Purpose Button implants with either a fixed-loop device (FLD) or adjustable-loop device (ALD) are used frequently in Anterior Cruciate Ligament Reconstruction (ACLR). Since revision ACLR is associated with poorer clinical outcomes, it is important to investigate the difference in risk of revision between FLDs and ALDs. Therefore, this paper aims to systematically assess the risk of revision ACLR between ALDs and FLDs as well as secondary outcomes such as knee stability and patient reported outcomes (PROMs). Methods The online databases Embase, Medline (PubMed), and SPORTDiscus were searched, comparing FLDs and ALDs for femoral fixation in patients undergoing primary ACLR with hamstring autografts. Risk of bias was assessed with the ROBINS-I tool for non-randomised studies. Due to heterogeneity a meta-analysis on revision rates were not possible. A random-effect meta-analysis was performed for the secondary outcomes and the quality of evidence was evaluated using the GRADE approach. Results Fifteen cohort studies with a total of 2686 patients were included. None of the studies found a clinical difference between ALDs and FLDs in either revision rates, knee stability or PROMS. However, the quality of evidence was graded “very low” due to study designs, risk of bias, and heterogeneity. Conclusion Studies of better quality are needed to investigate the risk of revision ACLR between ALDs and FLDs. There was no difference in knee stability and PROMs between the ALDs and FLDs; however, the interpretation of these results is challenging due to low quality of evidence. Level of evidence Level III.

Purpose Button implants with an adjustable-loop device (ALD) are often used in anterior cruciate ligament reconstruction (ACLR). Clinical research comparing ALDs with ixed-loop devices (FLD) has mainly been conducted in small patient populations with short follow-up times. To determine whether ALDs are safe to use in ACLR, a non-inferiority study with a large sample population and a long follow-up period would be beneicial. This study compared ALDs with FLDs to determine non-inferior revision surgery rates, knee stability, and patient-reported outcomes (PROM) in ACLRs. Methods This non-inferiority register-based cohort study was conducted using data from the Danish Knee Ligament Reconstruction Registry (DKRR). A total of 12,723 patients > 15 years of age with primary ACLR using hamstring tendon autografts and either an FLD or ALD for femoral ixation were included: 9719 patients were in the FLD group, and 3014 patients were in the ALD group. The primary outcome was revision ACLR with a non-inferiority margin for ALDs at 4% at the 2-year follow-up. The secondary outcomes were anterior and rotatory knee stability and PROMs based on the Knee Injury and Osteoarthritis Outcome Score (KOOS) at the 1-year follow-up. ResultsThe crude cumulative revision rates in ALD implants at 2 and 5 years were 2.1% (95% CI 1.62-2.68) and 5.0% (95% CI 4.22-5.96), respectively. In the FLD group, the rates were 2.2% (95% CI 1.89-2.48) at 2 years and 4.7% (95% CI 4.31-5.20) at 5 years. The 1-year side-to-side diferences were 0.97 mm (95% CI 0.90-1.03) in the ALD group and 1.45 mm (95% CI 1.41-1.49) in the FLD group. In the FLD group, 13% had a positive pivot shift, and in the ALD group, 6% had a positive pivot shift. There were no diferences in KOOS. Conclusion ALDs were non-inferior to FLDs regarding revision rates, knee stability, and patient-reported outcomes. Based on this conclusion, ALDs are safe to use for femoral ixation in ACLR. Level of evidence III.

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Purpose To investigate the effect of bone-marrow stimulation (BMS) on subchondral bone plate morphology and remodeling compared to untreated subchondral bone in a validated minipig model. Methods Three Göttingen minipigs received BMS with drilling as treatment for two chondral defects in each knee. The animals were euthanized after six months. Follow-up consisted of a histological semiquantitative evaluation using a novel subchondral bone scoring system and micro computed tomography (µCT) of the BMS subchondral bone. The histological and microstructural properties of the BMS-treated subchondral bone were compared to that of the adjacent healthy subchondral bone. Results The µCT analysis showed that subchondral bone treated with BMS had significantly higher connectivity density compared to adjacent untreated subchondral bone (26 1/mm3 vs. 21 1/mm3, P = 0.048). This was the only microstructural parameter showing a significant difference. The histological semiquantitative score differed significantly between the subchondral bone treated with BMS and the adjacent untreated subchondral (8.0 vs. 10 P = < 0.001). Surface irregularities were seen in 43% and bone overgrowth in 27% of the histological sections. Only sparse formation of bone cysts was detected (1%). Conclusions BMS with drilling does not cause extensive changes to the subchondral bone microarchitecture. Furthermore, the morphology of BMS subchondral bone resembled that of untreated subchondral bone with almost no formation of bone cyst, but some surface irregularities and bone overgrowth.