Step-wise medial collateral ligament needle puncturing in extension leads to a safe and predictable reduction in medial compartment pressure during TKA.

PURPOSE: Medial soft tissue release in a varus deformity knee during total knee arthroplasty is essential for accurate balancing of the reconstruction. This study attempts to quantify the effect of sequential needle puncturing of the medial collateral ligament (MCL) using a pressure sensor insert (Verasense by OrthoSensor) and gap measurement under tension. METHODS: Cruciate-retaining arthroplasties were placed in 14 cadaveric knees. The MCL was elongated by step-wise perforation, in five sets of five perforations, with the use of an 18-gauge needle, followed by valgus stress. Following the fifth set of needle perforations, blade perforation was performed on the remaining tense fibers of the MCL. Following each step-wise perforation, corresponding medial compartment pressures and gap measurements under tension were recorded. RESULTS: Sensor measurements correlated closely with step-wise tissue release (R = 0.73, p < 0.0001), and a significant decrease in pressure was found in early needle puncturing (mean 49 N after 5, 83 N after 15, p values < 0.05), although changes diminished at later stages of needle perforation (90 N after 20). Gap measurement demonstrated small gradual changes with early puncturing, but showed significant opening in the later stages of release. There was minimal variation in pressure or gap measurements in flexion versus extension. This finding suggests that MCL needle puncture will not lead to unequal gaps between flexion and extension. There were no cases of MCL over-release after 15 punctures, one case after 20 punctures, and three after blade perforation. CONCLUSION: Needle puncturing of the MCL in extension for up to 15 punctures can be a safe and predictable way to achieve medial opening when balancing a varus knee during TKA as demonstrated in this cadaveric model. Blade perforation should be used with caution to avoid over-release. The needle puncture method can be used by surgeons to achieve reliable reductions in medial compartment pressures, to help achieve a balanced TKA, with minimal risk of over-release.

Inter- and intra-observer agreement of femoroacetabular impingement (FAI) parameters comparing plain radiographs and advanced, 3D computed tomographic (CT)-generated hip models in a surgical patient cohort.

PURPOSE: The purpose of our study was to investigate whether advanced, 3D computed tomographic (CT)-generated hip models improves inter-and intra-observer agreement when compared to plain radiographs in identifying femoroacetabular impingement (FAI) morphology. METHODS: Eight consecutive patients who underwent surgery for FAI pathology were selected for this study. Preoperative CT scan image data were used to create high resolution, 3D hip reconstruction models. Four observers (two attending hip surgeons and radiologists) performed a blinded review of preselected radiographs and 3D CT hip models. Alpha and lateral center-edge angle measurements, location of cam lesion and the presence of a "crossover sign" were assessed. Inter- and intra-observer agreement was determined by calculating the intra-class correlation coefficients (ICC) or kappa coefficients to evaluate agreement for categorical variables. RESULTS: The parameter that demonstrated the highest and poorest inter-observer agreement was the presence of a "crossover sign" using 3D CT-generated high resolution hip models (ICC = 0.76, p = 0.00) and anteroposterior pelvis radiography, respectively (ICC = 0.20, p = 0.02). Alpha angle values were significantly higher using plain radiographs when compared to 3D hip reconstruction models (61.1° ± 10.4° versus 55.4° ± 14.4°, p = 0.003). Furthermore, when compared to radiographs, 3D hip reconstruction models demonstrated significantly higher intra-observer agreement (ICC = 0.856 versus 0.405, p = 0.005) when determining the presence of a "crossover sign". CONCLUSIONS: Our findings were suggestive that for most commonly used FAI morphology parameters, CT-generated hip models demonstrated little benefit over plain radiographs in improving inter-observer agreement among providers. LEVEL OF EVIDENCE: III.

A new method for achieving compression in hindfoot arthrodesis.

BACKGROUND: When performing hindfoot arthodeses, one goal of fixation is often to achieve compression across the joint. Traditional lag screws are applied eccentrically, providing compression more on the edge of the fusion. A new technique, using a post in one bone and a lag screw through the post to the other bone, may offer better compression across more of the joint. METHODS: There are three parts to this study comparing a post-and-screw construct to traditional lag screws. Synthetic bone models, representative of the talonavicular joint, were created and assessed for biomechanical measures of compression. Next, the post-and-screw construct was tested in cadavers, under conditions representing early weight bearing after arthrodesis surgery. Finally, 18 patients who had a talonavicular fusion with a post-and-screw construct with one surgeon were compared to the previous 18 patients fixed with traditional screws. RESULTS: In the synthetic bone model, the post-and-screw construct brought the centre of compression closer to the centre of the joint, suggesting compression was less eccentric. Neither traditional screws nor the post-and-screw construct were sufficiently strong to resist early weight bearing forces in cadaver specimens. In the clinical comparison, four patients had a painful nonunion when fixed with traditional screws, compared to none in the post-and-screw construct. CONCLUSIONS: A post-and-screw construct spreads the forces of compression more uniformly across an arthrodesis, even when placed eccentrically. Although not all the biomechanical measures were superior, the post-and-screw construct achieved higher levels of successful fusion in patients. This technology may offer improved outcomes in some clinical scenarios and deserves further study. LEVEL OF EVIDENCE: Level 3.

Rotator cuff repair augmentation with local autogenous bone marrow via humeral cannulation in a rat model.

BACKGROUND: Growth factors have been shown to improve healing after rotator cuff repair. Bone marrow is a potential vehicle for growth factor augmentation, yet methods of delivering marrow to cuff repair sites are still under-researched. We hypothesized that a cannulated humeral implant would deliver local bone marrow and thereby improve healing in a rat model. METHODS: Twenty-eight rats underwent bilateral rotator cuff injury and repair. Each rat acted as its own control, randomized to a cannulated humeral implant in one shoulder and a solid implant in the other. Rats were euthanized at 4 and 8 weeks to create 4 time-treatment cohorts. Tendon healing was evaluated by dimensional measurements, biomechanical testing, and histology. RESULTS: Tendon thickness, all biomechanical measures, and semi-quantitative histologic scores improved over time (P < .05) but not with treatment. The most common site of biomechanical tendon failure was midsubstance in the 8-week cannulated cohort and at the tendon footprint in the other 3 cohorts. Intraluminal bone growth was evident in all cannulated implants. CONCLUSIONS: Humeral cannulation did not quantifiably improve tendon-to-bone healing in a rat model. The diminutive size of implants in rats, however, may have prevented sufficient delivery of local autogenous bone marrow; hence, further study in a larger animal is recommended.

Glenoid implant orientation and cement failure in total shoulder arthroplasty: a finite element analysis.

BACKGROUND: To minimize glenoid implant loosening in total shoulder arthroplasty (TSA), the ideal surgical procedure achieves correction to neutral version, complete implant-bone contact, and bone stock preservation. These goals, however, are not always achievable, and guidelines to prioritize their impact are not well established. The purpose of this study was to investigate how the degree of glenoid correction affects potential cement failure. METHODS: Eight patient-specific computer models were created for 4 TSA scenarios with different permutations of retroversion correction and implant-bone contact. Two bone models were used: a homogeneous cortical bone model and a heterogeneous cortical-trabecular bone model. A 750-N load was simulated, and cement stress was calculated. The risk of cement mantle fracture was reported as the percentage of cement stress exceeding the material endurance limit. RESULTS: Orienting the glenoid implant in retroversion resulted in the highest risk of cement fracture in a homogeneous bone model (P < .05). In the heterogeneous bone model, complete correction resulted in the highest risk of failure (P = .0028). A positive correlation (ρ = 0.901) was found between the risk of cement failure and amount of exposed trabecular bone. CONCLUSIONS: Incorporating trabecular bone into the model changed the effect of implant orientation on cement failure. As exposed trabecular bone increased, the risk of cement fracture increased. This may be due to shifting the load-bearing support underneath the cement from cortical bone to trabecular bone.

Glenoid articular conformity affects stress distributions in total shoulder arthroplasty.

BACKGROUND: The stress applied to the glenoid component in total shoulder arthroplasty (TSA) remains an important concern because of the risk of wear and loosening. The purpose of this study was to determine the stress pattern in the glenoid component with 3 different surface designs. METHODS: Computer models of 9 scapulae of patients scheduled for TSA were created from computerized tomography images. Each glenoid was virtually reamed, and 3 different glenoid component designs (conforming, nonconforming, and hybrid) were placed. Using finite element analysis, superior translation of the humeral head was modeled. Maximum stress and shear stress were measured at 3 different locations in the glenoid component: center, transition, and superior regions. RESULTS: All 3 designs showed a similar level of maximum stress at the center and transition regions, while the maximum stress at the superior periphery was significantly higher in the conforming design than in the other 2 designs (P = .0017). The conforming design showed significantly higher shear stress at the superior periphery (P < .0001). DISCUSSION: Stress from periphery loading is higher than from the center and transition region regardless of component design and is highest in the conforming design. The stress at the transition region of the hybrid design was not higher than the other 2 designs. The hybrid design has favorable characteristics based on its low stress at the periphery and greater contact area with the humeral head at the center. LEVEL OF EVIDENCE: Basic Science Study, Biomechanical Computer Simulation Study.

Glenoid morphology after reaming in computer-simulated total shoulder arthroplasty.

BACKGROUND: The relationships between reaming parameters for glenoid-implant surface area and bone loss in total shoulder arthroplasty have not been well established. The hypotheses of this study are: (1) for large version corrections, a large reaming depth of 5 mm is not sufficient to obtain complete glenoid implant contact; (2) glenoid bone is removed in a linear proportion with reaming depth; and (3) initial reamer placement has no effect on glenoid bone removal. METHODS: Ten computer models from computed tomography scans of patients with advanced osteoarthritis were created for computer-simulated reaming as performed during total shoulder arthroplasty. Reaming variables studied included reaming depth, reamer placement, and version correction. The resulting reamed glenoid surface area available for implantation and bone volume removed were calculated for each permutation. RESULTS: Reamed surface area significantly increased with larger depths of reaming (P < .0001) and smaller version corrections (P < .0001). Bone volume removed and reaming depth had a strong quadratic relationship (r(2) = 0.999). With off-center reamer placement, volume removed when deviating in the posterior direction was significantly greater than when deviating in the anterior, superior, or inferior direction (P < .05). CONCLUSION: Performing smaller version corrections allows for greater attainable implant-bone surface contact because increasing reaming depth results in small increases in conforming surface area but large losses in glenoid bone stock. Bone volume removed was most sensitive to off-center position errors in the posterior direction.

Percutaneous Fixation of Unstable Proximal Phalanx Fractures: A Biomechanical Study.

BACKGROUND: Unstable extra-articular proximal phalanx fractures are common injuries to the hand that are often treated by closed reduction and percutaneous pinning. Fracture-induced shortening of the proximal phalanx leads to an extensor lag at the proximal interphalangeal joint. We describe a biomechanical study in cadaver hands to compare the ability of each of three different pin configurations to resist shortening in unstable fractures. METHODS: Seventeen fresh frozen hands were disarticulated at the proximal ends of the metacarpals. The second, third, and fourth proximal phalanges were tested. A 5-mm section of bone was resected from the mid-shaft of proximal phalanx to simulate an unstable fracture. Three techniques were employed and randomized for each finger: transmetacarpophalangeal joint pinning using 1 or 2 Kirschner wires (K-wires) and periarticular cross pinning using 2 K-wires. Compressive axial loads and energy at 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm of subsidence were examined. RESULTS: The forces and energy required to shorten the finger for each amount of subsidence were similar for all 3 pinning techniques and for all 3 finger types. Greater amounts of shortening were found to require larger forces. CONCLUSION: Closed reduction and percutaneous pinning using any of the presented techniques is an adequate method of treatment for unstable proximal phalanx fractures. All of the techniques were equivalent in their ability to resist axial loading, regardless of the complexity of technique, the number of pins used, or finger that was pinned.

Perioperative polyphenon E- and siliphos-inhibited colorectal tumor growth and metastases without impairment of gastric or abdominal wound healing in mouse models.

INTRODUCTION: Perioperative anticancer therapy that does not impair wound healing is needed to counter the persistent proangiogenic plasma compositional changes that occur after colorectal resection. Polyphenon E (PolyE), a green tea derivative (main component EGCG), and Siliphos (main component silibinin), from the milk thistle plant, both have antitumor effects. This study assessed the impact of PolyE/Siliphos (PES) on wound healing and the growth of CT-26 colon cancer in several murine models. METHODS: One wound healing and three tumor studies were performed. Tumor Study (TS)1 assessed the impact of PES on subcutaneous tumor growth, whereas TS2 assessed PES's impact on subcutaneous growth when given pre- and post-CO(2) pneumoperitoneum (pneumo), sham laparotomy, or anesthesia alone. TS3 determined the ability of PES to limit hepatic metastases (mets) after portal venous injection of tumor cells. In the final study, laparotomy and gastrotomy wound healing were assessed several ways. BALB/c mice were used for all studies. The drugs were given via drinking water (PolyE) and gavage (Siliphos), daily, for 7-9 days preprocedure and for 7-21 days postoperatively. Tumor mass, number/size of hepatic mets, and proliferation and apoptosis rates were assessed. The abdominal breaking strength and energy to failure were measured postmortem as was gastric bursting pressures. RESULTS: PES significantly inhibited subcutaneous growth in the nonoperative setting. PES also significantly decreased the number/size of liver mets when given perioperatively. Abdominal wound breaking strength, energy to wound failure, and collagen content were not altered by PES; gastrotomy bursting strength also was not affected by PES. Neither drug alone had a significant impact on tumor growth. CONCLUSIONS: The PES combination inhibited subcutaneous and hepatic tumor growth yet did not impair wound healing. PES holds promise as a perioperative anticancer therapy.

Scaphoid excision and 4-bone arthrodesis versus proximal row carpectomy: a comparison of contact biomechanics.

PURPOSE: We compare scaphoid excision and 4-bone arthrodesis (FBA) with proximal row carpectomy (PRC) in terms of contact pressure, area, and location. METHODS: Six cadaveric forearms underwent simulated FBA with K-wires. We measured pressures in the radiocarpal joint with Fuji contact film after we applied a 200-N load via the wrist tendons with the wrist in neutral, flexion, and extension. We repeated the experiment after excising the lunate and triquetrum, to create a PRC in the same specimens. RESULTS: Contact pressure in the PRC wrist was significantly greater, by 25%, compared with the FBA wrist for all wrist positions. The PRC wrist had a significantly smaller contact area, by 43%, compared with the FBA wrist. In the FBA wrist, lunate contact was more dorsal in flexion but more volar in extension. In the PRC wrist, capitate contact was more dorsal and radial in flexion, whereas the contact was more volar and ulnar in extension. Comparing contact location, FBA contact was significantly more ulnar than PRC contact in wrist flexion. We found no significant difference in contact translation (the distance between the contact locations in the positions of wrist flexion and extension) for the lunate in FBA or the capitate in PRC. CONCLUSIONS: The FBA wrist has significantly lower contact pressure (P < .001), greater contact area (P < .001), and equal contact translation compared with the PRC wrist. These qualities may make FBA less susceptible to degeneration over time. By advancing our understanding of the biomechanics of both wrist procedures, we may better tailor them to the individual patient. CLINICAL RELEVANCE: Current biomechanical evidence is lacking for common motion-preserving procedures for wrist arthritis. Comparing contact pressure, area, and location provides a biomechanical basis of our clinical understanding of these surgeries.

Reverse total shoulder arthroplasty for cuff tear arthropathy: the clinical effect of deltoid lengthening and center of rotation medialization.

BACKGROUND: Reverse total shoulder arthroplasty (RSA) for cuff tear arthropathy improves shoulder function and reduces pain. Implant position and soft tissue balancing are important factors to optimize outcome. Tensioning the deltoid and increasing the deltoid moment arm by medializing the center of rotation are biomechanically advantageous. The purpose of this study was to correlate RSA functional outcomes with deltoid lengthening and center of rotation medialization. MATERIALS AND METHODS: This prospective cohort study enrolled 49 consecutive patients who underwent RSA for cuff tear arthropathy. Preoperative and serial postoperative physical examinations, radiographs, and American Shoulder and Elbow Surgeons and Simple Shoulder Test scores were evaluated. Deltoid lengthening and medialization of the center of rotation were measured radiographically and correlated with functional outcome scores, range of motion, and complications. RESULTS: At final follow-up (average, 16 ± 10 months), 37 of 49 patients (76%) were available for analysis. Deltoid lengthening (average, 21 ± 10 mm) correlated significantly (P = .002) with superior active forward elevation (average, 144° ± 19°). Medialization of the center of rotation (average, 18 ± 8 mm) did not correlate with active forward elevation or subjective outcomes. Deltoid lengthening that achieved an acromion-greater tuberosity distance exceeding 38 mm had a 90% positive predictive value of obtaining 135° of active forward elevation. Two patients (4%) required revision surgery, and 68% of patients developed scapular notching (average grade, 1.3 ± 1.2) at final follow-up. CONCLUSION: Deltoid lengthening improves active forward elevation after RSA for cuff tear arthropathy.

Perioperative polyphenon E, a green tea extract, does not affect the wound complication rate in mice after sham laparotomy yet has an inhibitory effect on wound healing.

INTRODUCTION: Major surgery is associated with physiologic alterations that may promote tumor growth, and catechins in green tea may inhibit tumor growth. This study's aim was to assess the impact of a green tea extract on laparotomy wound healing in mice. METHODS: Mice were randomized to daily oral catechins solution (n = 25) or placebo (n = 20), underwent sham laparotomy after 10 days, and were sacrificed on postoperative day 7 or 21. The peak force and total energy required to rupture the abdominal wall wound, wound collagen content, and histology were assessed. RESULTS: There were no wound complications in either group, and mean peak wound rupture forces and collagen concentration were similar. Mean energy was lower and more fibroblast proliferation was found in the treatment group on postoperative day 21. CONCLUSIONS: These results suggest that catechins has only mild clinically significant adverse effect on wound healing, and its perioperative use warrants further study.

An anatomic and biomechanical study of the oblique retinacular ligament and its role in finger extension.

PURPOSE: To analyze the anatomy and contribution of the oblique retinacular ligament (ORL) to distal interphalangeal (DIP) joint extension force with varying angles of proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joint flexion. METHODS: Forty fresh-frozen fingers were dissected. The fingers were mounted in a custom jig, and the force required to flex the DIP joint was assessed with the PIP joint flexed 0°, 30°, 60°, and 90° and with the MCP joint flexed 0°, 45°, and 90°. The force was measured in the intact specimen, and then all measurements were repeated following sectioning of the ORL and then the central slip. RESULTS: The ORL was present on the radial and ulnar aspects of all but 2 fingers. The ORL tended to be the most robust in the ring finger. In the intact specimen, DIP flexion resistance force was maximum at 30° of PIP joint flexion and minimum at 90° of PIP joint flexion. There was a significant difference between the 90° position and all other positions of the PIP joint with respect to flexion force in the intact specimen. This meant that less force was required to flex the DIP joint at 90° of PIP joint flexion. Sectioning of the ORL revealed that it contributed 25% to the total force required to flex the DIP joint with the PIP joint at 0°, 31% at 30°, 18% at 60°, and 3% at 90° of flexion. The MCP joint position had no effect. Sectioning the central slip produced a significant increase in force required to flex the DIP joint at 90° of PIP joint flexion. CONCLUSIONS: In this study, the ORL was usually present, and it contributed up to 30% of the passive resistance to DIP joint flexion. The intact central slip accounted for the decrease in DIP joint extensor tone at 90° of PIP joint flexion. CLINICAL RELEVANCE: The ORL plays a small role in passively resisting DIP flexion.

Effect of hormone replacement and selective estrogen receptor modulators (SERMs) on the biomechanics and biochemistry of pelvic support ligaments in the cynomolgus monkey (Macaca fascicularis).

OBJECTIVE: To evaluate the effect of selective estrogen receptor modulators and ethinyl estradiol on the biomechanical and biochemical properties of the uterosacral and round ligaments in the monkey model of menopause. STUDY DESIGN: A randomized, double-blind, placebo-controlled study on 11 female macaque monkeys. Ovariectomized monkeys received 12 weeks of placebo, raloxifene, tamoxifen, or ethinyl estradiol. Biomechanical step-strain testing and real-time polymerase chain reaction was performed on the uterosacral and round ligaments. RESULTS: Tamoxifen and raloxifene uterosacrals expressed differing collagen I/III receptor density ratios, but both selective estrogen receptor modulators showed decreased tensile stiffness compared to ethinyl estradiol and controls. CONCLUSION: These findings support a possible effect of selective estrogen receptor modulators on biomechanical and biochemical properties of uterosacrals. This may play a role in pelvic organ prolapse.

Interobserver and intraobserver reliability of the Walch classification in primary glenohumeral arthritis.

INTRODUCTION: In 1999, Walch et al introduced a novel classification scheme for glenoid morphology in patients with primary glenohumeral arthritis and reported substantial intraobserver and interobserver reliability. This classification system has been widely used by shoulder surgeons but a recent independent evaluation revealed considerable lower agreement. The goal of this study was to evaluate the reproducibility of the Walch classification. MATERIAL AND METHODS: Twenty-three consecutive patients (26 shoulders) undergoing total shoulder arthroplasty (TSA) or evaluated for TSA between March 2007 and November 2007 had shoulder CT scans performed and were included in this study. Three attending shoulder surgeons and 5 shoulder/sports medicine trained fellows independently and blindly evaluated CT scans of 26 consecutive patients with primary glenohumeral arthritis, and classified each patient according to the Walch classification to determine the interobserver reliability. The intraobserver reliability was assessed by comparison of the classification of each patient by the observers on 2 occasions separated by at least 6 weeks. RESULTS: The overall interobserver agreement for all 8 observers was moderate (k=.508) for all Walch classes. The overall intraobserver reproducibility was substantial (k=.611). DISCUSSION: We have shown that the interobserver reliability of the Walch classification is moderate while the intraobserver reliability is substantial. This is similar to or superior to the reliability of many commonly used orthopaedic classification systems. While the Walch classification system is not as reliable as initially suggested and improvement of this classification system would be of utility for future clinical studies, we have shown that this is an acceptable classification system and has good clinical and research applications.

The effect of fixation technique on the stiffness of comminuted Vancouver B1 periprosthetic femur fractures.

The purpose of this study was to evaluate the stiffness of 3 different constructs for the fixation of comminuted Vancouver B1 periprosthetic femoral shaft fractures: a single lateral locking plate, a single lateral locking plate plus an anterior strut allograft, and a lateral locking plate plus an anterior locking plate. The axial stiffness, lateral bending stiffness, and torsional stiffness of 10 synthetic periprosthetic femur fracture models were tested. Differences in stiffness between constructs were determined with a 1-way repeated-measures analysis of variance. Fixation technique was found to have a significant effect for all loading modalities (P < .0001). A lateral locked plate plus an anterior locked plate was significantly stiffer than the allograft that in turn was significantly stiffer than the single plate (P < .0001).

Evaluation of glenoid capsulolabral complex insertional anatomy and restoration with single- and double-row capsulolabral repairs.

BACKGROUND: The purpose of this study was to evaluate the normal glenoid insertional anatomy of the anterior-inferior capsulolabral complex and to compare the ability of a single-row repair and a double-row suture bridge repair to restore the insertional anatomy. METHODS: Eight fresh frozen cadaver shoulders were dissected and the native glenoid insertion of the anterior-inferior capsulolabral complex was digitized. Bankart lesions were created, the shoulders were randomized to receive either the standard single-row suture anchor repair or a double-row suture bridge repair, and the insertion repair sites were then digitized. RESULTS: The single-row repair recreated 42.3% of the native footprint surface area while the double-row repair recreated 85.9%. The double-row repair was significantly larger and recreated significantly more of the native footprint compared with single-row repair (P < .01). CONCLUSION: Double-row repair of the capsulolabral complex reestablishes the native insertional footprint on the anterior inferior glenoid better than a single-row repair. LEVEL OF EVIDENCE: Basic science study.

Rotator cuff repair fluid extravasation characteristics are influenced by repair technique.

BACKGROUND: This study evaluates rotator cuff repair fluid extravasation characteristics for different rotator cuff repair techniques. METHODS: Eight fresh-frozen cadaveric shoulders were dissected free of soft tissues, with the glenohumeral joint capsule and rotator cuff muscles being left intact. A custom fluid infusion device was used to deliver fluid at constant pressure into the glenohumeral joint. The shoulders were tested in conditions of (1) intact rotator cuff, (2) supraspinatus tear, (3) repaired supraspinatus tear with a single-row technique, and (4) repaired supraspinatus tear with a double-row suture bridge technique. RESULTS: The volume per minute of saline solution extravasation for single-row repair and double-row suture bridge repair was 48.53 mL/min and 11.73 mL/min, respectively, at 2 psi; 73.3 _ 24.1 mL/min and 24.5 _ 19.7 mL/min, respectively, at 3 psi; and 95.2 _ 22.6 mL/min and 39.2 _ 23.8 mL/min, respectively, at 4 psi. There was a statistically significant greater fluid extravasation for the single-row repair compared with the double-row suture bridge repair at all 3 pressures tested (P < .05). CONCLUSION: Single-row rotator cuff repair exposes the healing zone to greater extravasation of fluid compared with double-row suture bridge repair. Therefore, double-row repair potentially enhances rotator cuff healing. LEVEL OF EVIDENCE: Controlled laboratory study.

Simulation of surgical glenoid resurfacing using three-dimensional computed tomography of the arthritic glenohumeral joint: the amount of glenoid retroversion that can be corrected.

HYPOTHESIS: The magnitude of glenoid retroversion that can be surgically corrected in total shoulder arthroplasty and still enable implantation of a glenoid component has not been established. We hypothesized that increased retroversion will require smaller glenoid components for successful implantation when the glenoid is surgically corrected and that correction beyond 20 degrees of retroversion is not feasible without peg penetration. METHODS: Using 3-dimensional models created from computed tomography of 19 patients with advanced shoulder osteoarthritis, we simulated glenoid resurfacing on varying degrees of retroverted, osteoarthritic glenoids using an in-line 3-peg glenoid component and asymmetric reaming to correct version. RESULTS: Glenoids with preoperative retroversion of less than 12 degrees could always be implanted with 46-mm and 52-mm glenoid components at neutral version without vault violation. Conversely, glenoids with greater than 18 degrees of preoperative retroversion could not be implanted at neutral version due to vault violation from the pegs. The average preoperative glenoid retroversion of patients in which a 46-mm glenoid was implanted at neutral version was 8.9 degrees +/- 6.4 degrees compared with 19.0 degrees +/- 7.1 degrees for those that could not be implanted at neutral (P = .005). DISCUSSION: Computer-aided surgical simulation shows that glenoid retroversion is a critical factor in determining successful glenoid implantation. Smaller sized glenoid components allow for greater version correction and less residual postsimulation retroversion when an in-line pegged component is used.

Comparison of Exposure in the Kaplan Versus the Kocher Approach in the Treatment of Radial Head Fractures.

BACKGROUND: The aim of this study was to compare the complete visible surface area of the radial head, neck, and coronoid in the Kaplan and Kocher approaches to the lateral elbow. The hypothesis was that the Kaplan approach would afford greater visibility due to the differential anatomy of the intermuscular planes. METHODS: Ten cadavers were dissected with the Kaplan and Kocher approaches, and the visible surface area was measured in situ using a 3-dimensional digitizer. Six measurements were taken for each approach by 2 surgeons, and the mean of these measurements were analyzed. RESULTS: The mean surface area visible with the lateral collateral ligament (LCL) preserved in the Kaplan approach was 616.6 mm2 in comparison with the surface area of 136.2 mm2 visible in the Kocher approach when the LCL was preserved. Using a 2-way analysis of variance, the difference between these 2 approaches was statistically significant. When the LCL complex was incised in the Kocher approach, the average visible surface area of the Kocher approach was 456.1 mm2 and was statistically less than the Kaplan approach. The average surface area of the coronoid visible using a proximally extended Kaplan approach was 197.8 mm2. CONCLUSIONS: The Kaplan approach affords significantly greater visible surface area of the proximal radius than the Kocher approach.