Angiogenic and Arthritogenic Properties of the Soluble Form of CD13.

Aminopeptidase N/CD13 is expressed by fibroblast-like synoviocytes (FLS) and monocytes (MNs) in inflamed human synovial tissue (ST). This study examined the role of soluble CD13 (sCD13) in angiogenesis, MN migration, phosphorylation of signaling molecules, and induction of arthritis. The contribution of sCD13 was examined in angiogenesis and MN migration using sCD13 and CD13-depleted rheumatoid arthritis (RA) synovial fluids (SFs). An enzymatically inactive mutant CD13 and intact wild-type (WT) CD13 were used to determine whether its enzymatic activity contributes to the arthritis-related functions. CD13-induced phosphorylation of signaling molecules was determined by Western blotting. The effect of sCD13 on cytokine secretion from RA ST and RA FLS was evaluated. sCD13 was injected into C57BL/6 mouse knees to assess its arthritogenicity. sCD13 induced angiogenesis and was a potent chemoattractant for MNs and U937 cells. Inhibitors of Erk1/2, Src, NF-κB, Jnk, and pertussis toxin, a G protein-coupled receptor inhibitor, decreased sCD13-stimulated chemotaxis. CD13-depleted RA SF induced significantly less MN migration than sham-depleted SF, and addition of mutant or WT CD13 to CD13-depleted RA SF equally restored MN migration. sCD13 and recombinant WT or mutant CD13 had similar effects on signaling molecule phosphorylation, indicating that the enzymatic activity of CD13 had no role in these functions. CD13 increased the expression of proinflammatory cytokines by RA FLS, and a CD13 neutralizing Ab inhibited cytokine secretion from RA ST organ culture. Mouse knee joints injected with CD13 exhibited increased circumference and proinflammatory mediator expression. These data support the concept that sCD13 plays a pivotal role in RA and acute inflammatory arthritis.

Wound Healing Complications in Diabetic Patients Undergoing Carpal Tunnel and Trigger Finger Releases: A Retrospective Cohort Study.

PURPOSE: To evaluate the association of diabetes and perioperative hemoglobin A1C (HgA1C) value with postoperative wound healing complications following carpal tunnel release (CTR) and trigger finger release (TFR). METHODS: A retrospective review of diabetic patients who underwent CTR and/or TFR between 2014 and 2018 was performed. Hemoglobin A1C value within 90 days of surgery was recorded for all diabetic patients. A nondiabetic comparison group was selected from within the same study period in an approximately 1:1 procedural ratio, although direct matching was not performed. A chart review was used to examine postoperative wound healing complications, such as wound infection, wound dehiscence, or delayed wound healing. RESULTS: Two hundred sixty-two diabetic patients and 259 nondiabetic patients underwent 335 and 337 CTR and/or TFR procedures, respectively. There were 36 wound complications in the diabetic group and 9 complications in the nondiabetic group. Logistic regression analysis demonstrated an increased association of wound healing complications with diabetic patients compared to nondiabetic patients. Additionally, an increased association was demonstrated among diabetic patients with an HgA1C value above 6.5% compared with those with an HgA1C value below 6.5%. CONCLUSIONS: Compared with nondiabetic controls, diabetic patients have increased associated risk of postoperative wound healing complications following CTR and/or TFR. This increased association was further demonstrated among diabetic patients with elevated perioperative HgA1C values. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.

Physiological Loading of the Coonrad/Morrey, Nexel, and Discovery Elbow Systems: Evaluation by Finite Element Analysis.

PURPOSE: Wear of polyethylene bearings represents a limiting factor in the long-term success of total elbow prostheses. Bearing stress is 1 factor contributing to accelerated wear. Physiological loading of total elbow prostheses and implant design influence upon bearing stresses have not been well described. This study evaluates bearing stresses in 3 commercially available implant designs under loads associated with daily living. METHODS: Motion tracking from a healthy volunteer helped establish a musculoskeletal model to simulate flexor and extensor muscle activation at 0°, 45°, and 90° of shoulder abduction with a 2.3-kg weight in hand-forces and moments were measured at the elbow. Resulting physiological joint reaction forces and moments were applied to finite element models of 3 total elbow bearing designs (Coonrad/Morrey, Nexel, and Discovery) to evaluate contact area and polyethylene stresses. RESULTS: Increasing shoulder abduction resulted in minimal changes to the elbow joint reaction force but greater joint moments. All implants showed greater peak stresses with increasing shoulder abduction-elbow varus. Discovery and Nexel achieved greater contact area (23% vs > 100%) and demonstrated up to 39% lower peak polyethylene stresses compared with the Coonrad/Morrey design. CONCLUSIONS: Shoulder abduction results in a varus moment at the elbow. Newer bearing designs (Nexel and Discovery) provide a combination of higher contact area, improved load sharing, reduced edge loading, and lower stresses through elbow range of motion when compared with a cylindrical hinge-bearing design (Coonrad/Morrey). CLINICAL RELEVANCE: Although the Coonrad/Morrey is a clinically successful prosthesis, our physiological loading model shows that Discovery and Nexel provide greater contact area, better load sharing and lower peak stresses. This may lead to a decrease in polyethylene wear rates and the eventual risks of osteolysis and aseptic loosening. Further studies are needed to determine how these findings translate clinically.

Proximal Pole Scaphoid Nonunion Reconstruction With 1,2 Intercompartmental Supraretinacular Artery Vascularized Graft and Compression Screw Fixation.

PURPOSE: To review the incidence of union of patients with proximal pole scaphoid fracture nonunions treated using a 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) vascularized graft and a small compression screw. METHODS: This is a retrospective case series of 12 patients. Calculations of the size of the proximal pole fragment relative to the total scaphoid were performed using posteroanterior view scaphoid radiographs with the wrist in ulnar deviation and flat on the cassette. Analyses were repeated 3 times per subject, and the average ratio of proximal pole fragment relative to the entire scaphoid was calculated. We reviewed medical records, radiographs, and computed tomography (CT) scans of these 12 patients. The CT scans that were performed after an average of 12 weeks were ultimately used to confirm union of the scaphoid fractures. One patient was unable to have a CT so was excluded from the final calculation. RESULTS: All 11 (100%) scaphoid fractures that were assessed by CT were found to be healed at the 12-week assessment point. The mean proximal pole fragment size was 18% (range, 7%-27%) of the entire scaphoid. CONCLUSIONS: The 1,2 ICSRA vascularized graft and compression screw was an effective treatment for patients with proximal pole scaphoid fractures. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Return to Play After Osteochondral Autograft Transplantation of the Capitellum: A Systematic Review.

PURPOSE: To determine the rate of return to play and to identify lesion or osteochondral graft characteristics that may influence the return to competitive athletics after osteochondral autograft transplantation (OAT) for symptomatic osteochondritis dissecans (OCD) lesions. METHODS: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A duplicate search of PubMed, Embase, Scopus, Web of Science, and CENTRAL databases was performed, beginning from the database inception dates through July 2016, for all articles evaluating the return to play after OAT for OCD lesions of the capitellum. A methodological quality assessment was completed for all included studies. Patient demographics, osteochondral lesion and graft characteristics, the number of patients, and timing of return to competitive activity were collected and evaluated. Association between graft size/number, the time to osseous healing, and return to sport was evaluated. RESULTS: Seven articles met the inclusion criteria. All included studies were case series of moderate quality with a mean Methodological Index for Non-Randomized Studies score of 12/16. Overall, 94% (119/126) of patients undergoing OAT for OCD lesions of the capitellum successfully returned to competitive sports. The mean reported time for unrestricted return to athletic competition after OAT was 5.6 months (range, 3-14 months). CONCLUSIONS: Current best evidence suggests that OAT is successful in treating advanced OCD lesions of the capitellum and returning athletes to high-level competition. Evidence supporting the association between the size and number of grafts used and the time to osseous healing and return to sport is currently limited. Our assessment of the time to return to athletic competition was limited because of variable surgical technique, postoperative rehabilitation protocols, and outcome assessment. LEVEL OF EVIDENCE: Level IV, systematic review of Level IV studies.

Comparison of 2-Dimensional and 3-Dimensional Metacarpal Fracture Plating Constructs Under Cyclic Loading.

PURPOSE: Metacarpal fractures are commonly treated by a variety of means including casting or open reduction internal fixation when unacceptable alignment is present following attempted closed reduction. Dorsal plating with either single-row 2-dimensional or double-row 3-dimensional plates has been proposed. This study's purpose was to determine if there are any differences in fixation construct stability under cyclic loading and subsequent load to failure between the lower profile 3-dimensional and the larger 2-dimensional plates in a metacarpal fracture gap sawbone model. METHODS: Thirty metacarpal cortico-cancellous synthetic bones were cut with a 1.75-mm gap between the 2 fragments simulating mid-diaphyseal fracture comminution. Half of the metacarpals were plated with 2.0-mm locking 2-dimensional plates and half with 1.5-mm locking 3-dimensional plates. The plated metacarpals were mounted into a materials testing apparatus and cyclically loaded under cantilever bending for 2,000 cycles at 70 N, then 2,000 cycles at 120 N, and finally monotonically loaded to failure. Throughout testing, fracture gap sizes were measured, failure modes were recorded, and construct strength and stiffness values were calculated. RESULTS: All 3-dimensional constructs survived both cyclic loading conditions. Ten (67%) 2-dimensional constructs survived both loading conditions, whereas 5 (33%) failed the 120-N loading at 1377 ± 363 cycles. When loaded to failure, the 3-dimensional constructs failed at 265 N ± 21 N, whereas the 2-dimensional constructs surviving cyclic loading failed at 190 N ± 17 N. CONCLUSIONS: The shorter, thinner 3-dimensional metacarpal plates demonstrated increased resistance to failure in a cyclic loading model and increased load to failure compared with the relatively longer, thicker 2-dimensional metacarpal plates. CLINICAL RELEVANCE: The lower-profile 3-dimensional metacarpal plate fixation demonstrated greater stability for early postoperative resistance than the thicker 2-dimensional fixation, whereas the smaller size and lower profile of the 3-dimensional plates potentially reduces soft tissue stripping, implant prominence, and risk of extensor tendon irritation.

Predictors of functional outcomes after simple decompression for ulnar neuropathy at the elbow: a multicenter study by the SUN study group.

OBJECTIVE: To identify predictors of surgical outcome for ulnar neuropathy at the elbow (UNE). DESIGN: Prospective cohort followed for 1 year. SETTING: Clinics. PARTICIPANTS: Patients diagnosed with UNE (N=55). INTERVENTION: All subjects had simple decompression surgery. MAIN OUTCOME MEASURES: The primary outcome measure was patient-reported outcomes, such as overall hand function through the Michigan Hand Outcomes Questionnaire (MHQ). Predictors included age, duration of symptoms, disease severity, and motor conduction velocity across the elbow. RESULTS: Multiple regression models with change in the overall MHQ score as the dependent variable showed that at 3 months postoperative time, patients with <3 months duration of symptoms showed 12 points (95% confidence interval [CI], 0.9-23.5) greater improvement in MHQ scores than those with ≥3 months symptom duration. Less than 3 months of symptoms was again associated with 13 points (95% CI, 2.9-24) greater improvement in MHQ scores at 6 months postoperative, but it was no longer associated with better outcomes at 12 months. A worse baseline MHQ score was associated with significant improvement in MHQ scores at 3 months (coefficient, -0.38; 95% CI, -.67 to -.09), and baseline MHQ score was the only significant predictor of 12 month MHQ scores (coefficient, -.40; 95% CI, -.79 to -.01). CONCLUSIONS: Subjects with <3 months of symptoms and worse baseline MHQ scores showed significantly greater improvement in functional outcomes as reported by the MHQ. However, duration of symptoms was only predictive at 3 or 6 months because most patients recovered within 3 to 6 months after surgery.

Arcus venosus dorsalis pedis: morphological considerations for use in superficial palmar arch reconstruction.

PURPOSE: To report the branching patterns, vessel diameters, and location of the valves in the arcus venosus dorsalis pedis (AVDP) as a graft option for use in superficial palmar arch reconstruction after mutilating hand injuries. METHODS: We dissected 10 cadaveric feet and measured vessel diameters, recorded number of branches, and located valves within the tibial, middle, and fibular thirds of the system. We used retrograde india ink injection to locate valves. RESULTS: The AVDP branching pattern was grossly different from side to side in the 4 cadavers with bilateral feet available. Mean flat diameters were 4.7, 2.9, and 2.1 mm in the tibial, middle, and fibular thirds of the arch, respectively. There was a mean of 1.7 valves (range, 1-4 valves) in the tibial third, 1.5 valves (range 0-4 valves) in the middle third, and 0 valves in the fibular third. There was an average of 3.4 branches off the middle third with a mean branch diameter of 2.1 mm. In 65% of these branches, valves were within 1 cm distal to the main arch. The direction of flow within the middle third was from fibular to tibial. CONCLUSIONS: Valves were commonly found within the middle and tibial thirds of the AVDP and within branches just distal to bifurcations. By contrast, the fibular third of the AVDP contained no valves. Valvular anatomy suggests that the direction of flow within the middle third was from fibular to tibial direction. CLINICAL RELEVANCE: The AVDP is morphologically similar to the palmar arch. When rendering valves within the AVDP incompetent, attention should be paid not just to the main arch itself, but also to branches off the AVDP. The fibular and middle thirds of the AVDP can safely be used for palmar arch reconstruction without blockage of flow owing to valves. The branches off the middle third must be used within a few millimeters of their takeoff to avoid valves.

Digital artery flow hemodynamics: An ultrasonographic study.

BACKGROUND: There is a lack of data regarding the baseline hemodynamic blood flow parameters of the wrist and digits. Therefore, we aimed to quantify the digital and radial artery blood flow parameters using ultrasound and assess the influence of patient characteristics on hemodynamics. METHODS: We analyzed ultrasonographic data from 25 patients (50 hands) between October 2019 and December 2021. Variables of interest included dimensions of the radial artery and index finger (IF) ulnar and radial digital arteries at the palmodigital crease and their corresponding flow parameters. We compared variables among men and women and patients with and without diabetes using Wilcoxon Rank Sum test. RESULTS: Our cohort consisted of 18 women (36 hands) and three participants with diabetes (six hands). The mean diameter of the IF radial digital artery was 7 mm, and that of the ulnar digital artery was 10 mm. The average peak systolic velocity for the radial digital artery was 21.31 cm/sec, and for the ulnar digital artery, it was 30.03 cm/sec. Comparing men and women, the only significant difference found was in the time-averaged mean velocity for the ulnar digital artery (men:5.66 cm/sec vs. women:9.68 cm/sec, P = 0.02) and volume of flow for the ulnar digital artery (men:10.87cc/min vs. women:18.58cc/min, P = 0.03). We found no differences in blood flow parameters comparing participants with and without diabetes. CONCLUSION: These data provide a baseline measurement of digital flow hemodynamics that can be used in future studies to model vascular flow after replantation.

Utilization, Complications, and Costs of Inpatient versus Outpatient Total Elbow Arthroplasty.

BACKGROUND: Although total hip and knee arthroplasty have largely moved to the outpatient setting, total elbow arthroplasty (TEA) remains a predominantly inpatient procedure. Currently, evidence on the safety and potential cost savings of outpatient TEA is limited. Therefore, we aimed to compare the costs and complications associated with performing TEA in the inpatient versus outpatient setting. METHODS: We identified patients who received elective TEA using the Truven Health MarketScan database. Outcomes of interest were 90-day complication rate, readmission rate, and procedure costs in the inpatient and outpatient settings. We used propensity score matching and logistic regression analysis to assess how patient comorbidities and surgical setting influenced complications and readmission rates. The median cost per patient was compared using the Mann-Whitney U test. RESULTS: We identified 307 outpatient and 414 inpatient TEA procedures over a 9-year period. Elixhauser comorbidity scores were higher for the inpatient cohort. The incidence of surgical complications was significantly higher in the inpatient than the outpatient cohort (27% vs 9%). The odds of 90-day readmissions were similar in the 2 groups (37% vs 25%). In terms of cost, the median inpatient TEA was more expensive than outpatient TEA ($26 817 vs $18 412). However, the median cost for occupational therapy within 90 days of surgery was higher for outpatient TEA patients ($687 vs $571). CONCLUSIONS: The results of this study demonstrate that surgeons can consider a transition toward outpatient TEA for patients without significant comorbidities, as this will substantially reduce health care costs.

Coronal shear fractures of the distal humerus.

Management of coronal shear fractures of the distal humerus has evolved considerably over the past 3 decades, with an increased appreciation of the complexity of these fractures, improvements in internal fixation techniques, and the use of more extensile exposures. Nearly all of these fractures are displaced, given the paucity of soft tissue attachments and correspondingly, nonsurgical management is fraught with complications including chronic pain, mechanical symptoms, and instability and is not recommended. Good to excellent outcomes can be achieved in the majority of patients with open reduction internal fixation, particularly when the fracture is limited to the radiocapitellar joint. Outcomes are worst for those with considerable medial extension or comminution. Computed tomography is highly recommended to guide surgical planning. The presence of posterior comminution or extension to the medial column might require more extensile exposures and supplemental fixation for adequate stability. Arthroscopic reduction and fixation techniques have been described for the simple fracture. Those not amenable to fixation might do better with total elbow arthroplasty in a select population. Long-term data demonstrate the durability of these elbows following open reduction internal fixation. Complications other than stiffness are rare. Radiographic avascular necrosis does not appear to affect outcome. Radiographic mild to moderate arthritis was observed in half of patients at 17-year follow-up.

Biomechanical properties of fixed-angle volar distal radius plates under dynamic loading.

PURPOSE: To evaluate and compare the biomechanical properties of 8 different locked fixed-angle volar distal radius plates under conditions designed to reflect forces seen in early fracture healing and postoperative rehabilitation. METHODS: We evaluated the Acumed Acu-Loc (Acumed, Hillsboro, OR), Hand Innovations DVR (Hand Innovations, Miami, FL), SBi SCS volar distal radial plate (Small Bone Innovations, Morrisville, PA), Synthes volar distal radius plate and EA extra-articular volar distal radius plate (Synthes, Paoli, PA), Stryker Matrix-SmartLock (Stryker Leibinger, Kalamazoo, MI), Wright Medical Technology Locon VLS (Wright Medical Technology, Arlington, TN), and Zimmer periarticular distal radius locking plate (Zimmer, Warsaw, IN). After affixing each plate to a synthetic corticocancellous radius, we created a standardized dorsal wedge osteotomy. Each construct had cyclic loading of 100 N, 200 N, and 300 N for a total of 6000 cycles. Outcomes, including load deformation curves, displacement, and ultimate yield strengths, were collected for each construct. RESULTS: The Wright plate was significantly stiffer at the 100 N load than the Zimmer plate and was stiffer at the 300 N load than 4 other plates. The Zimmer and Hand Innovations plates had the highest yield strengths and significantly higher yield strengths than the Wright, SBi, Stryker, and Synthes EA plates. CONCLUSIONS: Given the biomechanical properties of the plates tested, in light of the loads transmitted across the native wrist, all plate constructs met the anticipated demands. It seems clear that fracture configuration, screw placement, cost, and surgeon familiarity with instrumentation should take priority in selecting a plating system for distal radius fracture treatment. CLINICAL RELEVANCE: This study provides further information to surgeons regarding the relative strengths of different plate options for the treatment of distal radius fractures.

Soluble CD13 induces inflammatory arthritis by activating the bradykinin receptor B1.

CD13, an ectoenzyme on myeloid and stromal cells, also circulates as a shed, soluble protein (sCD13) with powerful chemoattractant, angiogenic, and arthritogenic properties, which require engagement of a G protein-coupled receptor (GPCR). Here we identify the GPCR that mediates sCD13 arthritogenic actions as the bradykinin receptor B1 (B1R). Immunofluorescence and immunoblotting verified high expression of B1R in rheumatoid arthritis (RA) synovial tissue and fibroblast-like synoviocytes (FLSs), and demonstrated binding of sCD13 to B1R. Chemotaxis, and phosphorylation of Erk1/2, induced by sCD13, were inhibited by B1R antagonists. In ex vivo RA synovial tissue organ cultures, a B1R antagonist reduced secretion of inflammatory cytokines. Several mouse arthritis models, including serum transfer, antigen-induced, and local innate immune stimulation arthritis models, were attenuated in Cd13-/- and B1R-/- mice and were alleviated by B1R antagonism. These results establish a CD13/B1R axis in the pathogenesis of inflammatory arthritis and identify B1R as a compelling therapeutic target in RA and potentially other inflammatory diseases.

Distal biceps tendon reconstruction with tendoachilles allograft: a modification of the endobutton technique utilizing an ACL reconstruction system.

Distal biceps tendon ruptures typically occur with biceps contraction against resistance with the elbow flexed at 90 degrees. Anatomic repair is the gold standard in active patients. Numerous surgical techniques are available; however, the Endobutton might offer several advantages. We describe a novel technique for chronic distal biceps reconstruction using a modification of the Endobutton technique with an anterior cruciate ligament (ACL) drill guide as well as tendoachilles allograft. The Endobutton technique might offer several advantages, including direct tendon-to-bone healing, less bony debris to limit heterotopic ossification, less heating of the bone, ease of use, a biomechanical superiority, and excellent clinical outcomes.

Prevention and treatment of elbow stiffness.

The elbow is as prone to stiffness as it is essential for upper-extremity function. The elbow is a highly constrained synovial hinge joint that frequently becomes stiff after injury. Elbow contracture is challenging to treat, and therefore prevention is of paramount importance. When this approach fails, nonoperative followed by operative treatment modalities can be pursued. In the future, efforts to prevent and treat elbow stiffness may target the basic science mechanisms involved.

Citrullinated Inhibitor of DNA Binding 1 Is a Novel Autoantigen in Rheumatoid Arthritis.

OBJECTIVE: To explore the intrinsic role of inhibitor of DNA binding 1 (ID-1) in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) and to investigate whether ID-1 is citrullinated and autoantigenic in RA. METHODS: RA patient serum ID-1 levels were measured before and after infliximab treatment. RA FLS were transfected with a clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 construct targeting ID-1 to examine the effects of ID-1 deletion. RA synovial fluid (SF) and homogenized synovial tissue (ST) were immunoprecipitated for ID-1 and measured for citrullinated residues using an enzyme-linked immunosorbent assay and Western blotting. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed on in vitro-citrullinated recombinant human ID-1 (cit-ID-1) to localize the sites of citrullination. Normal and RA sera and SF were analyzed by immunodot blotting for anti-citrullinated protein antibodies (ACPAs) to cit-ID-1. RESULTS: RA patient serum ID-1 levels positively correlated with several disease parameters and were reduced after infliximab treatment. RA FLS displayed reduced growth and a robust increase in interleukin-6 (IL-6) and IL-8 production upon deletion of ID-1. ID-1 immunodepletion significantly reduced the levels of citrullinated residues in RA SF, and citrullinated ID-1 was detected in homogenized RA ST (n = 5 samples; P < 0.05). Immunodot blot analyses revealed ACPAs to cit-ID-1 but not to native ID-1, in RA peripheral blood (PB) sera (n = 30 samples; P < 0.001) and SF (n = 18 samples; P < 0.05) but not in normal PB sera. Following analyses of LC-MS/MS results for citrullination sites and corresponding reactivity in immunodot assays, we determined the critical arginines in ID-1 for autoantigenicity: R33, R52, and R121. CONCLUSION: Novel roles of ID-1 in RA include regulation of FLS proliferation and cytokine secretion as well as autoantigenicity following citrullination.

Biomechanics of the Proximal Radius Following Drilling of the Bicipital Tuberosity to Mimic Cortical Button Distal Biceps Repair Technique.

BACKGROUND: A fracture through the proximal radius is a theoretical concern after cortical button distal biceps fixation in an active patient. The permanent, nonossified cortical defect and medullary tunnel is at risk during a fall eliciting rotational and compressive forces. We hypothesized that during simulated torsion and compression, in comparison with unaltered specimens, the cortical button distal biceps repair model would have decreased torsional and compressive strength and would fracture in the vicinity of the bicipital tuberosity bone tunnel. METHODS: Sixteen fourth-generation composite radius Sawbones models were used in this controlled laboratory study. A bone tunnel was created through the bicipital tuberosity to mimic the exact bone tunnel, 8 mm near cortex and 3.2 mm far cortex, made for the BicepsButton distal biceps tendon repair. The radius was then prepared and mounted on either a torsional or compression testing device and compared with undrilled control specimens. RESULTS: Compression tests resulted in average failure loads of 9015.2 N in controls versus 8253.25 N in drilled specimens ( P = .074). Torsional testing resulted in an average failure torque of 27.3 Nm in controls and 19.3 Nm in drilled specimens ( P = .024). Average fracture angle was 35.1° in controls versus 21.1° in drilled. Gross fracture patterns were similar in compression testing; however, in torsional testing all fractures occurred through the bone tunnel in the drilled group. CONCLUSION: There are weaknesses in the vicinity of the bone tunnel in the proximal radius during biomechanical stress testing which may not be clinically relevant in nature. CLINICAL RELEVANCE: In cortical button fixation, distal biceps repairs creates a permanent, nonossified cortical defect with tendon interposed in the bone tunnel, which can alter the biomechanical properties of the proximal radius during compressive and torsional loading.

The Effect of Axial Loading on Ulnar Variance.

Background Forearm rotation results in change in ulnar variance. Axial loading of the wrist is required to maintain daily activities. Change in ulnar variance during axial loading has not been investigated previously. Purpose To measure the change in ulnar variance on axially loaded wrists. Patients and Methods We examined 21 asymptomatic individuals and 24 patients with unilateral ulnar-sided wrist pain. All patients underwent standard neutral posteroanterior wrist radiographs without load and under axial loading on bilateral wrists. Axial loading was standardized at 18.1 kgf using an analog weight scale. A magnetic resonance (MR) arthrogram was obtained only in patients with ulnar-sided wrist pain. Beighton flexibility score was recorded on healthy volunteers. Change in ulnar variance between 0 and 18.1 kgf was compared for each wrist among all subjects. A correlation was sought between the change in ulnar variance, MR arthrogram findings, and physical examination. Results In individuals without wrist pain, on average, 0.4 mm increase in ulnar variance was measured between 0 and 18.1 kgf. There was no difference between the dominant and nondominant side. No correlation was found with increasing age. In contrast, patients with ulnar-sided wrist pain displayed an average increase of 0.8 mm in ulnar variance. Compared with the contralateral wrist, more than 1 mm increase in ulnar variance was correlated with intra-articular pathologies including dorsoulnar ligament disruption, central triangular fibrocartilage complex (TFCC) perforation, and foveal detachment. Conclusion Compared with contralateral side, more than 1 mm increase in ulnar variance is suggestive of longitudinal instability or TFCC pathology. Level of Evidence Level II, diagnostic.

Anatomic considerations regarding the posterior interosseous nerve at the elbow.

The relationship of the posterior interosseous nerve (PIN) to the radius was studied to determine the change in position associated with forearm motion because of the risk of injury during surgical exposure of the lateral elbow. The distance from the PIN to the radiocapitellar joint (RCJ) was measured in 24 cadaveric specimens in pronation, neutral rotation, and supination. The mean distance from the PIN to the RCJ was 4.6 +/- 0.5 cm, 5.3 +/- 0.6 cm, and 5.7 +/- 0.7 cm in supination, neutral rotation, and pronation, respectively. In pronation, there was substantial variation of this distance, with a minimum distance of 4.3 cm. In supination, the minimum distance was 4.0 cm. On the basis of limited PIN distal translation, noted with pronation, as well as the variation between individuals, we recommend limiting dissection to 4.0 cm from the RCJ during a lateral approach without formal identification of the PIN. This safe zone is recommended regardless of forearm rotation, in contrast to the recommendation of prior authors, as pronation does not reliably increase the distance of the PIN to the RCJ.

Immobilization for scaphoid fracture: forearm rotation in long arm thumb-spica versus Munster thumb-spica casts.

A Munster thumb-spica cast may play a role in the conservative treatment of non-displaced scaphoid fractures by allowing some elbow motion during the long immobilization period.