an amputation. Four patients developed metastatic disease, most commonly to the lungs. The 5-year survival free of metastatic disease or death due to disease was 55% and 60%, respectively. CONCLUSION: Acral Ewing sarcoma is rare. Combined chemotherapy and surgery lead to definitive local control in all patients, with an acceptable functional outcome.

Impact of tumour stage on the surgical outcomes of scapular chondrosarcoma.

PURPOSE: Chondrosarcomas are common primary bone tumours in adults, often affecting the flat bones. Oncologic outcomes are often tied to tumour grade; however, grade is only a factor in the aggressiveness of a tumor. Extracompartmental extension, or tumor stage, has been found to be predictive of a poor outcome in other flat bone chondrosarcomas; however, this relationship has not been identified in the scapula. The purpose of the current study was to analyze the impact of tumour stage on the outcome of patients with scapular chondrosarcoma. METHODS: Thirty-nine patients (26 males:13 females) with a mean age of 46 ± 17 undergoing surgical resection of a scapular chondrosarcomas were reviewed. Most patients had grade 1 (n = 24) tumors, with 26 (67%) having extracompartmental extension. The mean follow-up was eight years. RESULTS: The ten year disease-specific survival was 77%. High-grade tumours (HR 18.15, p < 0.01) were associated with death due to disease. The ten year local recurrence- and metastatic-free survival were 77% and 74%. Positive surgical margins (HR 8.85, p < 0.01) were associated with local recurrence, and local recurrence was associated with metastatic disease (HR3.37, p = 0.04). All disease recurrences and death due to disease occurred in patients with extracompartmental extension (p < 0.05). CONCLUSION: Extracompartmental extension was associated with a worse oncologic outcome in patients with scapular chondrosarcomas. Positive margins were associated with local recurrence, which was associated with metastatic disease; wide local excision with negative margins should be a goal for all patients, regardless of tumour grade.

Preoperative Risk Factors for Fibrosarcomatous Transformation in Dermatofibrosarcoma Protuberans.

BACKGROUND/AIM: Dermat of ibrosarcoma protuberans (DFSP) is a soft-tissue sarcoma with a high risk of local recurrence, though typically never metastasizes. DFSP can transform into high-grade fibrosarcoma (DFSP-FS), which has a risk of metastasis. Currently, treatment for DFSP includes Moh's micrographic surgery (MMS); however, this is not recommended for DFSP-FS. Often, the transformation to DFSP-FS is not recognized until the final histological diagnosis. At that point, wide local excision (WLE) of a previous MMS site can be morbid. As such, we analyzed patient risk factors to allow identification of DFSP-FS transformation at presentation. PATIENTS AND METHODS: We reviewed 368 (174 female, 194 male) patients with a mean age of 42 years from two sarcoma centers. A total of 319 (87%) patients had a history of DFSP and 49 (13%) had DFSP-FS. RESULTS: When comparing patients with a DFSP to those with a DFSP-FS, patients with a DFSP-FS were more likely (p<0.05) to be older, female and with larger tumors. A painful mass and rapidly enlarging mass were associated with DFSP-FS. CONCLUSION: Patients who presented with DFSP-FS were found to typically have a larger, painful, and growing mass. Patients with these features should be referred for WLE over MMS at presentation.

Free Functional Latissimus Dorsi Reconstruction of the Quadriceps and Hamstrings following Oncologic Resection of Soft Tissue Sarcomas of the Thigh.

BACKGROUND: Limb-salvage surgery combined with radiotherapy has become the primary treatment for soft tissue sarcomas of the extremity. Free functional latissimus flaps (FFLF) are an option to restore function in the setting of volumetric muscle loss. The purpose of the current study was to examine the use of FFLF in patients undergoing resection of thigh sarcoma. METHODS: Twelve patients with a sarcoma involving the hamstring (n = 6), quadriceps (n = 5), or combined (n = 1) defects which included multiple muscle groups were reviewed. This included 9 males and 3 females with a mean age and body mass index of 56 ± 12 years and 31.3 ± 5.7 kg/m2. RESULTS: The mean defect volume and operative time was 3,689 ± 2,314 cm3 and 587 ± 73 minutes. Following reconstruction, the mean knee range of motion (ROM), MSTS93 score, and muscle strength was 89 ± 24°, 90 ± 15%, and 4 ± 1; with 75% of patients ambulating without gait aids. Seven (58%) patients sustained a complication, namely, delayed wound healing (n = 2). CONCLUSION: Although there was a high incidence of complications, FFLF can restore active knee ROM and function, with most patients ambulating without gait aids following reconstruction of large oncologic defects in the thigh.

Comparison of flap reconstruction for soft tissue sarcomas of the foot and ankle.

BACKGROUND: Foot and ankle soft tissue sarcomas (STS) are challenging for reconstruction due to limited surrounding soft tissue and weight-bearing requirements. Currently, there is a paucity of data examining the outcome of flap reconstruction following resection of a foot and ankle sarcoma. METHODS: We reviewed 44 (31 female, 13 male) patients with STS arising from the ankle or foot which required coverage in the form of a free (n = 21), pedicled (n = 13), or rotational perforator flap (n = 10). The mean tumor size was 6 ± 5 cm, with 39 (89%) patients receiving radiotherapy. The mean follow-up was 10 ± 7 years. RESULTS: There were no cases of amputation due to flap failure, with a 10-year limb salvage rate of 84%. Complications occurred in 19 (43%) patients, most commonly wound infections. There was no difference in the incidence of complications between patients undergoing a free flap and pedicled or perforator flap (odds ratio = 0.97, p = 1.0); with no difference in the mean Musculoskeletal Tumor Society (MSTS) score between patients with a free flap versus a pedicled/perforator flap (84% vs. 76%, p = 0.11). CONCLUSION: Flap reconstruction is an essential part of limb salvage for foot and ankle STS. At final follow-up nearly all the patients are ambulatory with an acceptable MSTS score.

Anatomic total shoulder arthroplasty for primary glenohumeral osteoarthritis is associated with excellent outcomes and low revision rates in the elderly.

BACKGROUND: The relative indications of anatomic total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA) continue to evolve. Some surgeons favor RSA over TSA for elderly patients with primary glenohumeral osteoarthritis (GHOA) and an intact rotator cuff due to fear of a postoperative (secondary) rotator cuff tear in this age group. However, RSA is associated with unique complications and a worse functional arc of motion compared with TSA. Therefore, it is important to understand the clinical outcomes and rates of revision surgery and secondary rotator cuff tears in elderly patients undergoing TSA. METHODS: Between January 1, 2010, and December 31, 2017, 377 consecutive TSAs were performed for primary GHOA in 340 patients 70 years of age or older. The mean age at surgery was 76.2 years (standard deviation [SD], 4.9). Clinical evaluation included pain, motion, and American Shoulder and Elbow Surgeons score. Radiographs were reviewed for preoperative morphology and postoperative complications. All complications and reoperations were recorded. The average clinical follow-up time was 3.3 years (SD, 2.0). Statistical analyses were performed, and Kaplan-Meier implant survival estimates were calculated. For all analyses, a P value <.05 was considered statistically significant. RESULTS: The mean pain visual analog scale and American Shoulder and Elbow Surgeons score at the final follow-up were 1.6 (SD, 2.2) and 78.0 (SD, 17.8), respectively. Forward elevation and external rotation increased from 96° (SD, 30°) and 26° (SD, 20°) preoperatively to 160° (SD, 32°) and 64° (SD, 26°) postoperatively (P < .001 for each). The percentage of patients who had internal rotation to L5 or greater increased from 24.8% preoperatively to 71.8% postoperatively (P < .001). Revision surgery was performed in 3 shoulders (0.8%), and the 5-year implant survival estimate was 98.9% (95% confidence interval: 97.3%-100%). There were 3 medical (0.8%), 10 minor surgical (2.7%), and 5 major surgical (1.3%) complications. No shoulder had radiographic evidence of humeral component loosening, whereas 7 (2%) had evidence of some degree of glenoid component loosening. In total, there were 5 secondary rotator cuff tears (1.3%), of which 2 (0.5%) required revision surgery. CONCLUSION: Elderly patients with primary GHOA and an intact rotator cuff have excellent clinical and radiographic outcomes after anatomic TSA, with high implant survival rates and a low incidence of secondary rotator cuff tears in the first 5 postoperative years. Age greater than 70 by itself should not be considered an indication for RSA over TSA.

Outcome of Soft-tissue Reconstruction in the Setting of Combined Preoperative and Intraoperative Radiotherapy for Extremity Soft-tissue Sarcomas.

BACKGROUND/AIM: Reconstruction for soft-tissue sarcomas is complex and often uses soft-tissue flaps. To preserve critical structures, intraoperative radiotherapy (IORT) can be used to boost the total dose to these critical structures and close margins; however, there are limited data on the outcome of soft-tissue reconstruction in patients treated with IORT. PATIENTS AND METHODS: Twenty patients received IORT with soft-tissue flap coverage. There were 14 tumors of the lower extremities and six of the upper, including seven free-flaps and 13 pedicle flaps. Mean preoperative and IORT doses were 49.4 Gy and 10.4 Gy, respectively, with a mean total dose of 59.8 Gy. RESULTS: Seven (35%) patients had a complication, most commonly an infection (n=4, 27%). Total flap loss occurred in one treated with pedicle flap. Four (20%) patients suffered a radiation-associated fracture. At the final follow-up, the mean Musculoskeletal Tumor Society Score was 75±11%. CONCLUSION: Complications and postoperative fractures were common with IORT, however, there were no cases requiring amputation.