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Background: The bone–patellar tendon–bone (BTB) autograft is associated with difficulty with kneeling after anterior cruciate ligament (ACL) reconstruction; however, it is unclear whether it results in a more painful or symptomatic knee compared with the hamstring tendon autograft. Purpose: To identify the rate and risk factors for knee pain and difficulty with kneeling after ACL reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: Primary ACL reconstruction procedures prospectively recorded in the New Zealand ACL Registry from April 2014 to May 2021 were analyzed. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used to identify patients reporting consequential knee pain (CKP), defined as a KOOS Pain subscore of ≤72 points, and severe kneeling difficulty (SKD), defined as a self-report of "severe" or "extreme" difficulty with kneeling. Absolute values of the KOOS Pain and Symptoms subscales were also compared. Results: A total of 10,999 patients were analyzed. At 2-year follow-up, 9.3% (420/4492) reported CKP, and 12.0% (537/4471) reported SKD. The most important predictor of CKP at 2-year follow-up was having significant pain before surgery (adjusted odds ratio, 4.10; P <.001). The most important predictor of SKD at 2-year follow-up was the use of a BTB autograft rather than a hamstring tendon autograft (21.3% vs 9.4%, respectively; adjusted odds ratio, 3.12; P <.001). There was no difference between the BTB and hamstring tendon grafts in terms of CKP (9.9% vs 9.2%, respectively; P =.494) or in absolute values of the KOOS Pain (mean, 88.7 vs 89.0, respectively; P =.37) and KOOS Symptoms (mean, 82.5 vs 82.1, respectively; P =.49) subscales. Conclusion: At 2-year follow-up after primary ACL reconstruction, 9.3% of patients reported CKP, and 12.0% reported SKD. The BTB autograft was associated with difficulty with kneeling, but it did not result in a more painful or symptomatic knee compared with the hamstring tendon autograft. [ABSTRACT FROM AUTHOR]

Background: Chronic full-thickness rotator cuff tears (FTRCTs) represent a major clinical concern because they show highly compromised healing capacity. Purpose: To evaluate the efficacy of using a 3-dimensional (3D) bioprinted scaffold with human umbilical cord blood (hUCB)–mesenchymal stem cells (MSCs) for regeneration of chronic FTRCTs in a rabbit model. Study Design: Controlled laboratory study. Methods: A total of 32 rabbits were randomly assigned to 4 treatment groups (n = 8 per group) at 6 weeks after a 5-mm FTRCT was created on the supraspinatus tendon. Group 1 (G1-SAL) was transplanted with normal saline. Group 2 (G2-MSC) was transplanted with hUCB-MSCs (0.2 mL, 1 × 106) into FTRCTs. Group 3 (G3-3D) was transplanted with a 3D bioprinted construct without MSCs, and group 4 (G4-3D+MSC) was transplanted with a 3D bioprinted construct containing hUCB-MSCs (0.2 mL, 1 × 106 cells) into FTRCTs. All 32 rabbits were euthanized at 4 weeks after treatment. Examination of gross morphologic changes and histologic results was performed on all rabbits after sacrifice. Motion analysis was also performed before and after treatment. Results: In G4-3D+MSC, newly regenerated collagen type 1 fibers, walking distance, fast walking time, and mean walking speed were greater than those in G2-MSC based on histochemical and motion analyses. In addition, when compared with G3-3D, G4-3D+MSC showed more prominent regenerated tendon fibers and better parameters of motion analysis. However, there was no significant difference in gross tear size among G2-MSC, G3-3D, and G4-3D+MSC, although these groups showed significant decreases in tear size as compared with the control group (G1-SAL). Conclusion: Findings of this study show that a tissue engineering strategy based on a 3D bioprinted scaffold filled with hUCB-MSCs can improve the microenvironment for regenerative processes of FTRCT without any surgical repair. Clinical Relevance: In the case of rotator cuff tear, the cell loss of the external MSCs can be increased by exposure to synovial fluid. Therefore, a 3D bioprinted scaffold in combination with MSCs without surgical repair may be effective in increasing cell retention in FTRCT. [ABSTRACT FROM AUTHOR]

Background: The patellar tendon is often considered the "gold standard" graft for reducing the risk of graft rupture after anterior cruciate ligament (ACL) reconstruction. However, its use may also be associated with an increased risk of injury to the contralateral ACL. Purpose: To clarify the association between graft choice and the risk of revision and contralateral ACL reconstruction. Study Design: Cohort study; Level of evidence, 2. Methods: Prospective data captured by the New Zealand ACL Registry between April 2014 and December 2018 were reviewed. All primary ACL reconstructions performed using either a hamstring tendon or patellar tendon autograft were included. Cox regression survival analysis adjusting for patient factors was performed to compare the risk of revision and contralateral ACL reconstruction between the hamstring tendon graft and the patellar tendon graft. Results: A total of 7155 primary ACL reconstructions were reviewed, of which 5563 (77.7%) were performed using a hamstring tendon graft and 1592 (22.3%) were performed using a patellar tendon graft. Patients with a hamstring tendon graft had a revision rate of 2.7% compared with 1.3% in patients with a patellar tendon graft (adjusted hazard ratio [HR], 2.51; 95% CI, 1.55-4.06; P <.001). The patellar tendon graft was associated with an increased risk of contralateral ACL reconstruction compared with the hamstring tendon graft (adjusted HR, 1.91; 95% CI, 1.15-3.16; P =.012). The number needed to treat (NNT) with a patellar tendon graft to prevent 1 revision was 73.6. However, the NNT with a hamstring tendon graft to prevent 1 contralateral reconstruction was 116.3. Conclusion: Use of a patellar tendon graft reduced the risk of graft rupture but was associated with an increased risk of injury to the contralateral ACL. Adequate rehabilitation and informed decision making on return to activity and injury prevention measures may be important in preventing subsequent injury to the healthy knee. [ABSTRACT FROM AUTHOR]

Background: Direct impacts with the head (linear acceleration or pressure) and inertial loading of the head (rotational acceleration or strain) have been postulated as the 2 major mechanisms of head-related injuries such as concussion. Although data are accumulating for soccer and American football, there are no published data for nonhelmeted collision sports such as rugby union. Purpose: To quantify head impacts via instrumented mouthguard acceleration analyses for rugby union players over a season of matches. Study Design: Descriptive epidemiology study. Methods: Data on impact magnitude and frequency were collected with molded instrumented mouthguards worn by 38 premier amateur senior rugby players participating in the 2013 domestic season of matches. Results: A total of 20,687 impacts >10g (range, 10.0-164.9g) were recorded over the duration of the study. The mean ± SD number of impacts per player over the duration of the season of matches was 564 ± 618, resulting in a mean ± SD of 95 ± 133 impacts to the head per player, per match over the duration of the season of matches. The impact magnitudes for linear accelerations were skewed to the lower values (Sp = 3.7 ± 0.02; P<.001), with a mean linear acceleration of 22.2 ± 16.2g. Rotational accelerations were also skewed to the lower values (Sp = 2.0 ± 0.02; P < .001), with a mean rotational acceleration of 3902.9 ± 3948.8 rad/s2. Conclusion: The acceleration magnitudes and number of head impacts in amateur rugby union players over a season of matches, measured via instrumented mouthguard accelerations, were higher than for most sports previously reported. Mean linear acceleration measured over a season of matches was similar to the mean linear accelerations previously reported for youth, high school, and collegiate American football players but lower than that for female youth soccer players. Mean rotational acceleration measured over a season of matches was similar to mean rotational accelerations for youth, high school, and collegiate American football players but less than those for female youth soccer players, concussed American collegiate players, collegiate American football players, and professional American football players. [ABSTRACT FROM AUTHOR]