Cadaveric Elbow Specimens Research Articles

Evaluating the efficacy of hinged elbow braces in reducing passive valgus forces after ulnar collateral ligament injury-A biomechanical study.

This biomechanical study aimed to investigate the effectiveness of a hinged elbow orthosis in reducing passive valgus forces following medial ulnar collateral ligament (UCL) injuries of the elbow joint. The hypothesis tested was that a hinged elbow orthosis reduces these passive valgus forces. Eight fresh frozen cadaveric elbow specimens were prepared and tested under three scenarios: intact ligaments, simulated UCL rupture and application of a hinged elbow brace after simulated UCL rupture. Valgus instability was assessed using a custom testing set-up and the Optotrak motion capture system. Statistical analysis was conducted to compare the results across scenarios. Intraclass correlation (ICC) calculation showed that the testing set-up was reliable in investigating valgus deflection across all levels of applied force. The hinged elbow brace reduced passive valgus forces after UCL rupture. The reduction in valgus instability was consistent with close approximation to the native state, although not reaching its level. The hypothesis-that a hinged elbow orthosis significantly reduces passive valgus forces in the elbow following UCL injuries-is not supported by the data and therefore has to be rejected. Nevertheless, the study demonstrates a tendency that a hinged elbow brace could mitigate these forces, at least in an experimental cadaveric model with static study conditions. The level of evidence of this study is level IV.

Static Stability of Elbow Interposition Arthroplasty Stabilized With Novel Ligament Reconstruction.

Outcomes of interposition arthroplasty for treatment of elbow arthritis are highly dependent on elbow stability. The purpose of this study was to determine whether interposition arthroplasty with a novel bidirectional ligament reconstruction technique could adequately restore the static stability of the native elbow. Static varus and valgus elbow stability was tested in 7 cadaver elbows with intact ligaments and capsule at 5 flexion angles (0°, 30°, 60°, 90°, and 120°). At each angle, the distance between fixed reference points across the elbow was measured both medially and laterally. The elbows were then destabilized and an interposition arthroplasty with ligament reconstruction was performed. Static elbow stability was reassessed by comparing postoperative deflection measurements with those of the native state. Graft slippage or loosening was visually assessed following testing. Interposition arthroplasty was performed in 7 cadaver specimens. Following ligament reconstruction, specimens reproduced the flexion angle-dependent static stability of native elbows to both varus and valgus stress. The greatest deflection changes between native elbows and elbows after interposition arthroplasty were 2.7% (P = .13) medially and 2.3% (P = .42) laterally, which were not significant. There was no loosening or slippage of either the interposition graft or the ligament reconstruction grafts. Cadaveric elbow specimens underwent interposition arthroplasty with a novel technique for bidirectional ligament reconstruction. Static stability was maintained at varying degrees of elbow flexion, comparable to that of the native elbow. Interposition and ligament reconstruction grafts maintained secure fixation following static biomechanical testing.

Augmented Ulnar Collateral Ligament Repair With Structural Bioinductive Scaffold: A Biomechanical Study

Background: Elbow ulnar collateral ligament (UCL) repair with suture brace augmentation shows good time-zero biomechanical strength and a more rapid return to play compared with UCL reconstruction. However, there are concerns about overconstraint or stress shielding with nonabsorbable suture tape. Recently, a collagen-based bioinductive absorbable structural scaffold has been approved by the Food and Drug Administration for augmentation of soft tissue repair. Purpose/Hypothesis: This study aimed to assess the initial biomechanical performance of UCL repair augmented with this scaffold. We hypothesized that adding the bioinductive absorbable structural scaffold to primary UCL repair would impart additional time-zero restraint to the valgus opening. Study Design: Controlled laboratory study. Methods: Eight cadaveric elbow specimens—from midforearm to midhumerus—were utilized. In the native state, elbows underwent valgus stress testing at 30o, 60o, and 90o of flexion, with a cyclical valgus rotational torque. Changes in valgus rotation from 2- to 5-N·m torque were recorded as valgus gapping. Testing was then performed in 4 states: (1) native intact UCL—with dissection through skin, fascia, and muscle down to an intact UCL complex; (2) UCL-transected—distal transection of the ligament off the sublime tubercle; (3) augmented repair with bioinductive absorbable scaffold; and (4) repair alone without scaffold. The order of testing of repair states was alternated to account for possible plastic deformation during testing. Results: The UCL-transected state showed the greatest increase in valgus gapping of all states at all flexion angles. Repair alone showed similar valgus gapping to that of the UCL-transected state at 30° (P = .62) and 60° of flexion (P = .11). Bioinductive absorbable scaffold–augmented repair showed less valgus gapping compared with repair alone at all flexion angles (P = .021, P = .024, and P = .024 at 30°, 60°, and 90°, respectively). Scaffold-augmented repair showed greater gapping compared with the native state at 30° (P = .021) and 90° (P = .039) but not at 60° of flexion (P = .059). There was no difference when testing augmented repair or repair alone first. Conclusion: UCL repair augmented with a bioinductive, biocomposite absorbable structural scaffold imparts additional biomechanical strength to UCL repair alone, without overconstraint beyond the native state. Further comparative studies are warranted. Clinical Relevance: As augmented primary UCL repair becomes more commonly performed, use of an absorbable bioinductive scaffold may allow for improved time-zero mechanical strength, and thus more rapid rehabilitation, while avoiding long-term overconstraint or stress shielding.

Static stability of novel uncemented elbow hemiarthroplasty stabilized with ligament reconstruction

The purpose of this study was to create a model to simulate treatment of unreconstructable distal humerus fractures with hemiarthroplasty. Stability was restored with a new plate-system that simultaneously tensions medial and lateral collateral ligament grafts. Static varus and valgus elbow stability was tested in 11 cadaver elbows with intact ligaments and capsule at five flexion angles (0, 30, 60, 90, 120 degrees). The elbows were then destabilized via release of all ligaments and capsular attachments. The distal humerus articular cartilage was excised and replaced with an uncemented hemiarthroplasty. Ligament reconstruction was subsequently performed, and elbow stability was measured and compared to the native state. Dimensions of the hemiarthroplasty component were compared to native elbow dimensions to assess and quantify any existing relationship to elbow stability. A hemiarthroplasty was implanted in all specimens. A size mismatch occurred between the distal humerus trochlea and the olecranon fossa in all specimens and averaged 6.3 mm. Following ligament reconstruction, specimens reproduced the flexion angle-dependent stability of native elbows to both varus and valgus stress. On the medial side, elbow joint stability in mid-flexion was approximately 7% tighter after hemiarthroplasty. Laterally, the elbow was approximately 15% tighter after hemiarthroplasty and demonstrated peak stability in full flexion. The three assessed hemiarthroplasty components and bony dimensions did not exhibit any relationship between implant-bone mismatch and elbow stability after ligamentous reconstruction. Cadaveric elbow specimens underwent uncemented hemiarthroplasty with soft tissue stabilization with a novel technique for ligament reconstruction. Following hemiarthroplasty and ligament reconstruction, these specimens maintained secure fixation between ligament and bone. Static stability was maintained at varying degrees of elbow flexion regardless of variable mismatch between the hemiarthroplasty component and the native olecranon fossa.

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

ObjectivePartial 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.MethodsEighteen 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.ResultsA 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.DiscussionPartial 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.

The simulation of terrible triad injuries in fresh-frozen human cadaveric specimens with intact soft tissue envelope

IntroductionThe aim of the present study was to develop a technical process to reproducibly generate terrible triad injuries (TTI) in fresh-frozen human cadaveric specimens, while leaving the skin intact. Such “pre-fractured” specimens, used for scientific analysis and for surgical education, might help to improve current treatment, which is complex and prone to complications.Materials and methodsTo induce the desired fractures, a custom-made fracturing unit was used to apply an axial force on the extended cadaveric elbow specimens, with the forearm pronated and under valgus load. To simulate the valgus load, a pneumatic cylinder was developed to apply valgus stress to the joint by an additional force vector from the lateral side of the joint.ResultsThe success rate of TTI induction was 92.3% (12/13). Of the 12 radial head fractures, 3 (25%) were classified Mason type II and 9 (75%) Mason type III. The coronoid fractures were grouped in tip subtype 2 (5 fractures, 41.7%), anteromedial facet (AMF) subtype 2 (4 fractures, 33.3%), AMF subtype 3 (1 fracture, 8.3%) and basal subtype 1 (2 fractures, 16.7%).ConclusionsThe present study provides an instrument for successful and reproducible production of dislocation fracture patterns with their typical accompanying soft tissue lesions. The methodology might be applied on a broad basis to be able to perform biomechanical studies regarding primary stability of fixation concepts for TTI and to educate surgeons in a fairly realistic scenario with the surgical treatment of TTI.

Valgus fatigue and nonlinear damage accretion of the anterior bundle of the elbow medial collateral ligament (AMCL)

Failure by fatigue is one mechanism by which ligaments can rupture, with the accumulation of damage gradually degrading the ligament strength. Baseball pitchers who perform repeated high-level throwing continuously subject the medial ligament complex of the elbow to extreme levels of loading, which can lead to fatigue and eventual rupture. This study sought to investigate this behavior and quantify the fatigue properties of the anterior bundle of the medial collateral ligament (AMCL) with respect to valgus elbow torque. Eleven pairs of cadaveric elbow specimens were used for this study. One side of each pair was tested in vertical elongation at four flexion angles and then tested to failure at 90° of flexion. The contralateral specimens were tested in valgus fatigue at 90° of flexion using a specialized apparatus with application of known moments based on the elongation failure load. The average tensile failure load for the AMCL was 595.3 ± 201.9 N. During cycling, the average increase in the maximum valgus rotation angle was 4.77° ± 2.82°. The average maximum stretch of the AMCL middle band increased from 1.066 ± 0.017 to 1.076 ± 0.018 near the time of fatigue failure. The average cycles to failure for specimens tested at 90% and 80% of the estimated failure torque were 3211 ± 4721.33 and 25063 ± 30487.58, respectively. The nonlinear non-dimensional fatigue life and damage accretion results work in conjunction to predict the fatigue properties for a valgus elbow motion of arbitrary torque magnitude at 90° of elbow flexion.

Use of Digital Tomosynthesis in Assessing Accurate Medial Epicondyle Fracture Displacement as Compared With Conventional Radiography and Computed Tomography.

Introduction:Medial epicondyle fracture displacement is notoriously difficult to determine on conventional radiography, and follow-up computed tomography (CT) is often obtained to measure precise displacement. Another option for fracture characterization is digital tomosynthesis (DT), a technology providing high in-plane resolution of bony anatomy by acquiring multiple low-dose images in a linear arc. Advantages of DT include lower radiation exposure and lower cost than CT, rapid image acquisition, and a similar patient experience to conventional radiography. The digital application of tomosynthesis is relatively new and is integrated as an add-on feature with modern radiography equipment. This study compares DT, CT and conventional radiography for measurement accuracy in medial epicondyle fractures with the goal of determining relative accuracy in measuring medial epicondyle fracture displacement.Methods:Medial epicondyle fractures were created in 5 cadaveric elbow specimens. Each specimen was imaged with conventional radiography, DT, and CT. True displacement measured by digital calipers was compared with “measured” displacement for each image acquisition. CT images included axial, sagittal, and coronal reformats. DT images of the elbow included anteroposterior (AP) longitudinal and transverse, lateral longitudinal and transverse, and axial longitudinal and transverse. Conventional radiographs included AP, lateral, and axial distal humerus images. Four physicians reviewed all images 3 months later. Each reviewer independently measured maximum apparent fracture displacement to the nearest 0.1 mm. Measurement accuracy was calculated as percent difference [(measured displacement−actual displacement)/actual displacement] for each acquisition. Mean, median, and SD for measurement accuracy were calculated. Two-tailed paired t tests were performed on each acquisition to compare the measurement accuracy.Results:Compared with conventional radiographs, accuracy of DT was superior in AP longitudinal (P=0.03), AP transverse (P=0.01), axial longitudinal (P=0.0001), and axial transverse projections (P=0.001). Accuracy of CT was superior to conventional radiography in the AP projection (P=0.03), but was equivalent in the axial projection (P=0.9). Accuracy of CT was similar to DT in AP longitudinal (P=0.6), AP transverse (P=0.5), and axial longitudinal projections (P=0.07). Accuracy of DT in the axial transverse projection was superior to CT (P=0.03).Conclusion:DT is more accurate than conventional radiography (both AP and axial views) and as accurate as CT in assessing millimeters of displacement of medial epicondyle fracture fragments.Level of Evidence:Level IV—diagnostic study.

Histologic Evaluation of the Triceps Brachii Tendon Insertion: Implications for Triceps-Sparing Surgery

Triceps detachment and olecranon osteotomy are 2 techniques used to enhance exposure in elbow surgery. Both the techniques can potentially add considerable morbidity and lengthen the recovery after surgery. Triceps-sparing surgery can potentially mitigate those issues. The purpose of this study was to evaluate the triceps tendon insertion at a histologic level to help improve triceps-sparing surgical techniques used in elbow trauma and arthroplasty. Seventeen fresh-frozen cadaveric elbow specimens were collected. The olecranon and its soft tissue attachments were isolated. We performed gross measurements and sectioned the specimens for histologic evaluation in the saggital or coronal planes. The proximal-to-distal and medial-to-lateral dimensions of the tendon and the distance from the proximal tip of the olecranon to the proximal tendon insertion were measured microscopically on stained embedded sections. The proximal-to-distal dimension of the triceps tendon insertion was less than previously reported, whereas the medial-to-lateral dimension was similar. The true distance from the tip of the olecranon to the proximal tendon insertion was greater than the previously reported distance obtained via gross measurement. Gross measurement of the triceps tendon insertion overestimates and inaccurately represents the true insertional footprint. Gross measurement has been shown to demonstrate consistent disparity compared with histologic measurement. Histologic investigation provides a more accurate description. The finding that the distance from the articular tip of the olecranon to the proximal tendon insertion is greater than previously reported may have clinical implications. A triceps split approach may allow more visualization and exposure of the posterior joint and, therefore, lessen the need for triceps detachment or olecranon osteotomy.

Histologic Analysis of 2 Alternative Donor Sites of the Ipsilateral Elbow in the Treatment of Capitellar Osteochondritis Dissecans

To compare the histologic features of the cartilage from the capitellum with 2 proposed alternative donor sites from the ipsilateral elbow in the treatment of capitellar osteochondritis dissecans (OCD): the nonarticulating part of the radial head and the nonarticulating lateral side of the olecranon tip. Ten human cadaveric elbow specimens with macroscopically normal articular surfaces were used to obtain 5-mm osteochondral grafts: 10 from the capitellum (60° anteriorly relative to the humeral shaft), 10 from the radial head (nonarticulating part at 80°), and 4 from the olecranon (lateral side of the olecranon tip). Grafts were fixated in formalin (4% formaldehyde), decalcified, and processed into standard 8-μm-thick hematoxylin and eosin-and Toluidine Blue-stained sections. These were assessed for cartilage thickness, shape of articular surface, and 13 histologic parameters of the International Cartilage Repair Society II. Olecranon scores were excluded from statistical analysis. Mean cartilage thickness was 1.5 ± 0.22mm at the capitellum; 1.3 ± 0.34mm at the radial head; and 1.9 ± 1.0mm at the olecranon. There was no difference in cartilage thickness between the capitellum and radial head (P= .062). All grafts demonstrated a convex articular surface. International Cartilage Repair Society II scores ranged from 82 to 100 for the capitellum, from 81 to 100 for the radial head, and from 67 to 87 for the olecranon tip. There was less chondrocyte clustering at the capitellum (84 ± 14) than in the radial head (94 ± 3.2; P= .019). Mid/deep zone assessment of the capitellum scored higher (97 ± 6.7) than the radial head (91 ± 4.6; P= .038). This study demonstrates appropriate histologic similarities between the cartilage from the capitellum and 2 alternative donor sites of the ipsilateral elbow in the treatment of capitellar OCD: the nonarticulating part of the radial head and the nonarticulating lateral side of the olecranon tip. From an histologic point of view, there seem to be no obstacles to use grafts from these alternative donor sites for reconstruction of the capitellum when performing osteochondral autologous transplantation.

Correlation of Force to Deformation of the Anterior Bundle of the Medial Collateral Ligament Through Consideration of Band Laxity.

The anterior bundle of the medial collateral ligament (AMCL) resists the loads that arise at the elbow during overhand throwing and has commonly been divided into posterior and anterior bands. While these anterior and posterior bands have been thought to bear the load at different flexion angles, any transition of the load distribution between the two bands is poorly understood and has not considered laxity (slack). This study considers the AMCL as three bands and quantifies the mechanical response to vertical distraction, simulating valgus-load joint opening, through the sequential superposition of the band responses after the elimination of inherent laxity. Eight cadaveric elbow specimens were used for the study. The intact AMCL of each specimen was tested under vertical distraction in a specialized load frame at four elbow flexion angles and then subsequently retested after two longitudinal transections. The greatest laxity at full extension and full flexion belonged to the posterior (1.9 mm) and anterior (2.4 mm) band, respectively. At the lesser and higher flexion angles, the greatest structural stiffness belonged to the anterior and middle band. The overall AMCL was the most structurally stiff at 60°, with approximately 150 N of force required for 2% elongation. This study shows that the different bands of the AMCL may have different load bearing properties at different flexion angles, causing each band to support different proportions of an imposed load. The presence of the laxity may impose a load-bearing delay, causing load-bearing in each band to begin asynchronously. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2027-2034, 2019.

Articulated Joint Distraction in a Cadaveric Model of the Canine Elbow.

The aim of this study was to determine if articulated joint distraction in the canine elbow can effectively maintain a distraction gap between the articular surfaces of the canine elbow under a weight-bearing load. An articulated external skeletal fixator with turnbuckles was applied to seven canine cadaveric elbow specimens. Specimens were potted and mechanically tested at 135° of flexion, while joint contact pressure was recorded at three locations within the elbow. Joint distraction was sequentially increased, and loads of 5 N, 90 N and 180 N were incrementally applied. This process was repeated until no pressure was recorded at each of the three locations within the elbow under 180 N of applied load. To achieve 0 N of joint contact force with 180 N of axial load, the average amount of distraction needed was 2.3 ± 0.71 mm (range, 1.8-3.6 mm) at the distal turnbuckles and 1.67 ± 1.10 mm (range, 1.8-2.7 mm) at the proximal turnbuckles. Results suggest that joint distraction can effectively decrease articular pressure within the canine elbow joint. A maximum of 3.6 mm of distraction between the fixator turnbuckles was necessary to eliminate joint contact for the construct tested. Clinical investigation is necessary to establish if articulated elbow joint distraction is a safe and effective for the treatment of canine elbow osteoarthritis.

Étude du capitellum après prothèse de tête radiale : une étude biomécanique contrôlée sur un modèle cadavérique de fracture de la tête radiale

BackgroundWe asked whether either open reduction and internal fixation (ORIF) or radial head arthroplasty (RHA), common techniques used for the confrontation of displaced or comminuted radial head fractures, are correlated with cartilage wear of the capitulum. HypothesisWe hypothesized that neither ORIF nor RHA are correlated with capitellar cartilage wear. Material and methodsOn 5 cadaveric elbow specimens, osteotomies were employed to simulate radial head comminuted fractures followed with ORIF by Herbert screws. Radial heads were also excised from other 5 cadaveric elbow specimens and were replaced by metallic monopolar implants. Finally, 2 elbows were not operated and used as a control group. Custom-made rotary machines, working unstoppably, generated 700,000 pronation and supination forearm movements at an 110° arc of motion. The elbow joints were examined with pre- and postoperative Magnetic Resonance Imaging (MRI) scans and the articular surfaces of the capitula were resected and sent for histopathology study. ResultsIn the 2 cadaveric elbows of the control group and the 4 elbows treated with ORIF no cartilage damage was found. The fifth one displayed cartilage fissures, which were classified according to International Cartilage Repair Society (ICRS) grading system as grade I cartilage damage. On the contrary, all 5 elbows treated with RHA sustained complete cartilage loss, exposure of the subchondral bone and were classified as ICRS grade IV cartilage damage. DiscussionOur study suggests that metallic monopolar RHA after a displaced or comminuted radial head fracture carries a high risk of rapidly evolving cartilage loss of the capitulum.Basic Science, Biomechanical Cadaveric Study.

Capitellar erosion after radial head arthroplasty: A comparative biomechanical study of operated radial head fractures on cadaveric specimens

We asked whether open reduction and internal fixation (ORIF) or radial head arthroplasty (RHA), common techniques used for the confrontation of displaced or comminuted radial head fractures, are correlated with cartilage wear of the capitulum. We hypothesized that neither ORIF nor RHA are correlated with capitellar cartilage wear. On 5 cadaveric elbow specimens, osteotomies were employed to simulate radial head comminuted fractures followed with ORIF by Herbert screws. Radial heads were also excised from other 5 cadaveric elbow specimens and were replaced by metallic monopolar implants. Finally, 2 elbows were not operated and used as a control group. Custom-made rotary machines, working unstoppably, generated 700,000 pronation and supination forearm movements at a 110° arc of motion. The elbow joints were examined with pre- and postoperative magnetic resonance imaging (MRI) scans and the articular surfaces of the capitula were resected and sent for histopathology study. In the 2 cadaveric elbows of the control group and the 4 elbows treated with ORIF, no cartilage damage was found. The fifth one displayed cartilage fissures, which were, classified according to International Cartilage Repair Society (ICRS) grading system as grade I cartilage damage. On the contrary, all 5 elbows treated with RHA sustained complete cartilage loss, exposure of the subchondral bone and were classified as ICRS grade IV cartilage damage. Our study suggests that metallic monopolar RHA after a displaced or comminuted radial head fracture carries a high risk of rapidly evolving cartilage loss of the capitulum.

Evaluating the Utility of the Lateral Elbow Radiograph in Central Articular Olecranon Reduction: An Anatomic and Radiographic Study.

The surgical reduction of intra-articular olecranon fractures is judged primarily on the lateral elbow radiograph, as orthogonal imaging of the articular surface is not obtainable. We sought to determine surgeon accuracy in identifying intra-articular olecranon malreductions on the lateral elbow radiograph. Six human fresh-frozen cadaveric elbow specimens were sagittally sectioned in 5-mm increments after olecranon dissection, preservation of soft tissue envelope, and rigid fixation of the elbow in an external fixator. Three patterns of central intra-articular olecranon malreduction were created in each elbow using a ruler and bone saw. Perfect lateral elbow radiographs were taken of each malreduction, and these images were randomized along with x-rays of normal cadaveric olecranons. The image series was presented to 4 masked trauma-trained surgeons to determine whether the olecranon was malreduced or anatomic. Surgeons interpreted the same image series on 2 separate occasions separated by 6 weeks. Percent correct was recorded, and the interobserver and intraobserver reliability was calculated. Orthopedic trauma surgeons correctly identified olecranon malreductions only 73% of the time on the lateral elbow radiograph. Interobserver agreement was moderate for the first review of images and fair for the second review, with respective Fleiss Kappa values of 0.43 and 0.28. Intrarater reliability revealed moderate agreement with Cohen's Kappa value ranging from 0.56 to 0.66. Intra-articular olecranon malreductions are inconsistently recognized by trauma surgeons on the lateral elbow radiograph. Therefore, articular incongruity may still be present after surgical fixation of comminuted olecranon fractures. We must further define the radiographic anatomic representation of the articular olecranon to improve surgical reduction and clinical outcomes.

Modified Anterolateral Portals in Elbow Arthroscopy: A Cadaveric Study on Safety

To evaluate the proximity to the radial nerve on cadaveric specimens of 2 modified anterolateral portals used for elbow arthroscopy. Ten fresh cadaveric elbow specimens were prepared. Four-millimeter Steinman pins were inserted into 3 anterolateral portal sites in relation to the lateral epicondyle: (1) the standard distal anterolateral portal, (2) a modified direct anterolateral portal, and (3) a modified proximal anterolateral portal. These were defined as follows: direct portals 2cm directly anterior to the lateral epicondyle, and proximal portals 2cm proximal and 2cm directly anterior to the lateral epicondyle. Each elbow was then dissected to reveal the course of the radial nerve. Digital photographs were taken of each specimen, and the distance from the Steinman pin to the radial nerve was measured. The modified proximal anterolateral and direct anterolateral portals were found to be a statistically significant distance from the radial nerve compare to the distal portal site (P= .011 and P= .0011, respectively). No significant difference was found in the proximity of the radial nerve between the modified proximal and direct anterolateral portals (P= .25). Inadequate imaging was found at a single portal site for the proximal site; 9 specimens were used for analysis of this portal with 10 complete specimens for the other 2 sites. In cadaveric analysis, both the modified proximal and direct lateral portals provide adequate distance from the radial nerve and may be safe for clinical use. In this study, the distal anterolateral portal was in close proximity of the radial nerve and may result in iatrogenic injury in the clinical setting. This is a cadaveric analysis of 2 modified portal locations at the anterolateral elbow for use in elbow arthroscopy. Further clinical studies are needed prior to determining their absolute safety in comparison to previously identified portal sites.

Biomechanical evaluation of distal biceps tendon repair using tension slide technique and knotless fixation technique

Acute distal biceps tendon ruptures are uncommon injuries that often affect young active males, typically resulting from an eccentric load on their dominant extremity. The purpose of this study was to compare pullout strength and tendon gapping in the tension slide technique (TST) versus a knotless fixation technique (KFT). Two sets of experiments were performed using cadaveric elbow specimens. In the first experiment, eight elbows from different cadavers were tested to compare TST with a standard locking whipstitch with KFT, four elbows in each group, using a standard locking whipstitch. In the second experiment, 12 elbows were used to study the differences between TST with a standard locking whipstitch with KFT using suture tape reinforced whipstitch (RKFT), using the TST data from the first and second experiment. Each experiment evaluated gapping after cyclic loading and the second experiment also tested the construct to load to failure. Gapping for KFT with a standard locking whipstitch was 10.64mm versus 2.69mm for the TST after 1000cycles (P=0.016). A reinforced whipstitch significantly improved the failure to gap on the KFT with no significant difference in gapping when compared to TST after 3000cycles (P=0.36). The resultant gapping for TST and KST was 2.08mm and 2.99mm (P=0.91), respectively. Load to failure for TST and KFT were 282Nm and 328Nm (P=0.20), respectively. Bone-tendon gap resistance of a KFT repair of a torn distal biceps tendon is limited by suture technique. Using a tape reinforced locking whipstitch, the repair is as strong as TST repair. Basic Science.

Concomitant injury of the annular ligament in fractures of the coronoid process and the supinator crest

Fractures of the coronoid process or the supinator crest, as well as arthroscopic resection of osteophytes around the coronoid process, can endanger the attachment of the annular ligament (AL) to the proximal ulna. The purpose of this study was to investigate the corresponding insertional areas of the AL within this context. In 30 embalmed human cadaveric elbow specimens, the insertional area of the AL at the anterior and posterior margin of the sigmoid notch was characterized. The distances and relations of the AL insertion anteriorly to the coronoid surface, the coronoid tip, and the depth of the coronoid process, as well as posteriorly to the supinator crest, were evaluated macroscopically. The mean distance of the anterior insertion area was 1.9 ± 0.6 mm (range, 1.0-3.1 mm) to the coronoid articular surface and 6.2 ± 1.7 mm (range, 2.9-10.2 mm) to the tip of the coronoid. The distance of the anterior insertion in relation to the depth of the coronoid process was 44% ± 11% (range, 30%-69%). The distance of the posterior insertion area to the level of the sigmoid notch measured from 3.5 ± 1.5 mm (range, 0.5-6.5 mm) to 17.7 ± 2.9 mm (range, 13.1-25.4 mm). Coronoid fractures involving 44% or more of the coronoid process and anterolaterally oriented fractures where one-third of the anterolateral facet is affected are accompanied by a complete anterior bony disruption of the AL. Arthroscopic resection of the coronoid tip should be limited to 1 mm distal to the coronoid articular surface to avoid injury to the AL. Fractures of the upper half of the supinator crest place the AL at risk at its posterior insertion.

Two Modified Anterolateral Portals in Elbow Arthroscopy: A Cadaveric Study

To analyze the placement of two modified anterolateral portal sites in elbow arthroscopy and demonstrate the safety of each with respect to portal sites proximity to the radial nerve. Twelve fresh cadaveric elbow specimens (6 matched pairs) were prepared, anatomic landmarks were marked, and 4mm Steinman pins were inserted into three anterolateral portal sites in relation to the lateral epicondyle: 1) proximal, 2cm proximal and 2cm anterior 2) direct anterior, 2cm anterior 3) distal, 3cm distal and 1cm anterior. Each elbow was then dissected to reveal the course of the radial nerve. Digital photographs were taken of each specimen and the distance from the Steinman pin and the radial nerve was measured. Our proximal and direct anterior portal sites were found to be an average of 11.1mm and 13.8mm from the radial nerve, respectively. Similar to past studies we found the original distal anterolateral portal, as described by Andrews and Carson, in close proximity to the radial nerve, an average distance of 4.5mm. The distal anterolateral portal came in contact with the radial nerve 40% of the time, with 3 total Steinman pins piercing the nerve. There was a statistically significant difference in the distance between our proximal and distal anterior portals, as well as, our direct anterior and the distal portals to the radial nerve. No significant difference was found between the distance of the proximal and direct anterior portal sites. Our two modified, proximal and direct anterior, anterolateral portal sites should be considered safe and provides the surgeon with an adequate distance between the arthroscope and the radial nerve with little risk of iatrogenic injury. The distal portal puts the radial nerve at the most risk for iatrogenic injury. Our two modified anterolateral portal sites should be considered for use when performing elbow arthroscopy.

Sonographically guided distal biceps tendon injections: techniques and validation.

The primary purpose of this investigation was to describe and validate sonographically guided techniques for distal biceps peritendinous/intratendinous injections using a cadaveric model. A single experienced operator completed 18 sonographically guided distal biceps peritendinous injections and 15 sonographically guided distal biceps intratendinous injections in 18 unembalmed cadaveric elbow specimens (11 male and 7 female; age, 53-100 years; body mass index, 19.4-42.2 kg/m(2)). Four different peritendinous approaches were used to inject 3 mL of diluted yellow latex: (1) anterior/superficial, (2) posterior/superficial, (3) posterior/deep/short-axis (to the distal biceps tendon), and (4) posterior/deep/long-axis (to the distal biceps tendon). Three different intratendinous approaches were used to inject 1 mL of diluted blue latex: (1) anterior, (2) anterior/pronator window, and (3) posterior. The feasibility of all 7 injections was assessed by the operator in all specimens, and execution difficulty was recorded after each injection. Specimens were subsequently dissected to assess injectate placement. All 18 peritendinous distal biceps tendon injections accurately placed latex around the tendon without injecting into the tendon proper. All posterior/superficial peritendinous injections delivered injectate to the ulnar side of the tendon. All posterior/deep peritendinous injections delivered injectate to the radial side of the tendon, with the long-axis approach being technically easier than the short-axis approach. Anterior/superficial peritendinous injections delivered injectate predominantly to the anterior side of the tendon and resulted in 1 brachial artery injury. All but 1 of 15 distal biceps intratendinous injections (93%) accurately placed injectate into the tendon proper, with 1 of 5 anterior injections delivering injectate primarily deep to the paratenon. The posterior intratendinous approach was technically the easiest. No intratendinous injection resulted in neurovascular injury. Sonographically guided distal biceps peritendinous/intratendinous injections are feasible and therefore may play a role in the management of patients presenting with distal biceps tendinopathy/bursopathy.