Diagnosis and treatment of posterior shoulder instability based on the ABC classification.

Posterior shoulder instability (PSI) is less common than anterior shoulder instability, accounting for 2-12% of total shoulder instability cases. However, a much higher frequency of PSI has been recently indicated, suggesting that PSI accounts for up to 24% of all young and active patients who are surgically treated for shoulder instability. This differentiation might be explained due to the frequent misinterpretation of vague symptoms, as PSI does not necessarily present as a recurrent posterior instability event, but often also as mere shoulder pain during exertion, limited range of motion, or even as yet asymptomatic concomitant finding. In order to optimize current treatment, it is crucial to identify the various clinical presentations and often unspecific symptoms of PSI, ascertain the causal instability mechanism, and accurately diagnose the subgroup of PSI. This review should guide the reader to correctly identify PSI, providing diagnostic criteria and treatment strategies.

The importance of interdigitating screw fixation of the trochlea in double plate osteosynthesis of low transcondylar distal humerus fractures: A biomechanical study.

OBJECTIVE: The trochlea is of great importance for the stability of the elbow and its fixation in low transcondylar fractures of the distal humerus is especially challenging. The aim of this study was to determine the optimal trochlea fixation in double plate osteosynthesis of intraarticular distal humerus fractures. METHODS: A low transcondylar, C3-type distal humerus fracture was created in 20 fresh-frozen human cadaveric humeri. The samples were then randomly divided into two groups of 10 specimens each. Double plate osteosynthesis was performed in both groups. In group A, the two most distal screws of the lateral plate were inserted into the trochlea fragment. In group B, these screws did not extend into the trochlea. Displacement under cyclic loading and ultimate failure loads were determined for all specimens. RESULTS: Group A showed significantly less displacement under cyclic loading in each measurement interval (0.92 mm vs. 1.53 mm after 100 cycles, p = 0 0.006; 1.10 mm vs. 1.84 mm after 1000 cycles, p = 0.007; 1.18 mm vs. 1.98 mm after 2000 cycles, p = 0.008). The ultimate failure load was significantly higher in group A than in group B (345.61 ± 120.389 N vs. 238.42 ± 131.61 N, p = 0.037). CONCLUSIONS: Fixation of the trochlea with interdigitating screws in double plate osteosynthesis of low-condylar type C distal humerus fractures results in superior construct stability. LEVEL OF EVIDENCE: not applicable (biomechanical).

Treatment strategies for simple elbow dislocation - a systematic review.

BACKGROUND: Current treatment concepts for simple elbow dislocation involve conservative and surgical approaches. The aim of this systematic review was to identify the superiority of one treatment strategy over the other by a qualitative analysis in adult patients who suffered simple elbow luxation. STUDY DESIGN: A systematic review in accordance with the PRISMA guidelines and following the suggestions for reporting on qualitative summaries was performed. A literature search was conducted using PubMed and Scopus, including variations and combinations of the following keywords: elbow, radiohumeral, ulnohumeral, radioulnar, luxation, and therapy. Seventeen studies that performed a randomized controlled trial to compare treatment strategies as conservative or surgical procedures were included. Reviews are not selected for further qualitative analysis. The following outcome parameters were compared: range of motion (ROM), Mayo Elbow Performance Score (MEPS), Disabilities of the Arm, Shoulder and Hand outcome measure (Quick-DASH), recurrent instability, pain measured by visual analog scale (VAS) and time to return to work (RW). RESULTS: Early mobilization after conservative treatment strategies showed improved ROM compared to immobilization for up to 3 weeks after surgery with less extension deficit in the early mobilization group (16° ± 13°. vs. 19.5° ± 3°, p < 0.05), as well as excellent clinical outcome scores. Surgical approaches showed similar results compared to conservative treatment, leading to improved ROM (115 vs. 118 ± 2.8) and MEPS: 95 ± 7 vs. 92 ± 4. CONCLUSION: Conservative treatment with early functional training of the elbow remains the first-line therapy for simple elbow dislocation. The surgical procedure provides similar outcomes compared to conservative treatment regarding MEPS and ROM for patients with slight initial instability in physical examination and radiographs. People with red flags for persistent instability, such as severe bilateral ligament injuries and moderate to severe instability during initial physical examination, should be considered for a primary surgical approach to prevent recurrent posterolateral and valgus instability. Postoperative early mobilization and early mobilization for conservatively treated patients is beneficial to improve patient outcome and ROM.

[Treatment of osteochondritis dissecans]. / Therapie der Osteochondrosis dissecans.

Osteochondritis dissecans (OD) is a rare condition with an incidence of 30/100,000. It especially affects male patients aged 10-20 years old. During the staged progression the osteochondral fragments can detach from their base. These can damage the adjacent articular cartilage, which can lead to premature osteoarthritis. Most commonly affected are the knee, ankle and elbow joints. The exact pathogenesis of OD has so far not been clearly confirmed. Several risk factors that can lead to the development of OD are discussed. These include repeated microtrauma and vascularization disorders that can lead to ischemia of the subchondral bone and to a separation of the fragments close to the joint and therefore to the development of free joint bodies. For an adequate clarification patients should undergo a thorough radiological evaluation including X­ray imaging followed by magnetic resonance imaging (MRI) to assess the integrity of the cartilage-bone formation with determination of the OD stage. The assessment is based on criteria of the International Cartilage Repair Society (ICRS). The instability of the cartilage-bone fragment increases with higher stages. Stages I and II with stable cartilage-bone interconnection can be treated conservatively. For stages III and IV, i.e., instability of the OD fragment or the presence of free fragments, surgical treatment should be performed. Primarily, refixation of a free joint body should be carried out depending on the size and vitality of the fragment. In cases of unsuccessful conservative treatment or fixation, a debridement, if necessary in combination with a bone marrow stimulating procedure, can be employed corresponding to the size of the defect. For larger cartilage defects, an osteochondral graft transplantation should be considered. Overall, OD lesions in stages I and II show a good healing tendency under conservative treatment. In cases of incipient unstable OD, refixation can also lead to good clinical and radiological results.

Partial ruptures of the distal triceps tendons show only slightly lower ultimate load to failure: a biomechanical study.

OBJECTIVE: Partial ruptures of the distal triceps tendon are usually treated surgically from a size of > 50% tendon involvement. The aim of this study was to compare the ultimate load to failure of intact triceps tendons with partially ruptured tendons and describe the rupture mechanism. METHODS: Eighteen human fresh-frozen cadaveric elbow specimens were randomly assigned to two groups with either an intact distal triceps tendon or with a simulated partial rupture of 50% of the tendon. A continuous traction on the distal triceps tendon was applied to provoke a complete tendon rupture. The maximum required ultimate load to failure of the tendon in N was measured. In addition, video recordings of the ruptures of the intact tendons were performed and analysed by two independent investigators. RESULTS: A median ultimate load to failure of 1,390 N (range Q0.25-Q0.75, 954 - 2,360) was measured in intact distal triceps tendons. The median ultimate load to failure of the partially ruptured tendons was 1,330 N (range Q0.25-Q0.75, 1,130 - 1.470 N). The differences were not significant. All recorded ruptures began in the superficial tendon portion, and seven out of nine tendons in the lateral tendon portion. DISCUSSION: Partial ruptures of the distal triceps tendon demonstrate a not statistically significant lower ultimate load to failure than intact tendons and typically occur in the superficial, lateral portion of the tendon. This finding can be helpful when deciding between surgical and conservative therapy for partial ruptures of the distal triceps tendon.

Validation of a novel 3-dimensional classification for degenerative arthritis of the shoulder.

INTRODUCTION: A novel three-dimensional classification to comprehensively describe degenerative arthritis of the shoulder (DAS) was recently published by our group. The purpose of the present work was to investigate intra- and interobserver agreement as well as validity for the three-dimensional classification. MATERIALS AND METHODS: Preoperative computed tomography (CT) scans of 100 patients who had undergone shoulder arthroplasty for DAS were randomly selected. Four observers independently classified the CT scans twice, with an interval of 4 weeks, after prior three-dimensional reconstruction of the scapula plane using a clinical image viewing software. Shoulders were classified according to biplanar humeroscapular alignment as posterior, centered or anterior (> 20% posterior, centered, > 5% anterior subluxation of humeral head radius) and superior, centered or inferior (> 5% inferior, centered, > 20% superior subluxation of humeral head radius). Glenoid erosion was graded 1-3. Gold-standard values based on precise measurements from the primary study were used for validity calculations. Observers timed themselves during classification. Cohen's weighted κ was employed for agreement analysis. RESULTS: Intraobserver agreement was substantial (κ = 0.71). Interobserver agreement was moderate with a mean κ of 0.46. When the additional descriptors extra-posterior and extra-superior were included, agreement did not change substantially (κ = 0.44). When agreement for biplanar alignment alone was analyzed, κ was 0.55. The validity analysis reached moderate agreement (κ = 0.48). Observers took on average 2 min and 47 s (range 45 s to 4 min and 1 s) per CT for classification. CONCLUSIONS: The three-dimensional classification for DAS is valid. Despite being more comprehensive, the classification shows intra- and interobserver agreement comparable to previously established classifications for DAS. Being quantifiable, this has potential for improvement with automated algorithm-based software analysis in the future. The classification can be applied in under 5 min and thus can be used in clinical practice.

[Blood flow restriction training as a treatment option for lateral elbow tendinopathy-a study presentation]. / Blood-flow-restriction-Training als Behandlungsoption der Epicondylopathia humeri radialis ­ eine Studienvorstellung.

Blood flow restriction training, developed in 1966 in Japan, is a training modality that utilizes partial arterial and complete venous blood flow occlusion. Combined with low load resistance training, it aims to induce hypertrophy and strength gains. This makes it particularly suitable for people recovering from injury or surgery, for whom the use of high training loads is unfeasible. In this article, the mechanism behind blood flow restriction training and its applicability for the treatment of lateral elbow tendinopathy is explained. An ongoing prospective, randomized, controlled trial on the treatment of lateral elbow tendinopathy is presented.

[Arthroscopic debridement of the extensor carpi radialis brevis]. / Arthroskopisches Débridement bei lateraler Epikondylitis.

Surgical treatment of lateral epicondylitis is reserved for patients who, despite extensive conservative therapy, do not experience satisfactory relief of symptoms. As an alternative to the open procedure, arthroscopic debridement of the extensor carpi radialis brevis (ECRB) muscle is a simple and standardized procedure. The arthroscopic approach also enables the additional treatment of intra-articular pathologies such as loose bodies or osteochondral lesions. After diagnostic arthroscopy, the attachment of the ECRB is visualized via the anteromedial portal, so that under visual control the debridement of the tendon fibers of the ECRB and its bony insertion site can be performed via the anterolateral portal. Postoperatively, there is no restriction of movement of the elbow joint. The outcome after arthroscopic ECRB debridement described in the literature is equivalent to that of other surgical techniques.

Patient satisfaction, joint stability and return to sports following simple elbow dislocations: surgical versus non-surgical treatment.

PURPOSE: While conservative management is commonly promoted for simple elbow dislocations, the importance of primary surgical treatment in these injuries is still undetermined. The objective of this study was to report patient-reported outcome measures (PROMs), return to sports (RTS) and joint stability using ultrasound in patients following conservative or surgical treatment after simple elbow dislocation. METHODS: Patients with a minimum follow-up of 24 months after conservative (CT) or surgical treatment (ST) following simple elbow dislocation were included in this retrospective study. To evaluate patients' postoperative outcome and satisfaction, the Elbow Self-Assessment Score (ESAS) was used, and validated scores such as the Mayo elbow performance score (MEPS), the Quick Disability of Arm and Shoulder Score (Quick-DASH) and RTS were assessed. For objective assessment of residual joint instability, a standardized clinical examination as well as a dynamic ultrasound evaluation of the affected and the contralateral elbow was performed. RESULTS: Forty-four patients (26 women, 18 men) with an average age of 41.5 ± 15.3 years were available for follow-up survey (65.5 ± 30.4 months; range 26-123). 21 patients were treated conservatively and twenty-three patients received surgical treatment. CT and ST resulted in similar outcome with regard to ROM, ESAS (CT: 99.4 ± 1.5; ST: 99.8 ± 0.3), MEPS (CT: 97.3 ± 6.8 points; ST: 98.7 ± 3.3) and Quick-DASH (CT: 7.8 ± 10.4; ST: 6.3 ± 7.9) (n.s.). There was no difference in elbow stability and laxity measured by ultrasound between the study groups and compared to the healthy elbow (n.s.). Two patients of the CT group (10%) complained about persistent subjective elbow instability. RTS was faster after surgical compared to conservative treatment (p = 0.036). CONCLUSION: Both, conservative and surgical treatment results in high patient satisfaction and good-to-excellent functional outcome after simple elbow dislocation. Even though ultrasound evaluation showed no significant differences in joint gapping between groups, 10% of conservatively treated patients complained about severe subjective instability. Surgically treated patients returned faster to their preoperatively performed sports. Thus, primary surgical treatment may be beneficial for high demanding patients. LEVEL OF EVIDENCE: Therapeutic study, Level III.

Midterm outcome and strength assessment after quadriceps tendon refixation with suture anchors.

PURPOSE: Quadriceps tendon ruptures (QTR) occur predominantly in middle-aged patients through violent eccentric contraction that occurs either when trying to regain balance or during a fall on the hyperflexed knee. The aim of this study was to quantify midterm postoperative results, including strength potential measured via standardized strength tests following acute (< six weeks) quadriceps tendon refixation using suture anchors. METHODS: All consecutive patients with QTR who underwent surgical suture anchor refixation between 2012 and 2019 at a single institution with a minimum follow-up of 12 months were retrospectively evaluated. Outcome measures included Tegner Activity Scale (TAS), Lysholm score, International Knee Documentation Committee subjective knee form (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS) subscales, return to work rates, and Visual Analog Scale (VAS) for pain. Additionally, a standardized clinical examination and an isometric strength assessment of knee extension and flexion were performed. RESULTS: A total of 17 patients (median age 61.0 [25-75% IQR 50.5-72.5]) were available for final assessment at a mean follow-up of 47.1 ± SD 25.4 months. The majority of patients were male (82.4%) and most injuries occurred due to a fall on the hyperflexed knee (76.5%). The average time interval between trauma and surgery was 12.7 ± 7.5 days. Patients achieved a moderate level of activity postoperatively with a median TAS of 4 (3-5.5) and reported good to excellent outcome scores (Lysholm score: 97 (86.5-100); IKDC: 80.7 ± 13.5; KOOS subscales: pain 97.2 (93.1-100), symptoms 92.9 (82.5-100), activities of daily living 97.1 (93.4-100), sport and recreation function 80 (40-97.5) and knee-related quality of life 87.5 (62.5-100). All patients were able to fully return to work and reported little pain [VAS: 0 (0-0)]. No postoperative complications were reported. Strength measurements revealed a significant deficit of knee extension strength in comparison to the contralateral side (p = 0.011). CONCLUSION: Suture anchor refixation of acute QTR leads to good functional results and high patient satisfaction without major complications. Isometric knee extension strength, however, may not be fully restored compared to the unaffected side.

All-suture anchors for distal biceps tendon repair: a preliminary outcome study.

INTRODUCTION: The aim of this study was to retrospectively evaluate the clinical outcome of double intramedullary all-suture anchors' fixation for distal biceps tendon ruptures. MATERIALS AND METHODS: A retrospective case series of patients who underwent primary distal biceps tendon repair with all-suture anchors was conducted. Functional outcome was assessed at a minimum follow-up of at 12 months based on the assessments of the Mayo Elbow Performance Score (MEPS), Andrews-Carson Score (ACS), Quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH), and the Visual Analog Scale (VAS) for pain. Maximum isometric strength test for flexion and supination as well as postoperative range of motion (ROM) were determined for both arms. RESULTS: 23 patients treated with all-suture anchors were assessed at follow-up survey (mean age 56.5 ± 11.4 years, 96% male). The follow-up time was 20 months (range Q0.25-Q0.75, 15-23 months). The following outcome results were obtained: MEPS 100 (range Q0.25-Q0.75, 100-100); ACS 200 (range Q0.25-Q0.75, 195-200); QuickDASH 31 (range Q0.25-Q0.75, 30-31); VAS 0 (range Q0.25-Q0.75, 0-0). The mean strength compared to the uninjured side was 95.6% (range Q0.25-Q0.75, 80.9-104%) for flexion and 91.8 ± 11.6% for supination. There was no significant difference in ROM or strength compared to the uninjured side and no complications were observed in any patient. CONCLUSION: Distal biceps tendon refixation using all-suture anchors provides good-to-excellent results in terms of patient-reported and functional outcome. This repair technique appears to be a viable surgical option, although further long-term results are needed. LEVEL OF EVIDENCE: Level IV (case series).

Patient education on subacromial impingement syndrome : Reliability and educational quality of content available on Google and YouTube.

OBJECTIVE: The purpose of this study was to assess the reliability and educational quality of content available on Google and YouTube regarding subacromial impingement syndrome (SAIS). METHODS: Google and YouTube were queried for English and German results on SAIS using the search terms "shoulder impingement" and the German equivalent "Schulter Impingement". The analysis was restricted to the first 30 results of each query performed. Number of views and likes as well as upload source and length of content were recorded. Each result was evaluated by two independent reviewers using the Journal of the American Medical Association (JAMA) benchmark criteria (score range, 0-5) to assess reliability and the DISCERN score (score range, 16-80) and a SAIS-specific score (SAISS, score range, 0-100) to evaluate educational content. RESULTS: The 58 websites found on Google and 48 videos found on YouTube were included in the analysis. The average number of views per video was 220,180 ± 415,966. The average text length was 1375 ± 997 words and the average video duration 456 ± 318 s. The upload sources were mostly non-physician based (74.1% of Google results and 79.2% of YouTube videos). Overall, there were poor results in reliability and educational quality, with sources from doctors having a significantly higher mean reliability measured in the JAMA score (p < 0.001) and educational quality in DISCERN (p < 0.001) and SAISS (p = 0.021). There was no significant difference between German and English results but texts performed significantly better than videos in terms of reliability (p = 0.002) and educational quality (p < 0.001). CONCLUSION: Information on SAIS found on Google and YouTube is of low reliability and quality. Therefore, orthopedic health practitioners and healthcare providers should inform patients that this source of information may be unreliable and make efforts to provide patients with higher quality alternatives. LEVEL OF EVIDENCE: IV, case series.

Distal biceps tendon ruptures occur with the almost extended elbow and supinated forearm - an online video analytic study.

BACKGROUND: Distal biceps tendon ruptures can lead to significant restrictions in affected patients. The mechanisms of injury described in scientific literature are based exclusively on case reports and theoretical models. This study aimed to determine the position of the upper extremities and forces involved in tendon rupture through analyzing video recordings. METHODS: The public YouTube.com database was queried for videos capturing a clear view of a distal biceps tendon rupture. Two orthopedic surgeons independently assessed the videos for the activity that led to the rupture, the arm position at the time of injury and the forces imposed on the elbow joint. RESULTS: Fifty-six video segments of a distal biceps rupture were included (55 male). In 96.4%, the distal biceps tendon ruptured with the forearm supinated and the elbow isometrically extended (non-dynamic muscle engagement) (71.4%) or slightly flexed (24%). The most common shoulder positions were adduction (85.7%) and neutral position with respect to rotation (92.9%). Most frequently a tensile force was enacted on the elbow (92.9%) and the most common activity observed was deadlifting (71.4%). CONCLUSION: Distal biceps tendon ruptures were most commonly observed in weightlifting with a slightly flexed or isometrically extended elbow and forearm supination. These observations may provide useful information for sports specific evidence-based injury prevention, particularly in high performing athletes and individuals engaged in resistance training. LEVEL OF EVIDENCE: Observational study.

The risk of suprascapular and axillary nerve injury in reverse total shoulder arthroplasty: An anatomic study.

PURPOSE: Implantation of a reverse total shoulder arthroplasty (rTSA) places the axillary and suprascapular nerves at risk. The aim of this anatomic study was to digitally analyse the location of these nerves in relation to bony landmarks in order to predict their path and thereby help to reduce the risk of neurological complications during the procedure. METHODS: A total of 22 human cadaveric shoulder specimens were used in this study. The axillary and suprascapular nerves were dissected, and radiopaque threads were sutured onto the nerves without mobilizing the nerves from their native paths. Then, 3D X-ray scans of the specimens were performed, and the distance of the nerves to bony landmarks at the humerus and the glenoid were measured. RESULTS: The distance of the inferior glenoid rim to the axillary nerve averaged 13.6mm (5.8-27.0mm, ±5.1mm). In the anteroposterior direction, the distance between the axillary nerve and the humeral metaphysis averaged 8.1mm (0.6-21.3mm, ±6.5mm). The distance of the glenoid centre to the suprascapular nerve passing point under the transverse scapular ligament measured 28.4mm (18.9-35.1mm, ±3.8mm) in the mediolateral direction and 10.8mm (-4.8 to 25.3mm, ±6.1mm) in the anteroposterior direction. The distance to the spinoglenoid notch was 16.6mm (11.1-24.9mm, ±3.4mm) in the mediolateral direction and -11.8mm posterior (-19.3 to -4.7mm, ±4.7mm) in the anteroposterior direction. CONCLUSIONS: Implantation of rTSA components endangers the axillary nerve because of its proximity to the humeral metaphysis and the inferior glenoid rim. Posterior and superior drilling and extraosseous screw placement during glenoid baseplate implantation in rTSA place the suprascapular nerve at risk, with safe zones to the nerve passing the spinoglenoid notch of 11mm and to the suprascapular notch of 19mm.

Annular ligament reconstruction with the superficial head of the brachialis: surgical technique and biomechanical evaluation.

PURPOSE: The purpose of this study was to perform biomechanical testing of annular ligament (AL) reconstruction using the superficial head of the brachialis tendon (SHBT) as a distally based tendon graft. We hypothesized that posterior translation of the radial head following AL reconstruction with an SHBT graft does not significantly differ from intact specimens. METHODS: Six fresh-frozen elbow specimens were used. The stability of the radial head against posterior translation forces (30 N) was evaluated in 0°, 45°, 90° and 120° of elbow flexion. Posterior translation was obtained for the intact AL, the sectioned AL and the reconstructed AL. Cyclic loading (100 cycles) in 90° of elbow flexion was performed for the intact and the reconstructed AL. RESULTS: Posterior translation of the radial head decreased during elbow flexion in native specimens. Sectioning of the AL significantly increased instability over the full range of motion. AL reconstruction with the SHBT restored the stability of the proximal radius but-other than the native AL-was not influenced by elbow flexion. In 120° of flexion the native AL provided significantly more stability when compared to the reconstructed AL. Cyclic loading did not provide significant differences between native and reconstructed specimens. CONCLUSIONS: We provide a feasible technique for AL reconstruction using the SHBT. The biomechanical results obtained in this study confirm the efficacy of the procedure. AL reconstruction restores the stability of the proximal radius, yet it cannot fully mimic the complex features of the intact AL.

The circumferential graft technique for treatment of multidirectional elbow instability: a comparative biomechanical evaluation.

BACKGROUND: Ligament reconstruction with a circumferential graft represents an innovative technique for treatment of multidirectional elbow instability. This biomechanical study compared the stability of the intact elbow joint with the circumferential graft technique and the conventional technique. METHODS: Seven fresh frozen cadaveric elbows were evaluated for stability against valgus and varus/posterolateral rotatory forces (3 Nm) over the full range of motion. Primary stability was determined for intact specimens, after sectioning of the collateral ligaments, after applying the circumferential graft technique (box-loop), and after conventional collateral ligament reconstruction. Cyclic loading (1000 cycles) was performed to assess joint stability and stiffness of the native ligaments and the tendon grafts. RESULTS: Primary stability of both reconstruction techniques was equal to the native specimens (P = .17-.91). Sectioning of the collateral ligaments significantly increased joint instability (P < .001). The reconstruction techniques provided equal stability after 1000 cycles (P = .78). Both were inferior to the intact specimens (P = .02). Cyclic loading caused a significantly lower increase in stiffness of the native ligaments compared with the tendon grafts of either reconstruction technique (P = .001-.008). Significantly better graft stiffness was retained with the circumferential graft technique compared with conventional reconstruction (P = .04). CONCLUSION: Neither reconstruction technique fully reproduces the biomechanical profile of the native collateral ligaments. The circumferential graft technique seems to resist cyclic loading slightly better than the conventional reconstruction technique, yet both reconstruction techniques provide comparable stability.

Elbow Positioning and Joint Insufflation Substantially Influence Median and Radial Nerve Locations.

BACKGROUND: The median and radial nerves are at risk of iatrogenic injury when performing arthroscopic arthrolysis with anterior capsulectomy. Although prior anatomic studies have identified the position of these nerves, little is known about how elbow positioning and joint insufflation might influence nerve locations. QUESTIONS/PURPOSES: In a cadaver model, we sought to determine whether (1) the locations of the median and radial nerves change with variation of elbow positioning; and whether (2) flexion and joint insufflation increase the distance of the median and radial nerves to osseous landmarks after correcting for differences in size of the cadaveric specimens. METHODS: The median and radial nerves were marked with a radiopaque thread in 11 fresh-frozen elbow specimens. Three-dimensional radiographic scans were performed in extension, in 90° flexion, and after joint insufflations in neutral rotation, pronation, and supination. Trochlear and capitellar widths were analyzed. The distances of the median nerve to the medial and anterior edge of the trochlea and to the coronoid were measured. The distances of the radial nerve to the lateral and anterior edge of the capitulum and to the anterior edge of the radial head were measured. We analyzed the mediolateral nerve locations as a percentage function of the trochlear and capitellar widths to control for differences regarding the size of the specimens. RESULTS: The mean distance of the radial nerve to the lateral edge of the capitulum as a percentage function of the capitellar width increased from 68% ± 17% in extension to 91% ± 23% in flexion (mean difference = 23%; 95% confidence interval [CI], 5%-41%; p = 0.01). With the numbers available, no such difference was observed regarding the location of the median nerve in relation to the medial border of the trochlea (mean difference = 5%; 95% CI, -13% to 22%; p = 0.309). Flexion and joint insufflation increased the distance of the nerves to osseous landmarks. The mean distance of the median nerve to the coronoid tip was 5.4 ± 1.3 mm in extension, 9.1 ± 2.3 mm in flexion (mean difference = 3.7 mm; 95% CI, 2.04-5.36 mm; p < 0.001), and 12.6 ± 3.6 mm in flexion and insufflation (mean difference = 3.5 mm; 95% CI, 0.81-6.19 mm; p = 0.008). The mean distance of the radial nerve to the anterior edge of the radial head increased from 4.7 ± 1.8 mm in extension to 7.7 ± 2.7 mm in flexion (mean difference = 3.0 mm; 95% CI, 0.96-5.04 mm; p = 0.005) and to 11.9 ± 3.0 mm in flexion with additional joint insufflation (mean difference = 4.2 mm; 95% CI, 1.66-6.74 mm; p = 0.002). CONCLUSIONS: The radial nerve shifts medially during flexion from the lateral to the medial border of the inner third of the capitulum. The median nerve is located at the medial quarter of the joint. The distance of the median and radial nerves to osseous landmarks doubles from extension to 90° flexion and triples after joint insufflation. CLINICAL RELEVANCE: Elbow arthroscopy with anterior capsulectomy should be performed cautiously at the medial aspect of the joint to avoid median nerve lesions. Performing arthroscopic anterior capsulectomy in flexion at the lateral aspect of the joint and in slight extension at the medial edge of the capitulum could enhance safety of this procedure.

The course of the median and radial nerve across the elbow: an anatomic study.

INTRODUCTION: Nerve transection has been described as complication of arthroscopic elbow arthrolysis. Therefore, the goal of this study was to define bony landmarks for intraoperative orientation regarding the location of the median and radial nerve. METHODS: In 22 formalin-fixated upper extremities, the radial and median nerves were dissected and marked with respect to their native course. A 3D X-ray scan was performed. The distances of the radial nerve to the radial head (R1), the capitulum (R2), and its lateral border (RC) were measured. The location of the radial nerve in relation to the transversal diameter of the humeral condyle (HC) was calculated. Similarly, the distances of the median nerve to the trochlea (M1), the medial border of the trochlea (M2), and its relation to HC were calculated. RESULTS: The mean value for R1 was 8 mm (±2.9 mm), for R2 was 11.3 mm (±3.8 mm), and for RC was 10.6 mm (±5.1 mm). RC/HC averaged 24 % (±11 %). M1 averaged 11.7 mm (±5.2 mm), and M2 was 2.4 mm (±4.1 mm). M2/HC averaged 6 % (±9 %). CONCLUSIONS: The radial nerve is located ventral to the central third of the capitulum. The median nerve lies ventral to the medial quarter of the humeral condyle. When performing arthroscopic arthrolysis, this information should be kept in mind during anterior capsulectomy.

Course of the radial nerve in relation to the center of rotation of the elbow--the need for a rational safe zone for lateral pin placement.

PURPOSE: To investigate the course and variability of the radial nerve along the lateral humerus in relation to the center of rotation of the elbow joint in the context of lateral pin placement for hinged external fixation. METHODS: A total of 95 formalin-fixed upper extremities were dissected. The course of the radial nerve along the lateral aspect of the humerus was measured at 3 landmarks with respect to the center of rotation of the elbow. We analyzed the data and the landmark positions correlated with the length of the humerus. RESULTS: The measured positions of 3 landmarks of the radial nerve in the lateral aspect of the humerus ranged from 19% to 43% of the length of the humerus and were located, on average, 6.0, 9.7, and 13.5 cm from the lateral center of rotation. CONCLUSIONS: These data help predict the humeral course of the radial nerve and define a safe zone for pin implantation. However, because of variability in the course of the radial nerve, a safe zone cannot fully ensure prevention of iatrogenic injury to the nerve. The safest method of pin application remains mini-open dissection and visual implantation. CLINICAL RELEVANCE: Based on this cadaveric study, it is not possible to define a rational safe zone. The safest method of pin application for dynamic external fixation of the elbow is to perform a mini-open dissection with direct visualization.