Effect of Commercially Available Wound Irrigation Solutions on Uninfected Host Tissue in a Murine Model.

Background: Commercially available irrigation solutions are used to reduce bacterial contamination and prevent surgical site infections. However, the effect of these solutions on the healing capacity of tissue has not been well-established. The purpose of this study was to investigate the effects of 5 commercially available irrigation solutions on host tissue in a murine model. Methods: There were 5 treatment groups: bacitracin, Clorpactin, Irrisept, Prontosan, Bactisure, and normal saline control. The irrigation solutions were applied to the wound for 30 seconds or 1 minute, as per the manufacturer's instructions, and then washed with normal saline. Mice were sacrificed at 3 days and 10 days. The tissue was examined histologically for inflammation, edema, granulation tissue formation, and re-epithelialization. Granulation tissue formation and re-epithelialization were surrogates for effective wound healing. Results: All of the irrigation solutions had negative effects on host tissue in the acute phase. The inflammation and edema were improved in the later phase (10 days). Recovery and healing of the open wounds were observed for all groups at 10 days. The antiseptic irrigation solutions had similar cytotoxic effects on host tissue at 3 days and did not have delayed or compromised wound healing at 10 days when compared to normal saline control. Conclusions: Single short-duration use of these commercially available antiseptic irrigation solutions appears to be safe in an uninfected wound. Data from this study will provide surgeons with useful information regarding the safety of using antiseptic wound irrigation solutions intraoperatively for prevention of surgical site infections.

Accuracy of Leg Length and Hip Offset Measurements Using a Fluoroscopic Grid During Anterior Approach Total Hip Arthroplasty.

Background: Minimizing leg length (LLD) and hip offset (OD) discrepancies is critical for tissue tension and implant longevity in total hip arthroplasty (THA). The direct anterior approach (DAA) helps surgeons recreate these values under fluoroscopy. Several methods to accomplish this have been described, with no consensus on which is superior. This study evaluated the ability to minimize LLD and OD using a surgeon-controlled, adjustable fluoroscopic grid. We hypothesized that this tool would recreate parameters to within 10 mm of the contralateral side. Methods: One hundred eleven primary THAs performed with an adjustable radiopaque grid to equalize leg length and hip offset were retrospectively reviewed. These values were measured on postoperative radiographs and compared to the contralateral hip. Patients were excluded if they had inadequate imaging, revision arthroplasty, preexisting deformities, or underwent approaches other than DAA. Results: Mean age was 59.1 ± 11.1 years, 63.1% of patients were female, and average body mass index was 27.8 ± 7.0. Mean LLD was 3.7 ± 3.0 mm, while mean OD was 4.6 ± 3.6 mm. 95.5% of hips showed LLD < 10 mm, while 93.7% of hips had OD < 10 mm. Furthermore, 76.6% of hips had LLD < 5 mm, while 62.2% of hips had OD < 5 mm. Conclusions: The described technique restored limb length and hip offset during DAA THA. This technique yields consistent results and offers an inexpensive alternative to costly digital software and more cumbersome fixed grid systems.

Early Survivorship of Uncemented Total Knee Arthroplasty Varies by Age and Sex Based on Data From the Michigan Arthroplasty Registry Collaborative Quality Initiative.

BACKGROUND: Outcome data for newer uncemented total knee arthroplasty (TKA) designs has been mixed. Registry studies showed worse survivorship, but clinical trials have not demonstrated differences compared to cemented designs. There has been renewed interest in uncemented TKA with modern designs and improved technology. The utilizations of uncemented knees in Michigan, 2-year outcomes, and the effects of age and sex were evaluated. METHODS: A statewide database from 2017 through 2019 was analyzed for incidence, distribution, and early survivorship of cemented versus uncemented TKAs. There was 2-year minimum follow-up. Kaplan-Meier survival analysis was used to generate time to first revision cumulative percent revision curves. The impacts of age and sex were examined. RESULTS: Use of uncemented TKAs increased from 7.0 to 11.3%. Uncemented TKAs were more commonly men, younger, heavier, American Society of Anesthesiologists score > 2, and opioid users (P < .05). At 2 years, overall cumulative percent revision was higher in uncemented (2.44% [2.00, 2.99]) versus cemented (1.76% [1.64, 1.89]), particularly in women uncemented (2.41 [1.87, 3.12]) versus cemented (1.64 [1.50, 1.80]). Revision rates were greater with uncemented women >70 years (1.2% 1 year, 1.02% 2 years) versus < 70 years (0.56%, 0.53%), notably uncemented were inferior in both groups (P < .05). Men, regardless of age, had similar survivorships with both cemented and uncemented designs. CONCLUSION: The use of an uncemented TKA had an increased risk of early revision compared to cemented. This finding, however, was only apparent in women, especially those >70 years old. Surgeons should consider cement fixation in women >70 years.

Effect of Slope and Varus Correction High Tibial Osteotomy in the ACL-Deficient and ACL-Reconstructed Knee on Kinematics and ACL Graft Force: A Biomechanical Analysis.

BACKGROUND: Correction of high posterior tibial slope is an important treatment option for revision of anterior cruciate ligament (ACL) failure as seen in clinical and biomechanical studies. In cases with moderate to severe medial compartment arthritis, an additional varus correction osteotomy may be added to improve alignment. PURPOSE: To investigate the influence of coronal and sagittal correction high tibial osteotomy in ACL-deficient and ACL-reconstructed knees on knee kinematics and ACL graft load. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric knees were selected according to previous computed tomography measurements with increased native slope and slight varus tibial alignment (mean ± SD): slope, 9.9°± 1.4°; medial proximal tibia angle, 86.5°± 2.1°; age, 47.7 ± 5.8 years. A 10° anterior closing-wedge osteotomy, as well as an additional 5° of simulated varus correction osteotomy, were created and fixed using an external fixator. Four alignment conditions-native, varus correction, slope correction, and combined varus and slope correction-were randomly tested in 2 states: ACL-deficient and ACL-reconstructed. Compressive axial loads were applied to the tibia while mounted on a free-moving X-Y table and free-rotating tibia in a knee testing fixture. Three-dimensional motion tracking captured anterior tibial translation (ATT) and internal tibial rotation. Change of tensile forces on the reconstructed ACL graft were recorded. RESULTS: In the ACL-deficient knee, an isolated varus correction led to a significant increase of ATT by 4.3 ± 4.0 mm (P = .04). Isolated slope reduction resulted in the greatest decrease of ATT by 6.2 ± 4.3 mm (P < .001). In the ACL-reconstructed knee, ATT showed comparable changes, while combined varus and slope correction led to lower ATT by 3.7 ± 2.6 mm (P = .01) than ATT in the native alignment. Internal tibial rotation was not significantly altered by varus correction but significantly increased after isolated slope correction by 4.0°± 4.1° (P < .01). Each isolated or combined osteotomy showed decreased forces on the graft as compared with the native state. The combined varus and slope osteotomy led to a mean decrease of ACL graft force by 33% at 200 N and by 58% at 400 N as compared with the native condition (P < .001). CONCLUSION: A combined varus and slope correction led to a relevant decrease of ATT in the ACL-deficient and ACL-reconstructed cadaveric knee. ACL graft forces were significantly decreased after combined varus and slope correction. Thus, our biomechanical findings support the treatment goal of a perpendicular-aligned tibial plateau for ACL insufficiencies, especially in cases of revision surgery. CLINICAL RELEVANCE: This study shows the beneficial knee kinematics and reduced forces on the ACL graft after combined varus and slope correction.

The Effect of Glenohumeral Fixation Angle on Deltoid Function During Superior Capsule Reconstruction: A Biomechanical Investigation.

PURPOSE: To evaluate the effect of dermal allograft fixation at different angles of glenohumeral abduction on deltoid forces during superior capsule reconstruction (SCR). METHODS: Fifteen cadaveric specimens were tested using a dynamic shoulder simulator. Following testing in the native state, shoulders underwent SCR in 2 of 5 possible fixation angles; 0°, 15°, 30°, 45°, or 60° of glenohumeral abduction, allowing for 6 specimens per group. Angles were measured radiographically with the glenoid fixed perpendicular to the floor. Maximum mean deltoid abduction force was compared among 5 separate conditions within each angle group: (1) native shoulder, (2) complete supraspinatus (SSP) and superior capsule tear, (3) SCR alone, (4) SCR with posterior margin sutured, and (5) SCR with anterior and posterior margins sutured. RESULTS: SSP tears significantly increased the maximum deltoid forces for all 5 fixation angles compared with the native state (P < .05). Specimens repaired at 0°, 30°, and 45° were unable to restore deltoid forces compared with the native state in any condition (P < .05). SCR at 15° with anterior and posterior margin convergence showed similar abduction forces compared with the native state (P = .19). When fixed at 60° abduction, SCR alone significantly reduced deltoid forces compared to SSP (Δ143N, P < .001) and native (Δ48N, P < .001). No significant differences were found between the 3 repair subtypes (SCR ± anterior/posterior margin repair) in the 60° group. CONCLUSIONS: SCR with anterior and posterior margin convergence tensioned at 15° of glenohumeral abduction showed similar deltoid abduction force requirements compared with the native state, whereas graft fixation in 60° significantly reduced deltoid force in all SCR conditions. CLINICAL RELEVANCE: Increased graft tension with a greater abduction angle may provide greater functional outcome by placing less load on the deltoid. In contrast, graft fixation in lower abduction angles may require additional margin convergence to reproduce native forces.

Repair of the medial patellofemoral ligament with suture tape augmentation leads to similar primary contact pressures and joint kinematics like reconstruction with a tendon graft: a biomechanical comparison.

PURPOSE: To compare suture tape-augmented MPFL repair with allograft MPFL reconstruction using patellofemoral contact pressure and joint kinematics to assess the risk of patellofemoral over-constrainment at point zero. METHODS: A total of ten fresh frozen cadaveric knee specimens were tested in four different conditions of the MPFL: (1) native, (2) cut, (3) reconstructed with tendon graft, and (4) augmented with suture tape. The patellofemoral mean pressure (MP), peak pressure (PP) and contact area (CA) were measured independently for the medial and lateral compartments using pressure-sensitive films. Patellar tilt (PT) and shift (PS) were measured using an optical 3D motion tracking system. Measurements were recorded at 0°, 10°, 20°, 30°, 60° and 90° of flexion. Both the tendon graft and the internal brace were preloaded with 2 N, 5 N, and 10 N. RESULTS: There was no significant differences found between surgical methods for medial MP, medial PP, medial CA, lateral MP and PS at any preload or flexion angle. Significant differences were seen for lateral PP at 20° knee flexion and 10 N preload (suture tape vs. reconstruction: 1045.9 ± 168.7 kPa vs. 1003.0 ± 151.9 kPa; p = 0.016), for lateral CA at 10° knee flexion and 10 N preload (101.4 ± 39.5 mm2 vs. 108.7 ± 36.6 mm2; p = 0.040), for PT at 10° knee flexion and 2 N preload (- 1.9 ± 2.5° vs. - 2.5 ± 2.3°; p = 0.033) and for PT at 0° knee flexion and 10 N preload (- 0.8 ± 2.5° vs. - 1.8 ± 3.1°; p = 0.040). A preload of 2 N on the suture tape was the closest in restoring the native joint kinematics. CONCLUSIONS: Suture tape augmentation of the MPFL resulted in similar primary contact pressures and joint kinematics in comparison with MPFL reconstruction using a tendon graft. A pretension of 2 N was found to restore the knee joint closest to normal patellofemoral kinematics.

Acellular dermal matrix augmentation significantly increases ultimate load to failure of pectoralis major tendon repair: a biomechanical study.

BACKGROUND: Biomechanical studies have demonstrated that standard pectoralis major tendon (PMT) repairs have inferior strength compared with native tendon. HYPOTHESIS: Augmentation of PMT repair with an acellular dermal matrix (ADM) will increase the ultimate load to failure. METHODS: Eighteen cadaveric specimens were allocated to 3 repair groups: standard repair (SR); augmented repair (AR) with ADM; and intact, native tendon (NT). Specimens were tested for cyclic elongation, linear stiffness, load to 5 mm displacement, maximum load to failure, and method of failure. RESULTS: Maximum load to failure in AR (1450 ± 295 N) was significantly higher than SR (921 ± 159 N; P = .0042) and equivalent to NT (1289 ± 240 N; P = .49). NT required the highest load to displace 5 mm (709 ± 202 N), which was higher than AR (346 ± 95 N; P < .001) and SR (375 ± 55; P = .0015). NT stiffness (125 ± 42 N/mm) was greater than the AR (69 ± 19 N/mm; P = .0073) or SR (75 ± 11 N/mm; P = .015). The mode of failure for SR was suture pullout from the PMT as opposed to button pullout from the humerus (fracture) for AR. CONCLUSION: ADM augmentation of PMT repair significantly increases ultimate load to failure.

Slope-reducing tibial osteotomy decreases ACL-graft forces and anterior tibial translation under axial load.

PURPOSE: Posterior tibial slope (PTS) represents an important risk factor for anterior cruciate ligament (ACL) graft failure, as seen in clinical studies. An anterior closing wedge osteotomy for slope reduction was performed to investigate the effect on ACL-graft forces and femoro-tibial kinematics in an ACL-deficient and ACL-reconstructed knee in a biomechanical setup. METHODS: Ten cadaveric knees with a relatively high native slope (mean ± SD): (slope 10° ± 1.4°, age 48.2 years ± 5.8) were selected based on prior CT measurements. A 10° anterior closing-wedge osteotomy was fixed with an external fixator in the ACL-deficient and ACL-reconstructed knee (quadruple Semi-T/Gracilis-allograft). Each condition was randomly tested with both the native tibial slope and the post-osteotomy reduced slope. Axial loads (200 N, 400 N), anterior tibial draw (134 N), and combined loads were applied to the tibia while mounted on a free moving and rotating X-Y table. Throughout testing, 3D motion tracking captured anterior tibial translation (ATT) and internal tibial rotation (ITR). Change of forces on the reconstructed ACL-graft (via an attached load-cell) were recorded, as well. RESULTS: ATT was significantly decreased after slope reduction in the ACL-deficient knee by 4.3 mm ± 3.6 (p < 0.001) at 200 N and 6.2 mm ± 4.3 (p < 0.001) at 400N of axial load. An increase of ITR of 2.3° ±2.8 (p < 0.001) at 200 N and by 4.0° ±4.1 (p < 0.001) at 400 N was observed after the osteotomy. In the ACL-reconstructed knee, ACL-graft forces decreased after slope reduction osteotomy by a mean of 14.7 N ± 9.8 (p < 0.001) at 200 N and 33.8 N ± 16.3 (p < 0.001) at 400N axial load, which equaled a relative decrease by a mean of 17.0% (SD ± 9.8%), and 33.1% (SD ± 18.1%), respectively. ATT and ITR were not significantly changed in the ACL-reconstructed knee. Testing of a tibial anterior drawing force in the ACL-deficient knee led to a significantly increased ATT by 2.7 mm ± 3.6 (p < 0.001) after the osteotomy. The ACL-reconstructed knee did not show a significant change (n.s.) in ATT after the osteotomy. However, ACL-graft forces detected a significant increase by 13.0 N ± 8.3 (p < 0.001) after the osteotomy with a tibial anterior drawer force, whereas the additional axial loading reduced this difference due to the osteotomy (5.3 N ± 12.6 (n.s.)). CONCLUSIONS: Slope-reducing osteotomy decreased anterior tibial translation in the ACL-deficient and ACL-reconstructed knee under axial load, while internal rotation of the tibia increased in the ACL-deficient status after osteotomy. Especially in ACL revision surgery, the osteotomy protects the reconstructed ACL with significantly lower forces on the graft under axial load.

Relationship Between Deltoid and Rotator Cuff Muscles During Dynamic Shoulder Abduction: A Biomechanical Study of Rotator Cuff Tear Progression.

BACKGROUND: Previous biomechanical studies regarding deltoid function during glenohumeral abduction have primarily used static testing protocols. HYPOTHESES: (1) Deltoid forces required for scapular plane abduction increase as simulated rotator cuff tears become larger, and (2) maximal abduction decreases despite increased deltoid forces. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen cadaveric shoulders with a mean age of 67 years (range, 64-74 years) were used. The supraspinatus and anterior, middle, and posterior deltoid tendons were attached to individual shoulder simulator actuators. Deltoid forces and maximum abduction were recorded for the following tear patterns: intact, isolated subscapularis (SSC), isolated supraspinatus (SSP), anterosuperior (SSP + SSC), posterosuperior (infraspinatus [ISP] + SSP), and massive (SSC + SSP + ISP). Optical triads tracked 3-dimensional motion during dynamic testing. Fluoroscopy and computed tomography were used to measure critical shoulder angle, acromial index, and superior humeral head migration with massive tears. Mean values for maximum glenohumeral abduction and deltoid forces were determined. Linear mixed-effects regression examined changes in motion and forces over time. Pearson product-moment correlation coefficients ( r) among deltoid forces, critical shoulder angles, and acromial indices were calculated. RESULTS: Shoulders with an intact cuff required 193.8 N (95% CI, 125.5 to 262.1) total deltoid force to achieve 79.8° (95% CI, 66.4° to 93.2°) of maximum glenohumeral abduction. Compared with native shoulders, abduction decreased after simulated SSP (-27.2%; 95% CI, -43.3% to -11.1%, P = .04), anterosuperior (-51.5%; 95% CI, -70.2% to -32.8%, P < .01), and massive (-48.4%; 95% CI, -65.2% to -31.5%, P < .01) cuff tears. Increased total deltoid forces were required for simulated anterosuperior (+108.1%; 95% CI, 68.7% to 147.5%, P < .01) and massive (+57.2%; 95% CI, 19.6% to 94.7%, P = .05) cuff tears. Anterior deltoid forces were significantly greater in anterosuperior ( P < .01) and massive ( P = .03) tears. Middle deltoid forces were greater with anterosuperior tears ( P = .03). Posterior deltoid forces were greater with anterosuperior ( P = .02) and posterosuperior ( P = .04) tears. Anterior deltoid force was negatively correlated ( r = -0.89, P = .01) with critical shoulder angle (34.3°; 95% CI, 32.0° to 36.6°). Deltoid forces had no statistical correlation with acromial index (0.55; 95% CI, 0.48 to 0.61). Superior migration was 8.3 mm (95% CI, 5.5 to 11.1 mm) during testing of massive rotator cuff tears. CONCLUSION: Shoulders with rotator cuff tears require considerable compensatory deltoid function to prevent abduction motion loss. Anterosuperior tears resulted in the largest motion loss despite the greatest increase in deltoid force. CLINICAL RELEVANCE: Rotator cuff tears place more strain on the deltoid to prevent abduction motion loss. Fatigue or injury to the deltoid may result in a precipitous decline in abduction, regardless of tear size.

The Integrity of the Acromioclavicular Capsule Ensures Physiological Centering of the Acromioclavicular Joint Under Rotational Loading.

BACKGROUND: The acromioclavicular (AC) capsule is an important stabilizer against horizontal translation and also contributes to the strut function of the clavicle, which guides rotation of the scapula. To best reproduce the biomechanical properties and the complex 3-dimensional (3D) guidance of the AC joint, detailed knowledge of the contribution of each of the distinctive capsular structures is needed. Purpose/Hypothesis: To perform a detailed biomechanical evaluation of the specific capsular structures of the AC joint and their contribution to translational and rotational stability. The hypothesis was that successive cutting of each quadrant of the AC capsule would result in increased instability and increased amplitude of the clavicle's motion in relation to the acromion. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-two fresh-frozen human cadaveric shoulders were used. Each scapula was fixed to a swivel fixture of a servohydraulic materials testing system. The AC capsule was dissected in serial steps with immediate rotational and horizontal testing after each cut. A 3D optical measuring system was used to evaluate 3D movement. Posterior translation, rotation, and displacement of the lateral clavicle in relation to the center of rotation were measured. Torques and axial forces required to rotate and translate the clavicle were recorded. RESULTS: When posterior translational force was applied, all specimens with a completely cut AC capsule demonstrated a significant loss of resistance force against the translational motion when compared with the native state ( P < .05). The resistance force against posterior translation was reduced to less than 27% of the native state for all specimens. Sequential cutting of the AC capsule resulted in a significant reduction of resistance torque against anterior rotation for all specimens with less than 22% of resistance force compared with the native state. Cutting 50% of the capsule reduced the resistance torque for all segments and all testing modalities (posterior translation as well as anterior and posterior rotation) significantly compared with the native state ( P < .05). Cutting the entire AC capsule resulted in a significant increase in motion within the joint as a sign of decentering of the AC joint when torque was applied. All groups demonstrated a significant increase of motion in all directions when the AC capsule was cut by 50%. CONCLUSION: Cutting the entire capsule (with intact coracoclavicular [CC] ligaments) reduced the resistance force to less than 25% compared with the native state during translational testing and less than 10% compared with the native state during rotational testing. However, the anterior segments of the capsule provided the greatest stability under rotational loading. Second, the amplitude of the joint's motion significantly increased under rotational stress, indicating increased amplitude of the clavicle's motion in relation to the acromion when the ligamentous structures of the AC capsule are dissected. CLINICAL RELEVANCE: To best restore stability to the AC joint, the relevance and function of each section of the circumferential AC capsule need to be understood. Our findings support the synergistic contribution of the CC ligaments and AC capsular structures to AC joint stability. This synergy supports the need to address both structures to achieve anatomic reconstruction.

Pectoralis Major Repair: A Biomechanical Analysis of Modern Repair Configurations Versus Traditional Repair Configuration.

BACKGROUND: Pectoralis major (PM) ruptures are increasingly common, and a variety of surgical techniques have been described. However, tested techniques have demonstrated diminished strength with inadequate restoration of the footprint and suture failure at relatively low loads. Purpose/Hypothesis: The purpose was to biomechanically compare PM transosseous suture repair (current gold standard) to modern PM repair techniques that use larger caliber sutures, suture tape, and unicortical button fixation (UBF). The null hypothesis was that there would be no mechanical difference between repair techniques and no difference in the amount of footprint restoration. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty-four fresh-frozen cadaveric shoulders controlled for age and bone mineral density were randomized equally to 4 groups: (1) UBF, suture tape; (2) UBF, No. 5 suture, suture tape; (3) bone trough with No. 2 suture; and (4) native PM tendon group; all groups were tested to failure. The specimens were tested under cycling loads (10 N to 125 N) with a final load-to-failure test at 1 mm/s. Failure modes were classified by location and cause of rupture based on optical markers, while tendon footprint length was measured to determine amount of footprint restoration. RESULTS: For fixation strength, the mean peak load was significantly greater in the native tendon (1816 ± 706 N) versus UBF/No. 5 suture/suture tape (794 ± 168 N), UBF/suture tape (502 ± 201 N), and bone trough (492 ± 151 N) ( P < .001 for all). UBF/No. 5 suture/suture tape featured the lowest displacement superiorly (1.09 ± 0.47 mm) and inferiorly (1.14 ± 0.39 mm) with a significant difference compared with bone trough. With regard to tendon footprint reapproximation, cortical button fixation best approximated native tendon footprint length versus bone trough. CONCLUSION: Based on peak failure load, the UBF/No. 5 suture/suture tape construct demonstrated 61% greater construct strength than a traditional bone trough technique. Moreover, displacement after cyclic loading was by far smallest in the UBF/No. 5 suture/suture tape construct. Therefore, repair constructs with larger caliber suture and suture tape provide a measurable improvement in construct strength versus traditional PM repair techniques in a biomechanical model and may be advantageous for repair. CLINICAL RELEVANCE: Cortical button fixation with larger caliber suture and suture tape allows for a significantly better PM repair than more traditional techniques at the time of surgery, which may ultimately result in improved clinical outcomes if implemented in surgical practice.