Stress shielding following radial head arthroplasty: the impact of preoperative bone quality.

INTRODUCTION: We sought to assess if the medullary diameter to cortical width ratio (MD:CW), canal flair index (CFI), and canal fill (CF) of the proximal radius were associated with the presence of Stress shielding (SS) after a MoPyC radial head arthroplasty (RHA). MATERIAL & METHOD: We conducted a retrospective, international, multicenter (4 centers) study. A total of 100 radial head arthroplasties in 64 women and 36 men with a mean age of 58.40 years ±14.90 (range, 25.00; 91.00) were included. Radiographic measurements, including MD:CW, CFI, CF, and postoperative SS were captured at a mean follow-up of 3.9 years ±2.8 (range, 0.5-11). RESULTS: Stress shielding was identified in 60 patients. Mean preoperative MD:CW, CFI, and CF were 0.55 ±0.09, 1.05 ±0.18 and 0.79±0.11, respectively. The presence of SS was significantly associated with MD:CW (aOR=13.66; p=0.001), and expansion of the stem (aOR=3.78; p=0.001). The amount of the SS was significantly correlated with expansion of the stem (aß 4.58; p<0.001). CONCLUSIONS: Our study found that MD:CW was an independent risk factor of SS after Mopyc RHA. Patients with longer and larger diameter (auto-expansion) Mopyc stems were also at significantly increased risk of SS. Further studies involving multiple implants designs are needed to confirm the preliminary observations presented in the current study.

Simple acute postero-lateral elbow dislocation: A historical perspective.

PURPOSE: The aims of this study were to summarize (1) the historical knowledge of the posterolateral elbow dislocation (PLED) pattern and the biomechanical, radiographic, and clinical data that engendered its evolution; and (2) to help clinicians better understand the management of PLED. METHODS: A literature search was performed using Ovid, Scopus and Cochrane Library, and the Medical Subject Headings vocabulary. Results are discussed as a chronologic review of the relevant literature between 1920-2022. RESULTS: In 1966 Osborn and Cotterill were the first to describe posterolateral rotatory instability (PLRI) causing the PLED. Several theories on PLED were then published by others surgeons as our understanding of elbow biomechanics continued to improve. Multiple treatment protocols have been designed based on the aforementioned theories. Conservative and surgical treatment for PLED provides excellent functional outcomes. However, high rates of persistent pain stiffness and instability have been reported long-term, and no single approach to treatment has been widely accepted. CONCLUSION: Despite a growing body of biomechanical evidence, there is no consensus surgical indication for the treatment of PLED. Both conservative and surgical management result in satisfactory functional outcomes after PLED. However, elevated rates of residual pain, and instability have also been described and may limit heavy labor and sports participation. The next challenge for elbow surgeons will be to identify those patients who would benefit from surgical stabilization following PLED.

Osteoid osteomas of the hip: a well-recognized entity with a proclivity for misdiagnosis.

OBJECTIVES: The diagnosis of osteoid osteomas (OO) about the hip can be challenging as presenting symptoms can mimic other, more common, periarticular pathologies. Our aims were to identify the most common misdiagnoses and treatments, mean delay in diagnosis, characteristic imaging features and provide tips for avoiding diagnostic imaging pitfalls for patients with OO of the hip. METHODS: We identified 33 patients (34 tumors) with OO about the hip who were referred for radiofrequency ablation between 1998 and 2020. Imaging studies reviewed included radiographs (n = 29), CT (n = 34), and MRI (n = 26). RESULTS: The most common initial diagnoses were femoral neck stress fracture (n = 8), femoroacetabular impingement (FAI) (n = 7), and malignant tumor or infection (n = 4). The mean time from symptom onset to diagnosis of OO was 15 months (range, 0.4-84). The mean time from initial incorrect diagnosis to OO diagnosis was 9 months (range, 0-46). CONCLUSIONS: The diagnosis of OO of the hip is challenging, with up to 70% of cases initially misdiagnosed as a femoral neck stress fracture, FAI, bone tumor, or other joint pathology in our series. Consideration of OO in the differential diagnosis of hip pain in adolescent patients and awareness of the characteristic imaging findings are critical for making an accurate diagnosis. KEY POINTS: • The diagnosis of osteoid osteoma of the hip can be challenging, as demonstrated by long delays in time to initial diagnosis and high rates of misdiagnoses which can lead to inappropriate interventions. • Familiarity with the spectrum of imaging features of OO, especially on MRI, is imperative given the increase in the utilization of this modality for the evaluation of young patients with hip pain and FAI. • Consideration of OO in the differential diagnosis of hip pain in adolescent patients and awareness of the characteristic imaging findings, including bone marrow edema and the utility of CT, are critical for making a timely and accurate diagnosis.

Analysis of 101 Mechanical Failures in Distal Femur Fractures Treated with 3 Generations of Precontoured Locking Plates.

OBJECTIVES: To evaluate mechanical treatment failure in a large patient cohort sustaining a distal femur fracture treated with a distal femoral locking plate (DFLP). DESIGN: This retrospective case-control series evaluated mechanical treatment failures of DFLPs. SETTING: The study was conducted at 8 Level I trauma centers from 2010 to 2017. PATIENTS AND PARTICIPANTS: One hundred one patients sustaining OTA/AO 33-A and C distal femur fractures were treated with DFLPs that experienced mechanical failure. INTERVENTION: The intervention included the treatment of a distal femur fracture with a DFLP, affected by mechanical failure (implant failure by loosening or breakage). MAIN OUTCOME MEASURE: The main outcome measures included injury and DFLP details; modes and timing of failure were studied. RESULTS: One hundred forty-six nonunions were found overall (13.4%) including 101 mechanical failures (9.3%). Failures occurred in different manners, locations, and times depending on the DFLPs. For example, 33 of 101 stainless steel (SS) plates (33%) failed by bending or breaking in the working length, whereas no Ti plates failed here ( P < 0.05). Eleven of 12 failures with titanium-Less Invasive Stabilization System (92%) occurred by lost shaft fixation, mostly by the loosening of unicortical screws (91%). Sixteen of 44 variable -angled-LCP failures (36%) occurred at the distal plate-screw junction, whereas only 5 of 61 other DFLPs (8%) failed this way ( P < 0.05). Distal failures occurred on average at 23.7 weeks compared with others that occurred at 38.4 weeks ( P < 0.05). Variable -angled-LCP distal screw-plate junction failures occurred earlier (mean 21.4 weeks). CONCLUSION: Nonunion and mechanical failure occurred in 14% and 9% of patients, respectively, in this large series of distal femur fracture treated with a DFLP. The mode, location, presence of a prosthesis, and timing of failure varied depending on the characteristics of DFLP. This information should be used to optimize implant usage and design to prolong the period of stable fixation before potential implant failures occur in patients with a prolonged time to union. LEVEL OF EVIDENCE: Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Midterm outcomes allograft prosthetic composite reconstruction for massive bone loss at the elbow.

BACKGROUND: Revision of a loose total elbow arthroplasty (TEA) is challenging, particularly in the context of massive bone loss (MBL). The use of an allograft prosthetic composite (APC) at the elbow is rare, typically reserved as a salvage procedure for MBL. Thus, limited data describing the outcomes of APCs are available in current literature. HYPOTHESIS: The authors hypothesize that short to midterm clinical outcomes of APC for MBL about the elbow are satisfactory. PATIENTS AND METHODS: Between 2009 and 2018, 6 APCs implanted with a semi-constrained Coonrad Morrey prosthesis were performed in 5 females and 1 male. Median patient age was 70 years (range, 49-76 years). The indication for revision was aseptic loosening in all 6 cases (6 humeral and 2 ulnar). Median follow-up was 3.5 years (range, 2-6.7 years). Functional outcomes including Mayo Elbow Performance Score (MEPS), Visual Analog Scale (VAS), range of motion (ROM), and radiographic outcomes were assessed for all patients. RESULTS: Median MEPS and VAS scores were 75 (range, 40-90), and 0 (range, 0-8) at latest follow-up, respectively. Median postoperative flexion-extension and prono-supination arcs were 90̊ (range, 70-140̊) and 150 (range, 100-160̊), respectively. Allograft incorporation was noted in 5 (83%) patients; all prostheses were well-fixed. In total, 4 patients (63%) experienced 5 complications (83%) including periprosthetic fracture (n=2), ulnar neuropathy (n=1), aseptic loosening (n=1), and wound dehiscence (n=1). Two (33%) required reoperation with prosthetic retention. CONCLUSION: Elbow reconstruction using allograft prosthetic composite is a viable option for patients with MBL following TEA. The midterm functional outcomes are satisfactory with no revisions required, despite a relatively high rate of complications. Further long-term studies with larger cohorts are needed to better elucidate long-term outcomes and reasons for failure. LEVEL OF EVIDENCE: IV; therapeutic study (case series [no, or historical, control group]).

Bedside hip aspiration results in decrease in total general anesthesia time in pediatric patients: A multicenter study.

Purpose: The purpose of this study is to compare pediatric hip aspiration in the operating room under general anesthesia or via bedside aspiration under moderate sedation and delineate the anesthetic time required. Methods: A database query conducted at two academic institutions identified all patients under the age of 17 who underwent hip aspiration between 2000 and 2017. At one institution, aspiration was performed in the operating room under general anesthesia. Patients were kept anesthetized until cell count was complete. At the second institution, aspiration was performed in the emergency room at bedside under sedation. The medical record was reviewed for demographic data, hip aspiration results, diagnoses, treatment, and anesthesia time. Results: A total of 233 patients (233 hips) with a mean age of 7.2 years were identified. Seventy-five patients underwent aspiration in the operating room, and 158 patients underwent bedside aspiration. Patients with a negative aspiration averaged 87 min under anesthesia when performed in the operating room and 29 min under sedation when performed at bedside. Patients with a negative aspiration performed in the operating room after 5 pm averaged 99 min under anesthesia, and 73 min under anesthesia when performed between 7 am and 5 pm (p < 0.01). Seventy-eight (49%) patients who underwent bedside aspiration did not require operative intervention and therefore avoided general anesthesia. Conclusion: Pediatric hip aspiration performed in the operating room results in prolonged anesthesia times while synovial fluid is transported and processed. Anesthesia times are significantly longer after 5 pm. Bedside aspiration resulted in significantly less anesthesia exposure, with half of patients undergoing bedside aspiration avoiding general anesthesia altogether. Level of evidence: Level III.

Immune cell populations differ in patients undergoing revision total knee arthroplasty for arthrofibrosis.

Arthrofibrosis following total knee arthroplasty (TKA) is a debilitating condition typically diagnosed based on clinical findings. To gain insight into the histopathologic immune cell microenvironment of arthrofibrosis, we assessed the extent of tissue fibrosis and quantified immune cell populations in specific tissue regions of the posterior capsule. We investigated specimens from three prospectively-collected, matched cohorts, grouped as patients receiving a primary TKA for osteoarthritis, revision TKA for arthrofibrosis, and revision TKA for non-arthrofibrotic, non-infectious reasons. Specimens were evaluated using hematoxylin and eosin staining, picrosirius red staining, immunofluorescence, and immunohistochemistry with Aperio®-based digital image analysis. Increased collagen deposition and increased number of α-SMA/ACTA2 expressing myofibroblasts were present in the arthrofibrosis group compared to the two non-arthrofibrotic groups. CD163 + macrophages were the most abundant immune cell type in any capsular sample with specific enrichment in the synovial tissue. CD163 + macrophages were significantly decreased in the fibrotic tissue region of arthrofibrosis patients compared to the patients with primary TKA, and significantly increased in adipose tissue region of arthrofibrotic specimens compared to non-arthrofibrotic specimens. Synovial CD117 + mast cells were significantly decreased in arthrofibrotic adipose tissue. Together, these findings inform diagnostic and targeted therapeutic strategies by providing insight into the underlying pathogenetic mechanisms of arthrofibrosis.

Terrible triad injury of the elbow: a historical perspective.

PURPOSE: The aims of this study are to summarize (1) the history of terrible triad injury (TTi) treatment and (2) the clinical and biomechanical data that engendered its evolution. METHODS: A literature search was performed using five electronic databases. Results were discussed as a chronologic review of the relevant literature between 1920 and 2022. RESULTS: In 1962, Osborne was the first to describe a link between elbow dislocation, radial head fracture, and lateral collateral ligament complex injury via a novel mechanism: posterolateral rotatory instability (PLRI). Given that untreated elbow instability leads to post-traumatic osteoarthritis (PTOA), there has been increasing interest in elbow biomechanics since the 1980s. Data from studies in that period revolutionized the approach to elbow instability. The authors demonstrated that TTi could occur via a PLRI mechanism with a disruption of the lateral collateral ulnar ligament and a functionally competent anterior medial collateral ligament (aMCL). Since the 1990s, due to the difficulty in identifying its pathoanatomic features, some began to speculate about a sequence of injuries and mechanisms leading to TTi. However, the clinical literature has largely been unable to reproduce in vitro findings describing the pathomechanics of TTi. Some aspects of treatment remain controversial including systematic coronoid and aMCL repair. CONCLUSION: Despite a growing body of biomechanics data, there is no widely accepted surgical protocol for the treatment of TTi. Functional outcomes among patients have greatly improved. Better diagnosis and treatment of infra-clinical instability after a TTi may be an important stepping stone to prevent the onset of moderate/severe PTOA.

Total Denervation of the Elbow: Cadaveric Feasibility Study.

PURPOSE: Total elbow arthroplasty for the treatment of patients with severe elbow osteoarthritis is associated with postoperative activity limitations and risk of midterm complications. Elbow denervation could be an attractive therapeutic option for young, active patients. The aim of our study was to assess the feasibility of selective total elbow denervation via 2 anteriorly based approaches. METHODS: Selective total elbow denervation was performed in 14 cadaver elbows by 2 fellowship-trained elbow surgeons. Lateral and medial approaches to the elbow were used. The length of skin incisions and the minimum distance between them were noted. The number of articular branches identified and their respective distances from the lateral or medial epicondyle of the humerus were recorded. RESULTS: The anterolateral and anteromedial approaches allowed for the identification of all mixed and sensory nerves in all 14 cases. The mean number of resultant articular branches per cadaver was 1 for the musculocutaneous nerve, 2 (range, 1-3) for the radial nerve, 1 (range, 1-3) for the posterior cutaneous nerve of the forearm, 2 (range, 1-3) for the ulnar nerve, and 2 (range, 1-3) for the medial antebrachial cutaneous nerve; the collateral ulnar nerve was connected directly to the capsule. The length of the medial and lateral incisions was 15 cm (range, 12-18 cm) and 12 cm (range, 10-16 cm), respectively. The mean minimum distance between the incisions was 7.5 cm (range, 6.7-8.5 cm). CONCLUSIONS: The findings suggest that selective elbow denervation via 2 approaches is feasible. CLINICAL RELEVANCE: Selective elbow denervation via 2 approaches is feasible. Surgeons should target the articular branches of the musculocutaneous, radial, ulnar, and collateral ulnar nerves, posterior cutaneous nerve of the forearm, as well as medial antebrachial cutaneous nerves when carrying out this procedure.

Primary and revision total hip arthroplasty with uncemented acetabular components in patients with Paget's disease.

INTRODUCTION: Paget's disease affects 3-4% of the population; however, literature describing outcomes of total hip arthroplasty (THA) in this population are limited. Given the known concerns with bleeding, heterotopic ossification (HO), and component loosening, we describe our results with primary and revision THAs in Paget's disease with emphasis on implant survivorship, radiographic results, and clinical outcomes. METHODS: We identified 25 THAs performed with contemporary uncemented acetabular components in patients with Paget's disease from 1999 to 2014. Mean age and follow-up were 78 and 7 years. RESULTS: In primary THAs, survivorship free from aseptic acetabular and femoral loosening was 100% and 94% at 8 years. 7 patients (41%) received blood transfusions. HO was seen in 9 (53%). Mean Harris Hip Score (HHS) improved from 49 to 76. In revision THAs, survivorship free from acetabular and/or femoral aseptic loosening was 100% at 5 years. 3 patients (38%) received a transfusion. HO was seen in 5 (63%). Mean HHS improved from 52 to 77. There were no radiographic signs of aseptic loosening among unrevised cases in either group. DISCUSSION: Our investigation demonstrates that concerns with acetabular fixation in Paget's disease have been mitigated with contemporary uncemented acetabular components. Complications previously noted, namely intraoperative bleeding and HO, continue to be of concern.

Atraumatic proximal radial nerve entrapment. Illustrative cases and systematic review of literature.

PURPOSE: The aims of the present study were to describe atraumatic proximal radial nerve entrapment (PRNE) and potential strategies for management. MATERIALS AND METHODS: We performed a comprehensive search of 4 electronic databases for studies pertaining to patients with atraumatic PRNE. Studies published between 1930 and 2020 were included. Clinical presentation, nerve conduction studies, electromyography, and treatment methods were reviewed. In order to outline management strategies, 2 illustrative cases of acute PRNE were presented. RESULTS: We analyzed 12 studies involving 21 patients with 22 PRNE (15 acute and 7 progressive). Sudden or repetitive elbow extension with forceful muscle contraction (n = 16) was the primary mechanism of injury. The two main sites of entrapment were the fibrous arch (n = 7) and hiatus of the lateral intermuscular septum (n = 7). Conservative treatment was performed in 4 patients and allowed for complete clinical recovery in all cases. The remaining 18 patients underwent epineurolysis (n = 16) or resection/repair of hourglass-like constriction (n = 2) between 1.5- and 120-months following diagnosis. Twelve patients experience complete recovery, while partial or no clinical recovery was reported in 1 and 4 cases, respectively; the outcome was unknown in 1 case. CONCLUSIONS: Atraumatic PRNE is rare and remains challenging with respect to diagnosis and treatment. Current literature suggests that primary sites of entrapment are the fibrous arch and hiatus of the radial nerve at the time of forceful elbow extension. LEVEL OF EVIDENCE: Case series (IV) & systematic review (I).

Distal femoral replacement versus ORIF for severely comminuted distal femur fractures.

INTRODUCTION: Distal femoral replacement (DFR) and open reduction and internal fixation (ORIF) are surgical options for comminuted distal femur fractures. Comparative outcomes of these techniques are limited. The aims of this study were to compare implant survivorship, perioperative factors, and clinical outcomes of DFR vs. ORIF for comminuted distal femur fractures. METHODS: Ten patients treated with rotating hinge DFRs for AO/OTA 33-C fractures from 2005 to 2015 were identified and matched 1:2 based on age and sex to 20 ORIF patients. Patients treated with DFR and ORIF had similar ages (80 vs. 76 years, p = 0.2) and follow-up (20 vs. 27 months, p = 1.0), respectively. Implant survivorship, length of stay (LOS), anesthetic time, estimated blood loss (EBL), ambulatory status, knee range of motion (ROM), and Knee Society scores (KSS) were assessed at final follow-up. RESULTS: Survivorship free from any revision at 2 years was 90% and 65% for the DFR and ORIF groups, respectively (p = 0.59). Survivorship free from any reoperation at 2 years was 90% for the DFR group and 50% for the ORIF group (p = 0.16). Three ORIF patients (15%) went on to nonunion and two went on to delayed union. Mean EBL and LOS were significantly higher for the DFR group: 592 mL vs. 364 mL, and 13 vs. 6.5 days, respectively. Knee ROM (p = 0.71) and KSSs (p = 0.36) were similar between groups. CONCLUSIONS: Comminuted distal femur fractures treated with DFR trended toward lower revision and reoperation rates, with similar functional outcomes when compared to ORIF. We noted a trend toward increased EBL and LOS in the DFR group. LEVEL OF EVIDENCE: Level IV.

Does a combined screw and dowel construct improve tibial fixation during anterior cruciate ligament reconstruction?

PURPOSE: The aims of the present study were to compare the biomechanical properties of tibial fixation in hamstring-graft ACL reconstruction using interference screw and a novel combination interference screw and dowel construct. MATERIAL AND METHODS: We compared the fixation of 30 (2- and 4-stranded gracilis and semitendinosis tendons) in 15 fresh-frozen porcine tibiae with a biocomposite resorbable interference screw (Group 1) and a screw and dowel construct (Group 2). Each graft was subjected to load-to-failure testing (50 mm/min) to determine maximum load, displacement at failure and pullout strength. RESULTS: There were no significant differences between the biomechanical properties of the constructs. Multivariate analysis demonstrated that combination constructs (ß = 140.20, p = 0.043), screw diameter (ß = 185, p = 0.006) and 4-strand grafts (ß = 51, p = 0.050) were associated with a significant increase in load at failure. Larger screw diameter was associated with increased construct stiffness (ß = 20.15, p = 0.020). CONCLUSION: The screw and dowel construct led to significantly increased fixation properties compared to interference screws alone in a porcine model. Increased screw diameter and utilization of 4-strand ACL grafts also led to improvement in load-to-failure of the construct. However, this is an in vitro study and additional investigations are needed to determine whether the results are reproducible in vivo. LEVEL OF EVIDENCE: Level V; Biomechanical study.

Factors Affecting the Risk of Aseptic Patellar Complications in Primary TKA Performed with Cemented All-Polyethylene Patellar Resurfacing.

BACKGROUND: Patellar complications are a consequential cause of failure of primary total knee arthroplasty (TKA). The purpose of this study was to evaluate the association of demographic and patient factors with the long-term risk of patellar complications as a function of time in a very large cohort of primary TKAs performed with patellar resurfacing. METHODS: We identified 27,192 primary TKAs utilizing cemented all-polyethylene patellar components that were performed at a single institution from 1977 through 2015. We evaluated the risk of any aseptic patellar complication and any aseptic patellar reoperation or revision, subanalyzed risks of reoperation or revision for loosening, maltracking/instability, and wear, and evaluated the risk of clinical diagnosis of patellar fracture and clunk/crepitus. The mean age at TKA was 68 years (range, 18 to 99 years); 57% of the patients were female. The mean body mass index (BMI) was 32 kg/m2. The primary diagnosis was osteoarthritis in 83%, and 70% of the TKAs were posterior-stabilized. Median follow-up was 7 years (range, 2 to 40 years). Risk factors for each outcome were evaluated with Cox regression models. RESULTS: Nine hundred and seventy-seven knees with all-polyethylene patellae developed patellar complications. Survivorship free from any aseptic patellar complication was 93.3% at 20 years. Twenty-year survivorship free from any aseptic patellar reoperation was 97.3% and free from any aseptic patellar revision was 97.4%. Fifteen-year survivorship for the same end points for procedures performed from 2000 to 2015 was 95.7%, 99.2% and 99.3% respectively, representing substantial improvements compared with implants placed before 2000. Univariate analysis demonstrated that male sex (hazard ratio [HR], 1.4), an age of <65 years (HR, 1.3), and a BMI of ≥30 kg/m2 (HR, 1.2) were associated with increased risk of patellar complications (all p ≤0.01). Posterior-stabilized designs were associated with fewer patellar reoperations and revisions overall (HR, 0.4 and 0.4; p < 0.001) but higher risk of patellar clunk/crepitus (HR, 14.1; p < 0.001). CONCLUSIONS: The 20-year survivorship free from any aseptic patellar complication in this series of cemented all-polyethylene patellae was 93%. Important risk factors for any aseptic patellar complication were male sex, an age of <65 years, a BMI of ≥30 kg/m2, and a patella implanted before 2000. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Outcomes of operatively treated interprosthetic femoral fractures.

AIMS: The prevalence of ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is rising in concert with life expectancy, putting more patients at risk for interprosthetic femur fractures (IPFFs). Our study aimed to assess treatment methodologies, implant survivorship, and IPFF clinical outcomes. METHODS: A total of 76 patients treated for an IPFF from February 1985 to April 2018 were reviewed. Prior to fracture, at the hip/knee sites respectively, 46 femora had primary/primary, 21 had revision/primary, three had primary/revision, and six had revision/revision components. Mean age and BMI were 74 years (33 to 99) and 30 kg/m2 (21 to 46), respectively. Mean follow-up after fracture treatment was seven years (2 to 24). RESULTS: Overall, 59 fractures were classified as Vancouver C (Unified Classification System (UCS) D), 17 were Vancouver B (UCS B). In total, 57 patients (75%) were treated with open reduction and internal fixation (ORIF); three developed nonunion, three developed periprosthetic joint infection, and two developed aseptic loosening. In all, 18 patients (24%) underwent revision arthroplasty including 13 revision THAs, four distal femoral arthroplasties (DFAs), and one revision TKA: of these, one patient developed aseptic loosening and two developed nonunion. Survivorship free from any reoperation was 82% (95% confidence interval (CI) 66.9% to 90.6%) and 77% (95% CI 49.4% to 90.7%) in the ORIF and revision groups at two years, respectively. ORIF patients who went on to union tended to have stemmed knee components and greater mean interprosthetic distance (IPD = 189 mm (SD 73.6) vs 163 mm (SD 36.7); p = 0.546) than nonunited fractures. Patients who went on to nonunion in the revision arthroplasty group had higher medullary diameter: cortical width ratio (2.5 (SD 1.7) vs 1.3 (SD 0.3); p = 0.008) and lower IPD (36 mm (SD 30.6) vs 214 mm (SD 32.1); p < 0.001). At latest follow-up, 95% of patients (n = 72) were ambulatory. CONCLUSION: Interprosthetic femur fractures are technically and biologically challenging cases. Individualized approaches to internal fixation versus revision arthroplasty led to an 81% (95% CI 68.3% to 88.6%) survivorship free from reoperation at two years with 95% of patients ambulatory. Continued improvements in management are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):122-128.

Outcomes of Vancouver C Periprosthetic Femur Fractures.

BACKGROUND: Periprosthetic femur fractures (PFFs) that occur distal to a total hip arthroplasty, Vancouver C fractures, are challenging to treat. We aimed to report patient mortality, reoperations, and complications following Vancouver C PFFs in a contemporary cohort all treated with a laterally based locking plate. METHODS: We retrospectively identified 42 consecutive Vancouver C PFFs between 2004 and 2018. There was a high prevalence of comorbidities, including 9 patients with neurologic conditions, 9 with a history of cancer, 8 diabetics, and 8 using chronic anticoagulation. Mean time from total hip arthroplasty to PFF was 6 years (range 1 month to 25 years). All fractures were treated with a laterally based locking plate. Fixation bypassed the femoral component in 98% of cases and extended as proximal as the lesser trochanter in 18%. Kaplan-Meier survival was used for patient mortality, and a competing risk model was used to analyze survivorship free of reoperation and nonunion. Mean follow-up was 2 years. RESULTS: Patient mortality was 5% at 90 days and 31% at 2 years. Cumulative incidence of reoperation was 13% at 2 years. There were 5 reoperations including revision osteosynthesis for nonunion and/or hardware failure (2), debridement and hardware removal for infection (2), and removal of hardware and total knee arthroplasty for post-traumatic arthritis (1). Cumulative incidence of nonunion was 10% at 2 years. CONCLUSION: Patients who sustained a Vancouver C PFFs had a high mortality rate (31%) at 2 years. Moreover, 13% of patients required a reoperation within 2 years, most commonly for infection or nonunion.

Midterm outcomes of 146 EVOLVE Proline modular radial head prostheses: a systematic review.

INTRODUCTION: The EVOLVE implant (Wright Medical Technology, Arlington, TN, USA) is a modular loose-fitting radial head prosthesis. The primary objective was to synthesize all available literature investigating the midterm clinical outcomes of the EVOLVE implant. MATERIALS AND METHODS: An electronic literature search in Pubmed/Medline, Scopus, EMBASE, and Cochrane library was performed querying for studies published in 2000-2017. Articles describing clinical and radiographical outcomes as well as reoperation were included. Outcomes of interest included range of motion, Mayo Elbow Performance Score, Disabilities of the Arm Shoulder and Hand, radiographic outcome, and reason for reoperation. RESULTS: A total of five articles consisting of 146 patients with EVOLVE implants were included. Mean patient age was 57.4 years (range 22-84), and 43.8% were males (n = 64). Mean follow-up was 4.8 years (range 1-14). Mean Mayo Elbow Performance Score and Disabilities of the Arm Shoulder and Hand score were 87.6 (range 30-100) and 18.9 (range 0-82), respectively. Midterm clinical results were good or excellent (Mayo Elbow Performance Score > 74) in 94 patients. Reoperation was observed in 12 patients, with implant revision required in 2 patients. The primary reason for reoperation was persistent stiffness (n = 9). CONCLUSION: Midterm outcomes of EVOLVE radial head prosthesis are satisfactory, and associated complication rates are low. Loose-fit implant method appears to be a reliable approach to avoid failure of radial head prosthesis by painful loosening.

Acquired Idiopathic Stiffness After Contemporary Total Knee Arthroplasty: Incidence, Risk Factors, and Results Over 25 Years.

BACKGROUND: Acquired idiopathic stiffness (AIS) remains a common failure mode of contemporary total knee arthroplasties (TKAs). The present study investigated the incidence of AIS and manipulation under anesthesia (MUA) at a single institution over time, determined outcomes of MUAs, and identified risk factors associated with AIS and MUA. METHODS: We identified 9771 patients (12,735 knees) who underwent primary TKAs with cemented, modular metal-backed, posterior-stabilized implants from 2000 to 2016 using our institutional total joint registry. Mean age was 68 years, 57% were female, and mean body mass index was 33 kg/m2. Demographic, surgical, and comorbidity data were investigated via univariate Cox proportional hazard models and fit to an adjusted multivariate model to access risk for AIS and MUA. Mean follow-up was 7 years. RESULTS: During the study period, 456 knees (3.6%) developed AIS and 336 knees (2.6%) underwent MUA. Range of motion (ROM) increased a mean of 34° after the MUA; however, ROM for patients treated with MUA was inferior to patients without AIS at final follow-up (102° vs 116°, P < .0001). Significant risk factors included younger age (HR 2.3, P < .001), increased tourniquet time (HR 1.01, P < .001), general anesthesia (HR 1.3, P = .007), and diabetes (HR 1.5, P = .001). CONCLUSION: Acquired idiopathic stiffness has continued to have an important adverse impact on the outcomes of a subset of patients undergoing primary TKAs. When utilized, MUA improved mean ROM by 34°, but patients treated with MUA still had decreased ROM compared to patients without AIS. Importantly, we identified several significant risk factors associated with AIS and subsequent MUA. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Sensory Innervation of the Hip Joint and Referred Pain: A Systematic Review of the Literature.

OBJECTIVES: The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches innervating the hip joint and the distribution of sensory receptors within its capsule. METHODS: Five electronic databases were queried, with the search encompassing articles published between January 1945 and June 2019. Twenty-one original articles providing a detailed description of sensory receptors around the hip joint capsule (n=13) and its articular branches (n=8) were reviewed. RESULTS: The superior portions of the anterior capsule and the labrum were found to be the area of densest nociceptive innervation. Similar to the distribution of nociceptors, mechanoreceptor density was found to be higher anteriorly than posteriorly. Hip joint capsular innervation was found to consistently involve the femoral and obturator nerves, which supply the anterior capsule, and the nerve to the quadratus femoris, which supplies the posterior capsule. The femoral, obturator, and superior gluteal nerves supply articular branches to the most nociceptor-rich region of the hip capsule. CONCLUSIONS: The femoral and obturator nerves and the nerve to the quadratus femoris were found to consistently supply articular branches to both the anterior and posterior capsule of the hip joint. The anterior capsule, primarily supplied by the femoral and obturator nerves, and the superior labrum appear to be the primary pain generators of the hip joint, given their higher density of nociceptors and mechanoreceptors. LEVEL OF EVIDENCE: Anatomy study, literature review.

Effect of Coronal Alignment on 10-Year Survivorship of a Single Contemporary Total Knee Arthroplasty.

Debate remains regarding the utility of mechanical axis alignment as a predictor of durability after total knee arthroplasty (TKA). Our study aimed to assess the effects of coronal alignment on implant durability, clinical outcomes, and radiographic results with a single fixed-bearing TKA design. All patients undergoing primary cemented TKA of a single design (Stryker Triathlon) from 2005-2007 with >10 years of follow-up and available pre-operative and post-operative hip-knee-ankle radiographs were included (n = 89). Radiographs were measured to determine coronal alignment and assessed for loosening. Mean preoperative mechanical axis alignment was -6° ± 6.7° (varus, range, -16°-23°), while mean post-operative alignment was -1° ± 2.7° (varus, range, -3°-15°). The aligned group was defined as knees with a post-operative mechanical axis of 0° ± 3° (n = 73) and the outlier group as those outside this range (n = 16). No patients underwent revision. Ten-year survivorship free from any reoperation was 99% and 100% in the aligned and outlier groups, respectively (p = 0.64). Knee Society scores improved significantly in both groups (p < 0.001) and did not differ at final follow-up (p = 0.15). No knees demonstrated radiographic evidence of loosening. Post-operative mechanical axis alignment within 3° of neutral was not associated with improved implant durability, clinical outcomes, or radiographic results at 10 years following primary TKA.