Hemolysis contributes to anemia during long-duration space flight.

Anemia in astronauts has been noted since the first space missions, but the mechanisms contributing to anemia in space flight have remained unclear. Here, we show that space flight is associated with persistently increased levels of products of hemoglobin degradation, carbon monoxide in alveolar air and iron in serum, in 14 astronauts throughout their 6-month missions onboard the International Space Station. One year after landing, erythrocytic effects persisted, including increased levels of hemolysis, reticulocytosis and hemoglobin. These findings suggest that the destruction of red blood cells, termed hemolysis, is a primary effect of microgravity in space flight and support the hypothesis that the anemia associated with space flight is a hemolytic condition that should be considered in the screening and monitoring of both astronauts and space tourists.

Quantitative analysis of repaired rabbit supraspinatus tendons (± channeling) using magnetic resonance imaging at 7 Tesla.

BACKGROUND: The quantitative assessment of supraspinatus tendons by conventional magnetic resonance is limited by low contrast-to-noise ratio (CNR). Magnetic resonance imaging (MRI) scanners operating at 7 Tesla offer high signal-to noise ratio (SNR), low CNR and high spatial resolution that are well-suited for rapidly relaxing tissues like tendons. Few studies have applied T2 and T2* mapping to musculoskeletal imaging and to the rotator cuff tendons. Our objective was to analyze the T2 and T2* relaxation times from surgically repaired supraspinatus tendons and the effect of bone channeling. METHODS: One supraspinatus tendon of 112 adult female New Zealand white rabbits was surgically detached and repaired one week later. Rabbits were randomly assigned to channeling (n=64) or control (n=48) groups and harvested at 0, 1, 2, and 4 weeks. A 7T magnet was used for signal acquisition. For T2 mapping, a sagittal multi slice 2D multi-echo spin-echo (MESE) CPMG sequence with fat saturation was applied and T2* mapping was performed using a 3D UTE sequence. Magnetic resonance images from supraspinatus tendons were analyzed by two raters. Three regions of interest were manually drawn on the first T2-weighted dataset. For T2 and T2*, different ROI masks were generated to obtain relaxation times. RESULTS: T2-weighted maps but not T2*-weighted maps generated reliable signals for relaxation time measurement. Torn supraspinatus tendons had lower T2 than controls at the time of repair (20.0±3.4 vs. 25.6±3.9 ms; P<0.05). T2 increased at 1, 2 and 4 postoperative weeks: 22.7±3.1, 23.3±3.9 and 24.0±5.1 ms, respectively, and values were significantly different from contralateral supraspinatus tendons (24.8±3.1; 26.8±4.3 and 26.5±3.6 ms; all P<0.05). Bone channeling did not affect T2 (P>0.05). CONCLUSIONS: Supraspinatus tendons detached for 1 week had shorter T2 relaxation time compared to contralateral as measured with 7T MRI.

Rotator cuff anchor repair: Histological changes associated with the recovering mechanical properties in a rabbit model.

Rotator cuff anchor repair is an increasingly common surgical procedure but the failure rate remains high. In order to improve surgical outcomes, a better understanding of postrepair histological and cellular responses at the tendon-bone attachment site (enthesis) is needed. We examined operated shoulders from 42 New Zealand female white rabbits. The animals underwent unilateral supraspinatus detachment followed by anchor repair a week later. To assess enthesis reformation, fibrocartilage staining area and the number of chondrocytes or nonchondrocytes were quantified at 0, 1, 2, and 4 weeks postrepair. Using linear regression, we correlated these results with the load to failure and stiffness recorded during mechanical testing of the tendons. Fibrocartilage staining and chondrocyte number increased during the first 2 weeks of enthesis formation. Between 2 and 4 weeks, fibrocartilage staining plateaued while chondrocyte number decreased. The presence of nonchondrocytes remained similar between 0- and 1-week postrepair but then decreased abruptly at 2 weeks. There was a linear correlation between fibrocartilage staining area and load to failure as well as stiffness. Nonchondrocyte number negatively correlated with stiffness. Early plateau of fibrocartilage staining and decrease in chondrocytes between 2 and 4 weeks postrepair suggest a blunted enthesis formation response in our animal model.

Six degrees head-down tilt bed rest caused low-grade hemolysis: a prospective randomized clinical trial.

This study aimed to measure hemolysis before, during and after 60 days of the ground-based spaceflight analog bed rest and the effect of a nutritional intervention through a prospective randomized clinical trial. Twenty male participants were hospitalized for 88 days comprised of 14 days of ambulatory baseline, 60 days of 6° head-down tilt bed rest and 14 days of reambulation. Ten participants each received a control diet or daily polyphenol associated with omega-3, vitamin E, and selenium supplements. The primary outcome was endogenous carbon monoxide (CO) elimination measured by gas chromatography. Hemolysis was also measured with serial bilirubin, iron, transferrin saturation blood levels and serial 3-day stool collections were used to measure urobilinoid excretion using photometry. Total hemoglobin mass (tHb) was measured using CO-rebreathing. CO elimination increased after 5, 11, 30, and 57 days of bed rest: +289 ppb (95% CI 101-477 ppb; p = 0.004), +253 ppb (78-427 ppb; p = 0.007), +193 ppb (89-298 ppb; p = 0.001) and +858 ppb (670-1046 ppb; p < 0.000), respectively, compared to baseline. Bilirubin increased after 20 and 49 days of bed rest +0.8 mg/l (p = 0.013) and +1.1 mg/l (p = 0.012), respectively; and iron increased after 20 days of bed rest +10.5 µg/dl (p = 0.032). The nutritional intervention did not change CO elimination. THb was lower after 60 days of bed rest -0.9 g/kg (p = 0.001). Bed rest enhanced hemolysis as measured through all three by-products of heme oxygenase. Ongoing enhanced hemolysis over 60 days contributed to a 10% decrease in tHb mass. Modulation of red blood cell control towards increased hemolysis may be an important mechanism causing anemia in astronauts.

Supraspinatus tendon transosseous vs anchor repair surgery: a comparative study of mechanical recovery in the rabbit.

BACKGROUND: Supraspinatus (SSP) tendon ruptures requiring surgical repair are common. Arthroscopic suture anchor fixation has gradually replaced transosseous repair in supraspinatus tendon tear. Our objective was to compare mechanical properties between transosseous and anchor supraspinatus repair in the first 6 postoperative weeks in a rabbit model. METHODS: One hundred and fifty-two rabbits had one supraspinatus tendon repaired either with an anchor suture 1 week after detachment or with transosseous sutures. Rabbits were euthanized at 0, 1, 2, 4 or 6 postoperative weeks. Experimental and contralateral tendons (304 tendons) were mechanically tested to failure. Data are expressed as percent of contralateral. RESULTS: Anchor repair had higher loads to failure compared to transosseous repair, at immediate repair (week 0, 52 ± 21% vs 25 ± 17%, respectively; p = 0.004) and at 1 postoperative week (64 ± 32% vs 28 ± 10%; p = 0.003) with no difference after 2 weeks. There was no difference in stiffness. Transosseous repairs showed higher rates of midsubstance failures compared to anchor repairs at 1 (p = 0.004) and 2 postoperative weeks (p < 0.001). Both transosseous and anchor repairs restored supraspinatus mechanical properties after 4 postoperative weeks. CONCLUSION: Anchor repair provided better initial tensile strength while transosseous repair led to a faster normalization (namely, midsubstance) of the mode of failure. Research to optimize supraspinatus repair may need to consider the advantages from both surgical approaches.

Glenoid exposure in shoulder arthroplasty: the role of soft tissue releases.

BACKGROUND: The deltopectoral approach is commonly used in shoulder arthroplasty. Various soft tissue releases can be performed to obtain adequate glenoid exposure, but their effectiveness is not known. The purpose of this study was to (1) quantify the effects of various releases on the amount of glenoid surface area exposure and (2) determine if common soft tissue releases performed about the shoulder significantly improve exposure of the glenoid. METHODS: A standard deltopectoral approach was used on cadaveric shoulders (n=8) in the beach chair position. The releases performed were as follows: long head of biceps, pectoralis major tendon, inferior capsule, and posterior capsule. Following each release, a custom-designed jig was used to mark the exposed glenoid surface. The glenoid was then digitized using a 3D surface scanner to quantify the exposed surface area with each release. RESULTS: The mean glenoid surface area exposure prior to any releases was 57% (SD 8%). Following release of the long head of biceps, exposure increased to 69% (SD 10%). The exposed area was increased to 83% (SD 6%) with release of the pectoralis major, and 93% (SD 2%) with inferior capsule. The entire glenoid was exposed following posterior capsule release. CONCLUSIONS: Release of the long head of biceps, pectoralis major, and inferior and posterior capsule all independently led to significant increases in glenoid surface exposure in the deltopectoral approach. Mean surface area exposed with all 3 releases was 93%. Although posterior capsular release improved exposure, the results of this study suggest that this is rarely necessary.

Measuring Human Hemolysis Clinically and in Extreme Environments Using Endogenous Carbon Monoxide Elimination.

The measure of hemolysis in humans is clinically important. Here we describe methods using a gas chromatograph equipped with a reduction gas detector to detect the human analyte carbon monoxide (CO) that were developed for the extreme environment of the International Space Station. These methods can be adapted to in-hospital use for clinical care with characteristics that may surpass existing measures of hemolysis. We demonstrate improved performance over previous-generation methods in terms of reproducibility, accuracy, control for physical and intervening factors to quantitatively assess hemolysis rates at unprecedented levels. The presented measure of hemolysis using CO elimination is based on a different physiological approach that can complement and augment existing detection tools. In addition to their suitability for extreme environments, the methods present distinctive advantages over existing markers for the diagnosis, monitoring and response to treatment of hemolytic anemia. These methods have the potential to fulfill a wide range of research and clinical applications.

Early femoral component migration: comparing the anterior and posterior approach to the hip.

PURPOSE: Early femoral component migration is a useful indicator for identifying implants at risk of failure due to aseptic loosening. The goal of this retrospective study was to identify if anterior approach (AA) treated hips are at a higher risk of failure due to aseptic loosening caused by early migration compared to hips operated on using the traditional posterior approach (PA). METHODS: A total of 388 hips were included in this study, 139 AA and 249 PA treated hips. Femoral component migration was evaluated using EBRA-FCA and radiographs were assessed for radiolucency at latest follow-up. Preoperative and 2-year clinical outcomes were reported. RESULTS: The 1- and 2-year migration rates (mm/year), and total migration (mm) at 2-year follow-up were comparable between AA and PA hips, respectively: 0.52 versus 0.41, 0.18 versus 0.19, and 0.64 versus 0.63 (all p > 0.05). Though not statistically significant, a higher percentage of AA hips passed 2-year total migration thresholds that have been associated with aseptic loosening compared to PA hips: 25.4% versus 16.5% for 1.5 mm threshold, and 11.3% versus 4.1% for the 2.7 mm threshold. Migration was not associated with the presence of radiolucent lines. All clinical outcomes improved significantly between preoperative and 2-year follow-up. CONCLUSIONS: There was no association between the AA and any significant increase in femoral component migration. A higher percentage of AA hips exceeded the migration thresholds associated aseptic loosening; however, these stems had no other indications of instability and therefore suggests that this may be a difference in migration pattern.

Lateral Trochlear Ridge: A Non-Articulating Zone for Anterior-to-Posterior Screw Placement in Fractures Involving the Capitellum and Trochlea.

BACKGROUND: Coronal shear fractures of the distal aspect of the humerus that involve the capitellum and the trochlea are rare; nevertheless, they are difficult to treat because of the complex fracture patterns and osteochondral nature of the fragments, limiting optimal screw placement. The use of anterior-to-posterior screw fixation by a lag technique (without countersinking) could potentially improve the strength of the construct. Our primary research question was to anatomically determine if there is a non-articulating zone for screw placement along the anterior aspect of the lateral trochlear ridge (aLTR) throughout normal elbow range of motion. METHODS: Eight fresh-frozen cadaveric elbows were used. The region of interest was defined with 3 polymeric pins inserted in the inferior, middle, and superior-most aspects of the aLTR of each elbow, with use of an extensor digitorum communis (EDC) split approach. The elbows were then mounted on a magnetic resonance imaging (MRI)-compatible compression frame and subjected to high-resolution 7-T MRI at 90°, 120°, and 145° of flexion (positions of potential impingement), and at neutral and maximal pronation and maximal supination for each position of flexion. Portions of the aLTR that had free adjacent space were identified using the sagittal and coronal scans. This non-articulating region was identified as the "non-articulating zone" (NAZ). RESULTS: The NAZ was found to encompass the proximal 38.2% (range, 30.2% to 48.9%) of the aLTR, measuring, on average, 5.2 mm in width. It was consistently located either directly adjacent to the apex of the ridge or just medial to it. The distal 61.8% of the aLTR articulated with either the ulna or the radial head in some of the elbows. CONCLUSIONS: Our results suggest that there is a portion of the aLTR that, despite being covered with articular cartilage, is non-articulating throughout normal elbow range of motion. CLINICAL RELEVANCE: In situations in which headless anterior-to-posterior and posterior-to-anterior screw insertion results in inadequate fixation of capitellar-trochlear fractures, anterior-to-posterior lag screw instrumentation along the non-articulating portion of the aLTR may provide a location for additional fixation in some patients. However, because of variation between patients, each case must be individualized.

Comparing In Vivo Performance of Two Highly Cross-Linked Polyethylene Thermal Treatments: Remelting vs Annealing in Acetabular Liners.

BACKGROUND: The introduction of highly cross-linked polyethylene (HXLPE) acetabular liners has greatly improved the wear performance of metal-on-PE bearing surfaces used in total hip arthroplasty. Changing the sterilization environment and adding thermal treatments, such as remelting or annealing, were introduced to limit on-shelf and in vivo oxidation of cross-linked liners. This study compares the wear properties of the remelted A-CLASS (MicroPort) HXLPE liner to a sequentially annealed HXLPE. METHODS: This retrospective study assessed linear and volumetric wear rates using Martell Hip Analysis Suite, and clinical performance through incidences of revision surgeries. A total of 80 remelted and 53 annealed liners were included in the wear analysis. All hips were reviewed for revisions. RESULTS: There were no significant differences in steady-state linear or volumetric wear rates for remelted and annealed liners, 0.01 (-0.07 to 0.14) vs -0.01 (-0.11 to 0.1) mm/y (P = .28) and -1.03 (-30.99 to 45.43) vs -1.31 (-32.23 to 23.70) mm3/y (P = .30), respectively. Both cohorts were below the 0.1 mm/y linear wear threshold. The wear rates for patients with femoral head sizes ≥36 mm were not significantly different than those with 32 and 28 mm femoral head sizes (P = .60). Similarly, wear rates for patients with an excessively vertical acetabular component (>50°) were not significantly different than those with standard acetabular component orientations (P = .97). No hips were revised due to liner-related complications. CONCLUSION: The wear rates of the A-CLASS remelted HXLPE acetabular liner wear rates were comparable to those of a sequentially annealed HXLPE. Further long-term studies are required to ensure acceptable resistance to fatigue and in vivo oxidation.

Posterior malleolus exposure.

Objectives: Posterior malleolus (PM) fractures are common in rotational ankle injuries, tibial plafond fractures, and distal third tibia fractures. Surgical indications continue to evolve as we improve our understanding of ankle and syndesmotic stability. These fractures remain technically challenging with respect to both exposure and fixation. Our biomechanical cadaveric study compared posterolateral versus modified posteromedial surgical approaches to define the following: maximal surface area exposed, and maximal screw trajectory obtainable for fixation. Methods: Twelve fresh-frozen cadaver limbs were thawed at room temperature. Posterolateral and modified posteromedial approaches were performed on each limb. Margins of exposure were marked. A 2.5 mm drill was advanced at the extreme medial and lateral extents of each exposure, standardized at 1 cm proximal to the joint line and perpendicular to the bone. Computed tomography (CT) scans were performed to identify the maximal trajectory. Limbs were stripped of soft tissue, and the exposed bony surface area was measured using a validated laser surface-scanning technique. Results: The modified posteromedial approach allowed for a larger exposed surface area compared to the posterolateral exposure (median 99% vs 64%, respectively; P < .05). The modified posteromedial approach allowed for instrumentation of up to a median of 77% of the posterior distal tibia as opposed to 46% through the posterolateral approach (P < .05). Conclusion: The modified posteromedial approach allowed for increased exposure and wider access for instrumentation of the PM when compared to the posterolateral approach. We advocate use of this approach when addressing complex PM fractures, in particular the Haraguchi type 2 fracture pattern.

Fixation of Anteromedial Coronoid Facet Fractures: A Biomechanical Evaluation of Plated Versus Screw Constructs.

OBJECTIVE: To examine the stability of plate (locking and non-) versus screw constructs in the fixation of these fractures. METHODS: An anteromedial coronoid facet fracture (OTA/AO type 21-B1, O'Driscoll type 2, subtype 3) was simulated in 24 synthetic ulna bones that were then assigned to 3 fracture fixation groups: non-locking plate, locking plate (LP), or screw fixation. Each construct was first cycled in tension (through a simulated medial collateral ligament) and then in compression. They were then loaded to failure (displacement >2 mm). Fracture fragment displacement was recorded with an optical tracking system. RESULTS: During tension testing, a mean maximum fragment displacement of 12 ± 13 and 14 ± 9 µm was seen in the locking and non-locking constructs, respectively. There was no difference in fragment motion between the plated constructs. All screw-only fixed constructs failed during the tension protocol. During compression testing, the mean maximum fragment displacement for the screw-only construct (64 ± 79 µm) was significantly greater than locking (9 ± 5 µm) and non-locking constructs (10 ± 9 µm). During load to failure testing, the maximum load to failure in the screw-only group (316 ± 83 N) was significantly lower than locking (650.4 ± 107 N) and non-locking constructs (550 ± 76 N). There was no difference in load to failure between the plated groups. CONCLUSION: Fixation of anteromedial coronoid fractures (type 2, subtype 3) is best achieved with a plating technique. Although LPs had greater stiffness, they did not offer any advantage over conventional non-LPs with respect to fracture fragment displacement in this study. CLINICAL RELEVANCE: Isolated screw fixation showed inferior stability when compared with plate constructs for these fractures. This could result in loss of fracture reduction leading to instability and posttraumatic arthrosis.

Supraspinatus tendon repair using anchors: a biomechanical evaluation in the rabbit.

BACKGROUND: Arthroscopic rotator cuff repairs are mostly secured with suture anchors and often supplemented by footprint decortication. The objectives of this study were to characterize the strength of bone-tendon healing following anchor repair and assess the effect of channeling the supraspinatus (SSP) humeral footprint 1 week ahead of reattachment surgery. METHODS: One hundred twelve rabbits underwent unilateral detachment of one SSP tendon and were randomly assigned to two groups: channeling the footprint at time of detachment and no channeling. One week later, reattachment was performed using an anchor. The repaired and contralateral shoulders were harvested at 0, 1, 2, or 4 weeks after repair and mechanically tested to failure. Outcome measures included load at failure, stiffness, and site of failure. RESULTS: Anchor fixation had a mean load at failure of 81 ± 32 N and a stiffness of 27 ± 9 N/mm immediately after repair compared to 166 ± 47 N and 66 ± 13 N/mm in the contralateral (both p < 0.05). Mechanical recovery of the reattached SSP tendon was achieved after 4 weeks (221 ± 73 N, 206 ± 59 N, and 198 ± 49 N in the channeling, no channeling, and contralateral groups, respectively, p > 0.05). The dominant site of failure shifted from the footprint at 0/1 week to bone avulsion/mid-substance tear at 4 weeks (p < 0.05). There were no differences in outcomes between the channeling and no channeling groups. CONCLUSIONS: This study is the first of its kind to provide quantitative data on the mechanical properties of the enthesis following anchor repair in a rabbit model. Anchor repair led to rapid and complete restoration of SSP mechanical properties. Further evidence is needed before recommending channeling ahead of repair surgery.

Imaging of the rabbit supraspinatus enthesis at 7 Tesla: a 4-week time course after repair surgery and effect of channeling.

PURPOSE: To image the supraspinatus enthesis reformation of rabbit shoulders by magnetic resonance at 7 Tesla (T) using T2 mapping after surgical repair and to assess the effects of channeling aimed at enhancing enthesis reformation. MATERIALS AND METHODS: In 112 rabbits, the distal supraspinatus (SSP) tendon was unilaterally detached and reattached after 1 week. At the first surgery, channeling was performed at the footprint in 64 rabbits. At the second surgery, the SSP tendon of all rabbits was re-attached to the greater tuberosity. The shoulders were harvested at 0, 1, 2, or 4 weeks after the repair surgery and were imaged at 7T. Quantitative T2 mapping was performed using multi slice two-dimensional multi-echo spin-echo sequence with fat saturation. Enthesis regions of interests were drawn on three slices at the footprint to measure T2 relaxation times. RESULTS: Tendon repair (F(2, 218) = 44; P < 2.2e-16) and postoperative duration (F(3, 218) = 4.8; P = 0.006) both affected significantly the T2 values while channeling had no significant effect. For the time effect, the only pair with a statistical difference was the 0-week and 4-week for the channeling groups (P = 0.023). CONCLUSION: Enthesis reformation early after surgical repair of the SSP distal tendon was characterized by increasing T2 values. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:461-467.

The Effect of Varying Tension of a Suture Button Construct in Fixation of the Tibiofibular Syndesmosis-Evaluation Using Stress Computed Tomography.

BACKGROUND/PURPOSE: There have been no studies assessing the optimal biomechanical tension of suture button constructs. The purpose of this study was to assess optimal tensioning of suture button fixation and its ability to maintain reduction under loaded conditions using a stress computed tomography (CT) model. METHODS: Ten cadaveric lower limbs disarticulated at the knee were used. The limbs were placed in a modified ankle load frame that allowed for the application of sustained torsional axial or combined torsional/axial loads. The syndesmosis and the deep deltoid ligaments complex were sectioned and the limbs were randomized to receive a suture button construct tightened at 4, 8, or 12 kg. The specimens were loaded under the 3 loading scenarios with CT scans performed after each and at the conclusion of testing. Multiple measurements of translation and rotation were compared with baseline CT scan taken before sectioning. RESULTS: Significant lateral (maximum 5.26 mm) and posterior translation (maximum 6.42 mm) and external rotation (maximum 11.71 degrees) was noted with the 4 kg repair. Significant translation was also seen with both the 8 and the 12 kg repairs; however, the incidence was less than with the 4 kg repair. Significant overcompression (ML = 1.69 mm, B = 2.69 mm) was noted with the 12 kg repair and also with the 8 kg repair (B = 2.01 mm). CONCLUSION: Suture button constructs must be appropriately tensioned to maintain reduction and re-approximate the degree of physiological motion at the distal tibiofibular joint. These constructs also demonstrate overcompression of the syndesmosis; however, the clinical effect of this remains to be determined.

Effects of hip implant modular neck material and assembly method on fatigue life and distraction force.

Hip implant neck fractures and adverse tissue reactions associated with fretting-corrosion damage at modular interfaces are a major source of concern. Therefore, there is an urgent clinical need to develop accurate in vitro test procedures to better understand, predict and prevent in vivo implant failures. This study aimed to simulate in vivo fatigue fracture and distraction of modular necks in an in vitro setting, and to assess the effects of neck material (Ti6Al4V vs. CoCrMo) and assembly method (hand vs. impact) on the fatigue life and distraction of the necks. Fatigue tests were performed on the cementless PROFEMUR® Total Hip Modular Neck System under two different loads and number of cycles: 2.3 kN for 5 million cycles, and 7.0 kN for 1.3 million cycles. The developed in vitro simulation setup successfully reproduced in vivo modular neck fracture mode and location. Neck failure occurred at the neck-stem taper and the fracture ran from the distal lateral neck surface to the proximal medial entry point of the neck into the stem. None of the necks failed under the 2.3 kN load. However, all hand-assembled Ti6Al4V necks failed under the 7.0 kN load. In contrast, none of the hand-assembled CoCrMo necks and impact-assembled necks (Ti6Al4V or CoCrMo) failed under this higher load. In conclusion, Ti6Al4V necks were more susceptible to fatigue failure than CoCrMo necks. In addition, impact assembly substantially improved the fatigue life of Ti6Al4V necks and also led to overall higher distraction forces for both neck materials. Overall, this study shows that the material and assembly method can affect the fatigue strength of modular necks. Finally, improper implant assembly during surgery may result in diminished modular neck survivability and increased failure rates. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2023-2030, 2017.

Lateral Elbow Exposures: The Extensor Digitorum Communis Split Compared with the Kocher Approach.

INTRODUCTION: In comparison with the frequently used modified Kocher approach, the extensor digitorum communis (EDC) splitting approach allows improved access to the anterior half of the radial head, which is most commonly fractured, while reducing the risk of iatrogenic injury to the lateral collateral ligament. STEP 1 MAKE THE INCISION MODIFIED KOCHER APPROACH: Make an oblique 7-cm lateral incision beginning at the proximal edge of the lateral epicondyle and extending distally over the center of the radial head toward the posterior ulnar border of the extensor carpi ulnaris muscle belly. STEP 2 DEVELOP THE INTERVAL BETWEEN THE ANCONEUS AND THE EXTENSOR CARPI ULNARIS: Identify and develop the intermuscular interval between the anconeus and the extensor carpi ulnaris. STEP 3 PERFORM THE LATERAL ELBOW CAPSULOTOMY: Longitudinally incise the lateral elbow capsule and annular ligament anterior to the lateral ulnar collateral ligament. STEP 4 THE EXTENDED MODIFIED KOCHER APPROACH: Extend the exposure by elevating the common extensor origin (extensor carpi radialis brevis, EDC, and extensor carpi ulnaris) proximally off the lateral epicondyle and reflect it anteriorly. STEP 5 MAKE THE INCISION EDC SPLITTING APPROACH: Make a longitudinal oblique 5 to 6-cm lateral incision beginning at the proximal edge of the lateral epicondyle and extending distally over the radial head toward the Lister tubercle. STEP 6 IDENTIFY AND SPLIT THE EDC: The EDC tendon is identified and bisected longitudinally starting proximally at its origin on the lateral epicondyle and extending 20 mm distally from the radiocapitellar joint. STEP 7 PERFORM THE LATERAL ELBOW CAPSULOTOMY: The annular ligament and joint capsule are then incised collinear with the EDC split anterior to the equator of the capitellum. STEP 8 EXTENDED EDC SPLITTING APPROACH: Extend the exposure by detaching the anterior half of the EDC tendon and the extensor carpi radialis brevis tendon from the lateral epicondyle. STEP 9 LAYERED CLOSURE: Perform an interrupted layered closure. RESULTS: In our recent cadaveric study, we quantitatively compared the modified Kocher and EDC splitting approaches in order to determine which provided the greatest exposure of the anterior aspect of the radial head, which is most commonly fractured.IndicationsContraindicationsPitfalls & Challenges.

Proper placement of the distal biceps tendon during repair improves supination strength--a biomechanical analysis.

BACKGROUND: Anatomic repair of the distal biceps tendon can be difficult to achieve. This study was designed to compare the effect of anatomic and nonanatomic repairs on forearm supination torque. A nonanatomic repair re-establishes the footprint radial and more anterior to the tuberosity apex, whereas an anatomic repair re-establishes the footprint ulnar and more posterior to the tuberosity apex. METHODS: Eight fresh frozen cadaver arms were surgically prepared and mounted on an elbow simulator. Controlled loads were applied to the long head and short head in positions of pronation, neutral, and supination. This was done with intact tendons and then repeated with repaired tendons that were repaired either anatomically (ulnar position) or nonanatomically (radial position). RESULTS: All anatomic repairs showed no difference compared with intact tendon measurements. In comparing anatomic and nonanatomic repairs, we found no differences in the supination torque when the forearm was in 45° of pronation. However, when the arm was in neutral rotation, we found that 15% less supination torque was generated by the nonanatomic repair. When the arm was tested in 45° of supination, we found that 40% less supination torque was generated in the nonanatomic repair (P = .01). CONCLUSION: This study supports the idea that an anatomic repair of the biceps tendon onto the ulnar side of the radial tuberosity is important. If the tendon is repaired too radially, the biceps will lose the cam effect and may not be able to generate full supination torque when the forearm is in neutral rotation or in supination.

Objective analysis of lateral elbow exposure with the extensor digitorum communis split compared with the Kocher interval.

BACKGROUND: The most widely used surgical approach to treat radial head fractures is through the Kocher interval. However, the extensor digitorum communis (EDC) splitting approach is thought to allow easier access to the anterior half of the radial head, which is more commonly fractured. The aim of this cadaveric study was to compare the osseous and articular surface areas visible through the EDC split and the Kocher interval. METHODS: Four approaches were used in fresh frozen cadaveric upper extremities: EDC splitting (n = 6), modified Kocher (n = 6), extended EDC splitting (n = 6), and extended modified Kocher (n = 4). For each approach, the osseous and articular surface areas visualized were outlined with use of a burr. Each elbow was then stripped of soft tissue and a digitized three-dimensional model was created with use of a surface scanning system. The visible surface area obtained with each approach was mapped and quantified with use of the markings created with the burr. RESULTS: The EDC splitting approach provided greater exposure of the anterior half of the radial head (median, 100%) compared with the modified Kocher approach (68%, p < 0.05). The extended modified Kocher and extended EDC splitting approaches provided comparable visualization of the distal aspect of the humerus, capitellum, radial head, and coronoid process. CONCLUSIONS: The results suggest that the EDC splitting approach provides more reliable visualization of the anterior half of the radial head while minimizing soft-tissue dissection and reducing the risk of iatrogenic injury to the lateral ulnar collateral ligament.

The effect of medial release of the distal patellar tendon insertion on lateral patella translation and residual insertion strength: a cadaveric study.

Patellar tendon avulsion is a risk with difficult exposure in a stiff knee, patella baja or previous tibial osteotomy. We sought to define a safe amount of release of the patellar tendon insertion for such cases. Eleven pairs of fresh frozen cadaveric lower limb specimens were acquired and randomized to either intact or partial release of the distal tibial insertion. Partial release of the tibial insertion of the tendon increased lateral exposure a mean 29% ± 15% (P = 0.002) while reducing ultimate strength to a mean of 80% that of the intact contralateral tendon. Measured patella release increased lateral patella translation and can be performed without risk of catastrophic rupture with basic activities of daily living following TKA.