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.

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.

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.

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.

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.

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).

Treatment outcome of superficial leiomyosarcoma.

BACKGROUND: Nonuterine leiomyosarcomas (LMS) are common extremity soft-tissue sarcomas. Deep LMS are at an increased risk for recurrence; however, few studies have focused on superficial LMS. METHODS: We reviewed the clinicopathological features of 82 patients with a primary superficial LMS. The mean age and follow-up were 57 ± 15 and 7 ± 5 years. Depth was classified as dermal (based in the skin; n = 35, 43%) and subcutaneous (based below the dermis, above the fascia; n = 47, 57%) on the final resection specimen. Dermal cases were treated with negative margin resection, while subcutaneous tumors were evaluated by a multidisciplinary team for consideration of possible adjuvant therapy. RESULTS: The 10-year disease-specific survival (DSS) for superficial LMS was 90% with no difference (p = .18) in the 10-year DSS between patients with dermal (100%) and subcutaneous (86%) LMS. All disease recurrences occurred in subcutaneous LMS (17% vs. 0%, p = .02) and subcutaneous tumors had a worse10-year metastatic free survival (81% vs. 100%, p = .03). CONCLUSIONS: The results of this study suggest that dermal LMS can be managed with a negative margin resection alone. Although the prognosis for patients with subcutaneous LMS is quite favorable, there is some risk for local and distant recurrence, and such patients will benefit from multidisciplinary care.

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.

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.

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.

Ultrasound-Guided Proximal and Distal Suprascapular Nerve Blocks: A Comparative Cadaveric Study.

OBJECTIVES: The primary aim of our study was to evaluate and compare the accuracy of ultrasound (US)-guided distal suprascapular nerve (dSSN) and proximal SSN (pSSN) blocks. Secondary aims were to compare the phrenic nerve involvement between groups and to describe the anatomical features of the sensory branches of the dSSN. METHODS: pSSN and dSSN blocks were performed in 14 cadavers (28 shoulders). Ten mL of 0.2% ropivacaine colored with methylene blue was injected under US guidance. Accuracy was determined using SSN staining and the distance between predefined anatomical landmarks and the targeted SSN. The phrenic nerve (PN) was judged to be colored or not. The distribution of the sensory branches that originate from the 14 dSSNs is described. Quantitative data are expressed as median (range). RESULTS: The pSSN was dyed more frequently than the dSSN (13 vs 11, P = 0.59). The targeted SSN was close to the suprascapular notch (1.3 [0-5.2] cm) and the origin of the SSN (1.4 [0.2-4.5] cm) for dSSN and pSSN blocks, respectively (P = 0.62). For dSSN blocks, the most frequent injection site was the supraspinous fossa. Three PNs were marked in pSSN blocks, compared with none in dSSN blocks (P = 0.22). Three sensory branches were identified for all 14 dSSNs: the medial subacromial branch, the lateral subacromial branch, and the posterior glenohumeral branch. CONCLUSIONS: US-guided pSSN and dSSN blocks can be realized with accuracy. A distal approach to the SSN could be an alternative to interscalene brachial plexus block for the management of postoperative pain after shoulder surgery in high-respiratory risk patients.

Molecular pathology of adverse local tissue reaction caused by metal-on-metal implants defined by RNA-seq.

Total hip arthroplasty (THA) alleviates hip pain and improves joint function. Current implant design permits long-term survivorship of THAs, but certain metal-on-metal (MoM) articulations can portend catastrophic failure due to adverse local tissue reactions (ALTR). Here, we identified biological and molecular differences between periacetabular synovial tissues of patients with MoM THA failure undergoing revision THA compared to patients undergoing primary THA for routine osteoarthritis (OA). Analysis of tissue biopsies by RNA-sequencing (RNA-seq) revealed that MoM patient samples exhibit significantly increased expression of immune response genes but decreased expression of genes related to extracellular matrix (ECM) remodeling. Thus, interplay between local tissue inflammation and ECM degradation may account for the pathology and compromised clinical outcomes in select patients with MoM implants. We conclude that adverse responses of host tissues to implant materials result in transcriptomic modifications in patients with MoM implants that permit consideration of strategies that could mitigate ECM damage.

Sensory innervation of the human shoulder joint: the three bridges to break.

BACKGROUND: Painful shoulders create a substantial socioeconomic burden and significant diagnostic challenge for shoulder surgeons. Consensus with respect to the anatomic location of sensory nerve branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches (ABs) (1) innervating the shoulder joint and (2) the distribution of sensory receptors about its capsule and bursae. MATERIALS AND METHODS: Four electronic databases were queried, between January 1945 and June 2019. Thirty original articles providing a detailed description of the distribution of sensory receptors about the shoulder joint capsule (13) and its ABs (22) were reviewed. RESULTS: The suprascapular, lateral pectoral, axillary, and lower subscapular nerves were found to provide ABs to the shoulder joint. The highest density of nociceptors was found in the subacromial bursa. The highest density of mechanoreceptors was identified within the insertion of the glenohumeral ligaments. The most frequently identified innervation pattern comprised 3 nerve bridges (consisting of ABs from suprascapular, axillary, and lateral pectoral nerves) connecting the trigger and the identified pain generator areas rich in nociceptors. CONCLUSION: Current literature supports the presence of a common sensory innervation pattern for the human shoulder joint. Anatomic studies have demonstrated that the most common parent nerves supplying ABs to the shoulder joint are the suprascapular, lateral pectoral, and axillary nerves. Further studies are needed to assess both the safety and efficacy of selective denervation of the painful shoulders, while limiting the loss of proprioceptive function.

Modular Fluted Tapered Stems in Aseptic Oncologic Revision Total Hip Arthroplasty: A Game Changer?

BACKGROUND: Modular fluted tapered (MFT) stems are the most frequently used femoral component in revision total hip arthroplasties (THAs). Despite this, no data are available on how they perform in revision THA for oncologic salvage. This is a unique population, often with severe bone loss and prior radiation that extends the limits of uncemented femoral reconstruction. The aims of this study were to evaluate the implant survivorship, radiographic results, and clinical outcomes of MFT stems used for revision oncologic salvage. METHODS: We identified 17 patients treated initially with primary THA for an oncologic diagnosis (15 primary oncologic, 2 metastatic disease) who underwent subsequent femoral revision with an MFT stem. Mean age at revision was 66 years and 35% of patients were female. Mean follow-up was 4 years. Before revision, 5 of 17 had undergone local radiation. RESULTS: Ten-year survivorship free from aseptic loosening was 100%. The survivorship free of any reoperation was 76%. There were no femoral component fractures. Three patients were revised for recurrent instability, and 1 patient underwent irrigation and debridement for an acute infection. At most recent follow-up, no patient had radiographic evidence of progressive femoral component subsidence or failure of osteointegration. The mean Harris Hip Score improved from 29 preoperatively to 76 postoperatively (P < .0001). CONCLUSION: In this series of patients with cancer, many of whom had severe bone loss and/or prior local radiation, being treated with revision THA, there were no revisions for femoral component loosening and no cases of implant fracture. LEVEL OF EVIDENCE: III.

Evolution of Hip Dysplasia in Pediatric Patients With Prader-Willi Syndrome Treated With Growth Hormone Early in Development.

BACKGROUND: Prader-Willi syndrome (PWS) is a rare genetic disorder characterized by obesity, hypotonia, feeding difficulties, obesity, musculoskeletal manifestations including scoliosis, and hip dysplasia (HD). The aim of this study was to characterize the clinical and radiographic evolution of HD in the pediatric PWS population. METHODS: The authors performed a retrospective cohort study of 72 patients (147 anteroposterior pelvic radiographs) between January 2004 and December 2016. Center-edge angle (CEA) of Wiberg, acetabular index (AI), and neck-shaft angle (NSA) were measures in all hips. The relationship between radiographic and demographic parameters of age, sex, and body mass index z-score (BMIzs) were assessed. RESULTS: A total of 274 radiographic measurements were performed and analyzed in 72 patients. The mean CEA, AI, and NSA were 21.8±7.1 degrees (range, 5 to 35 degrees), 16.7±7 degrees (range, 5 to 45 degrees), and 142±8.5 degrees (range, 128 to 165 degrees), respectively. HD was diagnosed in 79 (29%) hip radiographs and varied significantly between the age groups (P<0.01). A statistically significant association was identified between age and CEA [ß coef, 0.80; 95% confidence interval (CI), 0.6-1; P<0.01], AI (ß coef, -0.90; 95% CI, -1.1 to -0.7; P<0.01), and NSA (ß coef, -1.11; 95% CI, -1.4 to -0.9; P<0.01) angles. Sex and BMIzs were not identified as independent predictors of radiographic hip angles (P>0.1). CONCLUSIONS: The present study demonstrated favorable evolution of hip radiographic parameters in the PWS population treated with growth hormone early in development. This finding should prompt orthopedists to consider observation alone in the management algorithm for HD in patients with PWS. LEVELS OF EVIDENCE: Level III-a retrospective comparative study.

Sensory innervation of the human elbow joint and surgical considerations.

Based on the currently available literature, total denervation of the elbow joint is considered impossible. However, consensus with respect to the anatomic location of sensory branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches innervating the elbow joint, as well as the distribution of sensory receptors about its capsule. Four electronic databases were queried, between January 1945 and June 2019. Twenty-one original articles providing a detailed description of the distribution of sensory receptors about the elbow joint capsule (5) and its articular branches (16) were reviewed. The posterior capsule was found to be primarily innervated by the ulnar and radial nerves via combined articular branches and sensory branches of the medial antebrachial cutaneous nerve. The anterior capsule was found to be primarily innervated by a plexus of articular ramifications from muscular branches of mixed nerves (ulnar, musculocutaneous, radial, and median nerves). A higher density of nociceptors and mechano-receptors was identified within the posterior and anterior capsules, respectively. Thorough denervation, via the technique proposed herein, is likely to be sufficient in eliminating pain from degenerative conditions of the elbow joint.

Periprosthetic joint infection in aseptic total hip arthroplasty revision.

PURPOSE: There is no consensus regarding systematic screening for infection in aseptic revision total hip arthroplasty (THA). The rationale for systematic intra-operative samples is to increase the sensitivity of latent infections detection, which may require specific treatment. However, the incidence of occult infection in revision THAs is not precisely known. As such, the aim of the study was to evaluate the incidence of occult infection in presumed aseptic revision THAs and identify associated risk factors. METHOD: Bacteriological samples from 523 aseptic THA revisions performed for five years were analyzed. Revisions performed for periprosthetic joint infection (PJI) or clinical suspicion of PJI were excluded. Microbiological cultures were performed using tissue samples in 505 cases (97%), synovial fluid in blood culture vials in 158 (30%), and in dry tubes in 263 (50%). Implants were sent for sonication in 12 cases (2.6%). The mean number of microbiological samples per patient was 3.6 (range, 1-15). Histology samples were collected for 300 patients (57%). RESULTS: The incidence of occult infection was 7% (36 cases) and contamination 8% (42 cases). Among occult infections, the primary reasons for revision were dislocation (42%), aseptic loosening (25%), fracture (19%), and others (14%). The infection rate in the dislocation group was significantly higher than that of other reasons for revision (p < 0.001). Among the patients determined with PJI, the revision THA was performed less than a year after primary in 19 (53%). CONCLUSION: The incidence of occult PJI justifies systematic intraoperative sampling. A short time between primary arthroplasty and revision or an early postoperative dislocation is a factor to suspect infections.

Ultrasound-Guided Versus Landmark-Based Approach to the Distal Suprascapular Nerve Block: A Comparative Cadaveric Study.

PURPOSE: To compare the accuracy of distal suprascapular nerve (dSSN) blockade performed with the use of ultrasound-guided regional anesthesia (USRA) versus with a landmark-based approach (LBA). A secondary aim was to describe the anatomic features of the sensory branches of the dSSN. METHODS: USRA and LBA were performed in 15 shoulders each from 15 cadavers (total of 30 shoulders). Then, 10 mL of methylene blue‒infused ropivacaine 0.75% was injected into the dSSN. Simultaneously, 2.5 mL of red latex solution was injected to identify the position of the needle tip. The division and distribution of the sensory branches originating from the SSN were described. RESULTS: The tip of the needle was identified at 1.3 cm (range, 0-5.2 cm) and 1.5 cm (range, 0-4.5 cm) with USRA and the LBA, respectively (P = .90). Staining diffused past the origin of the most proximal sensory branch in 27 cases. The most proximal sensory branch arose 2.5 cm from the suprascapular notch. Among the 3 failures that occurred in the USRA group, the sensory branches also failed to be marked. All 30 dSSNs gave off 3 sensory branches, which innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments. CONCLUSIONS: An LBA is as reliable and accurate as US guidance for anesthetic blockade of the dSSN. Marking of the suprascapular nerve must be proximal to the suprascapular notch to involve the 3 sensory branches in the anesthetic blockade. CLINICAL RELEVANCE: The present study demonstrates that a landmark-based approach to anesthetic blockade of the distal suprascapular nerve is accurate and can be performed by orthopaedic surgeons lacking experience in ultrasound-guided anesthetic techniques.

Molecular pathology of total knee arthroplasty instability defined by RNA-seq.

Total knee arthroplasty (TKA) is a durable and reliable procedure to alleviate pain and improve joint function. However, failures related to flexion instability sometimes occur. The goal of this study was to define biological differences between tissues from patients with and without flexion instability of the knee after TKA. Human knee joint capsule tissues were collected at the time of primary or revision TKAs and analyzed by RT-qPCR and RNA-seq, revealing novel patterns of differential gene expression between the two groups. Interestingly, genes related to collagen production and extracellular matrix (ECM) degradation were higher in samples from patients with flexion instability. Partitioned clustering analyses further emphasized differential gene expression patterns between sample types that may help guide clinical interpretations of this complication. Future efforts to disentangle the effects of physical and biological (e.g., transcriptomic modifications) risk factors will aid in further characterizing and avoiding flexion instability after TKA.