The Effect of Locking Screws on Distal Component Fixation in Total Wrist Arthroplasty Using a Cadaver Model.

Purpose: The advent of total wrist arthroplasty has allowed for motion-sparing surgical treatment for wrist arthritis. The Integra Freedom Total Wrist Arthroplasty recently incorporated locking caps into its distal component fixation to minimize implant micromotion and improve osseous integration. The purpose of this study was to assess the kinematic effect of locking caps in a cadaveric model. Methods: The Integra Freedom was implanted in 4 matched-pair cadavers and tested with and without the use of the locking caps, with the testing order randomized. Each specimen was tested on a custom testing system in a position of 15° of radial deviation, neutral position, and 15° of ulnar deviation with 25 N, 50 N, 75 N, and 100 N of compressive force. The rotation of the capitate, trapezoid, and hamate at all positions was measured using a 3-dimensional digitizer. Results: Statistical analysis showed no difference in carpal rotation between the nonlocking cap and locking cap groups at all testing loads and wrist positions. The absolute motion of the distal row was minimal. However, of the total 216 loads/positions tested, only 4 (1.8%) showed a rotation of greater than 2° and only 34 (15.7%) showed a rotation of greater than 1°. Conclusions: This study shows that in a time zero cadaveric model, the initial osseous fixation of the distal component in the Integra Freedom is robust with or without locking caps. The addition of locking caps did not have a kinematic effect on distal carpal row fixation. However, further investigation into its clinical role is necessary. Clinical Relevance: At time zero, there is minimal carpal motion after implantation of the Integra Freedom Total Wrist with functional loading. The addition of locking caps did not lead to any decrease in carpal motion.

Moderate Return to Play and Previous Performance After SLAP Repairs in Competitive Overhead Athletes: A Systematic Review.

PURPOSE: To perform a systematic review of return to play (RTP) and return to previous level of performance (RPP) in competitive overhead athletes after SLAP repair to identify factors associated with failure to RTP. METHODS: Systematic review was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Review was registered with PROSPERO International prospective register of systematic reviews (CRD42020215488). Inclusion criteria were literature reporting RTP or RPP following SLAP repair in overhead athletes were run in the following databases: PubMed/MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Google Scholar. Categories for data collection for each full article included (1) article information; (2) patient demographics; (3) surgical techniques; (4) level of competition; (5) rotator cuff treatment; (6) player position; (7) patient-reported outcome measures; and (8) RTP and RPP rates. The Methodological Index for Non-randomized Studies checklist was used to evaluate quality of all included studies. RESULTS: Eight studies with 333 subjects were identified. Overall RTP and RPP rates were 50% to 83.6% and 35.3% to 64%, respectively. Patients with surgically treated rotator cuff pathology had lower RTP (12.5%-64.7%) rates compared with those without (80.0%-83.6%). Professional athletes had similar RTP rates (62.5%-81.5%) compared with high-school (75.0%-90.0%) and college athletes (12.5%-83.3%). However, professional athletes demonstrated the lowest relative range of reported RPP rates (27.7%-55.6%). Pitchers had lower RTP (62.5%-80.0%) and RPP (52.0%-58.9%) compared with position players (91.3% RTP, 76.3%-78.2% RPP). CONCLUSIONS: Studies reviewed reported moderate RTP and RPP rates following SLAP repairs in competitive overhead athletes. Those with associated rotator cuff tear requiring treatment, and baseball pitchers were less likely to RTP and RPP. Professional athletes had similar RTP to an amateur; however, they were less likely to RPP. LEVEL OF EVIDENCE: Level IV, systematic review of Level III-IV studies.

New Approaches to the Diagnosis and Management of Periprosthetic Joint Infection of the Shoulder.

Periprosthetic joint infection (PJI) of the shoulder is a potentially devastating complication following shoulder arthroplasty. It is important to review the workup of PJI in the shoulder, including recently developed diagnostic criteria for shoulder PJI, along with detailed examination of the most common causative organism, Cutibacterium acnes. Treatment strategies for PJI of the shoulder include antibiotic therapy, surgical options, and what to do with unexpected positive cultures in revision arthroplasty. Surgeons should be familiar with bony and soft-tissue reconstructive options following explantation of an infected shoulder prosthesis.

Early clinical and radiographic outcomes of anatomic total shoulder arthroplasty with a biconvex posterior augmented glenoid for patients with posterior glenoid erosion: minimum 2-year follow-up.

BACKGROUND: Glenoid bone loss in anatomic total shoulder arthroplasty (aTSA) remains a controversial and challenging clinical problem. Previous studies have shown high rates of glenoid loosening for aTSA in shoulders with retroversion, posterior bone loss, and posterior humeral head subluxation. This study is the first to present minimum 2-year follow-up data of an all-polyethylene, biconvex augmented anatomic glenoid component for correction of glenoid retroversion and posterior humeral head subluxation. METHODS: This study is a multicenter, retrospective review of prospectively collected data on consecutive patients from 7 global clinical sites. All patients underwent aTSA using the biconvex posterior augmented glenoid (PAG). Inclusion criteria were preoperative computed tomographic (CT) scan, minimum 2 years since surgery, preoperative and minimum 2-year postoperative range of motion examination, and patient-reported outcome measures (PROMs). Glenoid classification, glenoid retroversion, and posterior humeral head subluxation were measured from preoperative CT and radiography and postoperative radiography. Statistical comparisons between pre- and postoperative values were performed with a paired t test. RESULTS: Eighty-six of 110 consecutive patients during the study period (78% follow-up) met the inclusion criteria and were included in our analysis. Mean follow-up was 35 ± 10 months, with a mean age of 68 ± 8 years (range 48-85). Range of motion statistically improved in all planes from pre- to postoperation. Mean visual analog scale score improved from 5.2 preoperation to 0.7 postoperation, Single Assessment Numeric Evaluation score from 43.2 to 89.5, Constant score from 41.8 to 76.9, and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score from 49.8 to 86.7 (all P < .0001). Mean glenoid retroversion improved from 19.3° to 7.4° (P < .0001). Posterior subluxation improved from 69.1% to 53.5% and posterior decentering improved from 5.8% to -3.0% (P < .0001). There was 1 patient with both a prosthetic joint infection and radiographic glenoid loosening that required revision. Seventy-nine of 86 patients had a Lazarus score of 0 (no radiolucency seen about peg or keel) at final follow-up. CONCLUSIONS: This study shows that at minimum 2-year follow-up, a posterior-augmented all-polyethylene glenoid can correct glenoid retroversion and posterior humeral head subluxation. Clinically, there was significant improvement in both range of motion and PROMs.

Anatomic Posterolateral Corner Reconstruction Using a Fibula Cross-Tunnel Technique: A Cadaveric Biomechanical Study.

PURPOSE: To compare the biomechanical properties of a fibula cross-tunnel technique for posterolateral corner (PLC) reconstruction with those of intact knees. METHODS: Seven fresh-frozen cadaveric knees were tested while intact, after PLC tear, and after reconstruction. Testing of the parameters listed above was performed at 0°, 30°, 60°, and 90° of knee flexion. Reconstruction was performed using 2 independent tendon autografts. Afterward, the fibula and graft were loaded to failure. RESULTS: Reconstruction restored external rotation (0°: 11.75° ± 2.02° to 9.81° ± 1.81°, P = .57; 30°: 17.91° ± 1.32° to 13.96° ± 2.84°, P = .12; 60°: 15.86° ± 1.68° to 13.26° ± 3.58°, P = .41; 90°: 15.53° ± 1.62° to 14.07° ± 2.95°, P = .54) to the intact state, and posterior translation (0°: 3.66 ± 0.85 mm to 3.31 ± 0.89 mm, P = .87; 60°: 3.15 ± 0.45 mm to 2.96 ± 0.45 mm, P = .73; 90°: 2.74 ± 0.33 mm to 3.05 ± 0.41 mm, P = .41) and varus angulation (0°: 0.92° ± 0.35° to 1.98° ± 0.42°, P = .55; 30°: 2.65° ± 0.27° to 1.09° ± 0.90°, P = .37; 90°: 4.29° ± 0.44° to 2.53° ± 1.13°, P = .19) under most conditions. During load to failure testing, the construct revealed properties similar to those of native structures (yield load: 330.4 ± 45.8 N; ultimate load: 420.9 ± 37.4 N). CONCLUSIONS: This technique restored external rotation to the intact state after PLC injury in all testing conditions, as well as posterior translation at 0°, 60°, and 90° of flexion, and varus angulation under all conditions tested except 60° of flexion. CLINICAL RELEVANCE: Clinically, this surgical technique may eliminate the need for a tibial tunnel for posterolateral corner reconstruction.

The effects of prosthetic humeral head shape on glenohumeral joint kinematics during humeral axial rotation in total shoulder arthroplasty.

BACKGROUND: A non-spherical humeral head has been shown to influence kinematics and stability of the glenohumeral joint; yet, most prosthetic humeral head components are designed to be a perfect sphere. The effect of humeral head shape on prosthetic joint kinematics after total shoulder arthroplasty is not well understood. We hypothesized that prosthetic joint kinematics during humeral axial rotation is dependent on humeral head shape, regardless of joint conformity. METHODS: Four prosthetic configurations were investigated using a spherical and a non-spherical prosthetic humeral head articulated with a conforming and a non-conforming glenoid component. Testing was performed in the coronal, scapular, and forward flexion plane at 0°, 30°, and 60° of abduction. Prosthetic joint kinematics was measured in 10° intervals during a 100° arc of humeral axial rotation. Glenohumeral translation patterns, net glenohumeral translation, and averaged glenohumeral translation were compared for each of 4 configurations. RESULTS: Non-spherical head configurations increased the net glenohumeral translation during humeral axial rotation in multiple test positions compared with spherical head configurations (P < .05). Spherical head configurations resulted in a relatively small amount of glenohumeral translation, less than 2 mm. The radius of curvature of the glenoid component alone did not affect the net glenohumeral translation within each of the 2 head groups (P > .05). CONCLUSION: During humeral axial rotation, the non-spherical humeral head shape contributes to increased glenohumeral translation during humeral axial rotation. However, the spherical head shape does not show significant glenohumeral translation during humeral axial rotation, regardless of glenoid conformity.

The effect of long and short head biceps loading on glenohumeral joint rotational range of motion and humeral head position.

PURPOSE: To evaluate the effect of loading the long and short heads of the biceps on glenohumeral range of motion and humeral head position. METHODS: Eight cadaveric shoulders were tested in 60° abduction in the scapula and coronal plane. Muscle loading was applied based on cross-sectional area ratios. The short and long head of the biceps were loaded individually followed by combined loading. Range of motion was measured with 2.2 Nm torque, and the humeral head apex position was measured using a MicroScribe. A paired t test with Bonferroni correction was used for statistics. RESULTS: Long head loading decreased internal rotation in both the scapular (17.9 %) and coronal planes (5.7 %) and external rotation in the scapular plane (2.6 %) (P < 0.04). With only short head loading, maximum internal rotation was significantly increased in the scapular and coronal plane. Long head and short head loading shifted the humeral head apex posteriorly in maximum internal rotation in both planes with the long head shift being significantly greater than the short head. Long head loading also shifted the humeral apex inferiorly in internal rotation and inferiorly posteriorly in neutral rotation in the scapular plane. With the long head unloaded, there was a significant superior shift with short head loading in both planes. CONCLUSION: Loading the long head of the biceps had a much greater effect on glenohumeral range of motion and humeral head shift than the short head of the biceps; however, in the absence of long head loading, with the short head loaded, maximum internal rotation increases and the humeral head shifts superiorly, which may contribute to impingement following tenodesis of the long head of the biceps. These small changes in rotational range of motion and humeral head position with biceps tenodesis may not lead to pathologic conditions in low-demand patients; however, in throwers, biceps tenodesis may lead to increased contact pressures in late-cocking and deceleration that will likely translate to decreased performance therefore every effort should be made to preserve the biceps-labral complex.

Biomechanical comparison of single-row, double-row, and transosseous-equivalent repair techniques after healing in an animal rotator cuff tear model.

The transosseous-equivalent (TOE) rotator cuff repair technique increases failure loads and contact pressure and area between tendon and bone compared to single-row (SR) and double-row (DR) repairs, but no study has investigated if this translates into improved healing in vivo. We hypothesized that a TOE repair in a rabbit chronic rotator cuff tear model would demonstrate a better biomechanical profile than SR and DR repairs after 12 weeks of healing. A two-stage surgical procedure was performed on 21 New Zealand White Rabbits. The right subscapularis tendon was transected and allowed to retract for 6 weeks to simulate a chronic tear. Repair was done with the SR, DR, or TOE technique and allowed to heal for 12 weeks. Cyclic loading and load to failure biomechanical testing was then performed. The TOE repair showed greater biomechanical characteristics than DR, which in turn were greater than SR. These included yield load (p < 0.05), energy absorbed to yield (p < 0.05), and ultimate load (p < 0.05). For repair of a chronic, retracted rotator cuff tear, the TOE technique was the strongest biomechanical construct after healing followed by DR with SR being the weakest.

Radioscapholunate arthrodesis with excision of the distal scaphoid: comparison of contact characteristics to the intact wrist.

PURPOSE: To evaluate the midcarpal contact characteristics at the lunocapitate (LC) and scaphotrapezio-trapezoidal (STT) joints in 3 wrist conditions: intact, after simulating a radioscapholunate (RSL) arthrodesis, and after an RSL arthrodesis with distal scaphoid excision (DSE). METHODS: Eight fresh-frozen cadaveric specimens were tested using a custom jig with the wrist in neutral, 15° and 30° flexion and extension, 10° radial deviation, and 20° ulnar deviation. The RSL arthrodesis was performed using 2.4-mm distal radius plates with locking screws. Using a pressure sensor, contact force, average pressure, peak pressure, and contact area at the STT and LC joints were measured for 3 conditions: intact wrist, RSL arthrodesis, and RSL arthrodesis with DSE. RESULTS: Following RSL arthrodesis, average and peak pressure at the LC joint increased significantly compared to the intact wrist. In the STT joint, the average and peak contact pressure increased significantly compared to the intact wrist. Following DSE, average and peak pressure at the LC joint increased further compared to the RSL arthrodesis condition. CONCLUSIONS: Our findings showed increased contact pressures in the STT and LC joint following RSL arthrodesis, which may explain the clinical findings of midcarpal arthritis. Also, although DSE may improve short-term range of motion and clinical incidence of midcarpal arthritis, our findings showed that this comes at a cost, as the remaining portions of the midcarpal joint are subject to higher forces and pressures following DSE. CLINICAL RELEVANCE: Radioscapholunate arthrodesis results in increased midcarpal contact pressures that may explain the clinical incidence of midcarpal arthritis. Excision of the distal scaphoid further increases contact pressures in the remaining midcarpal joint and may further increase the incidence of midcarpal arthritis. These alterations in contact characteristics of the midcarpal joint should be considered when excising the distal scaphoid for improved range of motion.

The effects of prosthetic humeral head shape on glenohumeral joint kinematics: a comparison of non-spherical and spherical prosthetic heads to the native humeral head.

BACKGROUND: The purpose of this study was to quantitatively evaluate the effect of the prosthetic humeral head shape on rotational range of motion and glenohumeral joint kinematics. METHODS: Six fresh-frozen cadaveric shoulders were tested in multiple positions under anatomic muscle loading. Specimens were tested for the native head, and then the spherical and non-spherical prosthetic heads were randomly implanted in the same stem to preserve the center of rotation. Rotational range of motion was measured with 3.3 Nm of torque. Glenohumeral joint kinematics was quantified by the position vectors of the humeral head apex (HHA) and geometric center of the humeral head (GCHH) to calculate translation of HHA and GCHH per degree of humeral rotation. RESULTS: The non-spherical prosthetic head replicated the native head shape more accurately than the spherical prosthetic head. Between the non-spherical and native heads, there was no statistical difference in rotational range of motion (P > .05), but a statistical difference in HHA and GCHH translation was found at 60° of scapular plane abduction in the interval from 30° of internal rotation to neutral rotation and at 30° of forward flexion plane abduction in the interval from 30° of external rotation to maximum external rotation, respectively (P < .05). The spherical head significantly decreased rotational range of motion (P < .05), increased HHA translation per degree (P < .05), and decreased GCHH translation per degree (P < .05) in multiple positions compared with the native humeral head. CONCLUSION: The custom, non-spherical prosthetic head more accurately replicated the head shape, rotational range of motion, and glenohumeral joint kinematics than the commercially available, spherical prosthetic head compared with the native humeral head.

Margin convergence anchorage to bone for reconstruction of the anterior attachment of the rotator cable.

PURPOSE: The purpose of this study was to compare the biomechanical characteristics of a massive L-shaped retracted rotator cuff tear repaired with either soft-tissue side-to-side sutures or margin convergence anchorage to bone. METHODS: Eight matched pairs of cadaveric shoulders were used. The supraspinatus and infraspinatus were secured in a clamp at 30° of glenohumeral abduction. The subscapularis was secured in a separate clamp, and a constant load was applied. A massive L-shaped rotator cuff tear of the supraspinatus and infraspinatus tendon was created. In all specimens the posterior aspect of the tear was repaired by a transosseous-equivalent technique. In 1 group we placed 2 margin convergence sutures between the supraspinatus and the rotator interval. In the comparison group, a suture anchor was inserted at the anterior attachment of the rotator cable. Margin convergence anchorage to bone was then performed between the supraspinatus and the rotator interval. Each specimen was tested with an Instron machine (Instron, Canton, MA) and a video digitizing system. A paired t test was used for statistical analysis. RESULTS: Margin convergence anchorage to bone decreased gap formation at cycle 1, cycle 30, and yield load across the entire footprint (P < .05). In both constructs the anterior gap was greater than the posterior gap at cycle 1, cycle 30, and yield load (P < .05). Margin convergence anchorage to bone decreased hysteresis and increased stiffness during the first cycle and increased yield load (P < .05). CONCLUSIONS: Using margin convergence anchorage to bone to restore the anterior attachment of the rotator cable decreased gap formation across the entire footprint and improved biomechanical properties for cycle 1 and yield load compared with soft-tissue margin convergence for massive rotator cuff repairs. CLINICAL RELEVANCE: Repairing the anterior rotator cuff with margin convergence anchorage to bone may improve clinical outcomes of an L-shaped massive tear repair.