Whip-Lock Stitch Is Biomechanically Superior to Whipstitch for Semitendinosus Tendons.

Purpose: To assess the biomechanical performance of different stitching methods using a suturing device by comparing the elongation, stiffness, failure load, and time to stitch completion in cadaveric semitendinosus tendons (STs) and quadriceps tendons (QTs). Methods: A total of 24 STs and 16 QTs were harvested from cadaveric knee specimens (N = 40). Samples were randomly divided into 2 groups: whipstitch (WS) and whip-lock (WL) stitch. Both tendon ends were clamped to a graft preparation stand, and a 2-part needle was used to place 5 stitches, each 0.5 cm apart. Stitching time was recorded. Samples were preconditioned and then underwent cyclic loading from 50 to 200 N at 1 Hz for 500 cycles, followed by load-to-failure testing at 20 mm/min. Stiffness (in newtons per millimeter), ultimate failure load (in newtons), peak-to-peak displacement (in millimeters), elongation (in millimeters), and failure displacement (in millimeters) were recorded. Results: Completion of the WS was significantly faster than the WL stitch in the ST (P < .001) and QT (P = .004). For the ST, the WL stitch exhibited higher ultimate failure loads and construct stiffness than the WS. Regarding the QT, the WL stitch showed higher stiffness and displacement than the WS; however, the ultimate failure load was higher for the WS in the QT. The ultimate failure load in the QT was higher than that in the ST for both stitches. In the ST, only 25% of WSs and 100% of WL stitches failed due to suture breakage. In the QT, suture breakage led to the failure of 100% of both the WL stitches and WSs. Conclusions: In the ST, the WL stitch resulted in improved biomechanical performance through higher ultimate load and fewer failures from tissue damage compared with the WS. In the QT, both the WS and the WL stitch showed similar biomechanical performance with ultimate failure loads above established clinical failure thresholds. Clinical Relevance: Various types of ligament and tendon injuries require suturing to enable repair or reconstruction. The success of ligament or tendon surgery often relies on soft-tissue quality. It is important to investigate the biomechanical properties of stitching techniques that help preserve soft-tissue quality as a step to determining their clinical suitability.

Cells Remain Viable When Collected With an In-Line-Suction Tissue Collector From Byproducts of Anterior Cruciate Ligament Reconstruction Surgery.

Purpose: To investigate the viability of cells collected with an in-line-suction autologous tissue collector from the tissue byproducts of arthroscopic anterior cruciate ligament (ACL) reconstruction, to characterize cells from different tissue types, and to identify mesenchymal stem cells. Methods: Patients aged 14 to 50 years with ACL injuries requiring arthroscopic reconstruction surgery were offered enrollment and screened for participation. In total, 12 patients were enrolled in the descriptive laboratory study. Arthroscopic byproduct tissue was collected with an in-line-suction autologous tissue collector from 4 intraoperative collection sites for each patient: ACL stump, ACL fat pad, notchplasty debris, and tunnel drilling debris. All tissue samples were digested using collagenase, and the derived cellular populations were analyzed in vitro, characterizing cellular viability, proliferative potential, qualitative multipotent differentiation capacity, and cell-surface marker presence. Results: An equivalent mass of arthroscopic byproduct tissue was taken from each of the 4 intraoperative collection sites (1.12-1.61 g, P = .433), which all showed an average viability of at least 99.95% and high average total nucleated cells (≥1.37 × 107 cells/mL). No significant differences in collected mass (P = .433), cellular viability (P = .880), or total nucleated cells (P = .692) were observed between the 4 byproduct tissues. The byproduct tissues did exhibit significant differences in monocyte (P = .037) and red blood cell (P = .038) concentrations, specifically with greater values present in the ACL stump tissue. Cells from all byproduct tissues adhered to plastic cell culture flasks. Significant differences were found between colony-forming unit fibroblast counts of the 4 byproduct tissues when plated at 106 (P = .003) and 103 (P = .016) cells as the initial seeding density. There was a significant relationship found between both the starting concentration (χ2 = 32.7, P < .001) and the byproduct tissue type (χ2 = 30.4, P < .001) to the presence of ≥80% confluency status at 10 days. Cells obtained from all 4 byproduct tissues qualitatively showed positive tri-lineage (adipocyte, osteoblast, chondroblast) differentiation potential compared with negative controls under standardized in vitro differentiation conditions. Cells derived from all 4 byproduct tissues expressed cell-surface antigens CD105+, CD73+, CD90+, CD45-, CD14-, and CD19- (>75%), and did not express CD45 (<10%). There were no statistically significant differences in cell-surface antigens between the four byproduct tissues. Conclusions: This descriptive laboratory study demonstrated that cells derived from arthroscopic byproduct tissues of ACL reconstruction remain viable when collected with an in-line-suction autologous tissue collector and these cells meet the ISCT criteria to qualify as mesenchymal stem cells. Clinical Relevance: It is known that viable mesenchymal stem cells reside in byproduct tissue of anterior cruciate ligament reconstruction surgery (ACLR). Practical methods to harvest these cells at the point of care require further development. This study validates the use of an in-line-suction autologous tissue collector for the harvest of viable mesenchymal stem cells after ACLR.

Augmentation of ACL Autograft Reconstruction With an Amnion Collagen Matrix Wrap and Bone Marrow Aspirate Concentrate: A Pilot Randomized Controlled Trial With 2-Year Follow-up.

Background: It is theorized that the lack of a synovial lining after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) contributes to slow ligamentization and possible graft failure. Whether graft maturation and incorporation can be improved with the use of a scaffold requires investigation. Purpose: To evaluate the safety and efficacy of wrapping an ACL autograft with an amnion collagen matrix and injecting bone marrow aspirate concentrate (BMAC), quantify the cellular content of the BMAC samples, and assess 2-year postoperative patient-reported outcomes. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: A total of 40 patients aged 18 to 35 years who were scheduled to undergo ACLR were enrolled in a prospective single-blinded randomized controlled trial with 2 arms based on graft type: bone-patellar tendon-bone (BTB; n = 20) or hamstring (HS; n = 20). Participants in each arm were randomized into a control group who underwent standard ACLR or an intervention group who had their grafts wrapped with an amnion collagen matrix during graft preparation, after which BMAC was injected under the wrap layers after implantation. Postoperative magnetic resonance imaging (MRI) mapping/processing yielded mean T2* relaxation time and graft volume values at 3, 6, 9, and 12 months. Participants completed the Single Assessment Numeric Evaluation Score, Knee injury and Osteoarthritis Outcome Score, and pain visual analog scale. Statistical linear mixed-effects models were used to quantify the effects over time and the differences between the control and intervention groups. Adverse events were also recorded. Results: No significant differences were found at any time point between the intervention and control groups for BTB T2* (95% CI, -1.89 to 0.63; P = .31), BTB graft volume (95% CI, -606 to 876.1; P = .71), HS T2* (95% CI, -2.17 to 0.39; P = .162), or HS graft volume (95% CI, -11,141.1 to 351.5; P = .28). No significant differences were observed between the intervention and control groups of either graft type on any patient-reported outcome measure. No adverse events were reported after a 2-year follow-up. Conclusion: In this pilot study, wrapping a graft with an amnion collagen matrix and injecting BMAC appeared safe. MRI T2* values and graft volume of the augmented ACL graft were not significantly different from that of controls, suggesting that the intervention did not result in improved graft maturation. Registration: NCT03294759 (ClinicalTrials.gov identifier).

Platelet-Rich Plasma Devices Can Be Used to Isolate Stem Cells From Synovial Fluid at the Point of Care.

PURPOSE: To assess whether point-of-care devices designed for collecting cellular components from blood or bone marrow could be used to isolate viable stem cells from synovial fluid. METHODS: Male and female patients older than 18 years old with either an acute, anterior cruciate ligament (ACL) injury or knee osteoarthritis (OA) with a minimum estimated 20 mL of knee effusion volunteered. Ten patients with an ACL injury and 10 patients with OA were enrolled. Two milliliters of collected synovial effusion were analyzed and cultured for cellular content. The remaining fluid was combined with whole blood and processed using a buffy-coat based platelet-rich plasma (PRP) processing system. Specimens were analyzed for cell counts, colony-forming unit (CFU) assays, differentiation assays, and flow cytometry. RESULTS: ACL effusion fluid contained 42.1 ± 20.7 CFU/mL and OA effusion fluid contained 65.4 ± 42.1 CFU/mL. After PRP processing, the counts in ACL-PRP were 101.6 ± 66.1 CFU/mL and 114.8 ± 73.4 CFU/mL in the OA-PRP. Cells showed tri-lineage differentiation potential when cultured under appropriate parameters. When analyzed with flow cytometry, >95% of cells produced with culturing expressed cell surface markers typically expressed by known stem cell populations, specifically CD45-, CD73+, CD29+, CD44+, CD105+, and CD90+. CONCLUSIONS: Multipotent viable stem cells can be harvested from knee synovial fluid, associated with an ACL injury or OA, and concentrated with a buffy coat-based PRP-processing device. CLINICAL RELEVANCE: PRP devices can be used to harvest stem cells from effusion fluids. Methods to use effusion fluid associated with an ACL injury and OA should be investigated further.

Calcium Phosphate Bone Void Filler Increases Threaded Suture Anchor Pullout Strength: A Biomechanical Study.

PURPOSE: To compare the response to cyclical loading and ultimate pull-out strength of threaded suture anchor with and without calcium phosphate bone void filler augmentation in a polyurethane foam block model and in vitro proximal humerus cadaveric model. METHODS: This controlled biomechanical study consisted of 2 parts: (1) preliminary polyurethane foam block model, and (2) in vitro cadaveric humeri model. The preliminary foam block model intended to mimic osteoporotic bone using a 0.12 g/mL foam material. Half of the foam block models were first filled with injectable calcium phosphate bone substitute material (CP-BSM), whereas the other half were not augmented with CP-BSM. Each specimen was then instrumented with a threaded suture anchor. The same technique and process was performed in a matched cadaveric humeri model. Testing then consisted of a stepwise, increasing axial load protocol for a total of 40 cycles. If the anchor remained intact after cyclic loading, the repair was loaded to failure. The number of completed cycles, failure load, and failure modes were compared between groups. RESULTS: Average pull-out strength for suture anchor with CP-BSM in the osteoporotic foam block model was significantly higher at 332.68 N ± 47.61 compared with the average pull-out strength of suture anchor without CP-BSM at 144.38 N ± 14.58 (P = .005). In the matched cadaveric humeri model, average pull-out strength for suture anchor with CP-BSM was significantly higher at 274.07 N ± 102.07 compared with the average pull-out strength of suture anchor without CP-BSM at 138.53 N ± 109.87 (P = .029). CONCLUSIONS: In this time zero, biomechanical study, augmentation of osteoporotic foam block and cadaveric bone with calcium phosphate bone substitute material significantly increases pull-out strength of threaded suture anchors. CLINICAL RELEVANCE: Considering concerns about suture anchor pull-out from osteoporotic bone, augmentation with calcium phosphate bone substitute material increases load to failure resistance.

3-T MRI mapping is a valid in vivo method of quantitatively evaluating the anterior cruciate ligament: rater reliability and comparison across age.

OBJECTIVE: As biologic augmentation methods emerge, objective measures of soft tissues are necessary for developmental study. The purpose of this study was to develop a quantitative MRI mapping protocol for the ACL. The objectives were (1) to provide age-based T2 relaxation, T2* relaxation, and volume values in healthy individuals, (2) to establish the intra-rater and inter-rater reliability of ACL mapping, and (3) to determine whether 3-T or 7-T MRI is more appropriate for future clinical trials. MATERIALS AND METHODS: Thirty healthy participants, aged 18-62, asymptomatic for knee pathology and without history of knee injury underwent both a 3-T and 7-T MRI. Manual image mapping of the anterior cruciate ligament was performed by two observers and processed to obtain T2, T2*, and volume values. Analysis of variance and two-way random effects model were used to calculate statistical significance and intraclass correlation coefficients. RESULTS: Across all participants, 3-T and 7-T mean T2, T2* and volume values were 37.1 ± 7.9 and 39.7 ± 6.2 ms (p = 0.124), 10.9 ± 1.3 and 10.9 ± 0.9 ms (p = 0.981), and 2380 ± 602 and 2484 ± 736 mm3 (p = 0.551), respectively. The T2, T2*, and volume did not vary between age cohorts (p > 0.05). Excellent inter-rater and intra-rater reliability regarding T2 and T2* values was found. While ACL volume exhibited good inter-rater reliability and excellent intra-rater reliability. CONCLUSIONS: T2 relaxation values and ACL volume do not vary with age and therefore can be used as a quantifiable, non-invasive method to assess ACL graft maturation. 7-T MRI analysis was not superior to 3-T MRI analysis, suggesting that 3-T MRI is practical and capable for future comparative studies.

A Biomechanical Assessment of Biceps Femoris Repair Techniques.

BACKGROUND: Knee injuries encountered in clinical practice can involve avulsions of the biceps femoris from the fibula and proximal tibia. Advances in tendon repair methods now allow for repairs with increased surface areas using modern suture anchor techniques. Despite descriptions of repair techniques, there are no biomechanical studies on the biceps femoris for comparison. PURPOSE/HYPOTHESIS: The objective of this controlled laboratory study was to determine the failure load of the native biceps femoris distal insertion and to evaluate modern repair techniques. Our hypothesis was 2-fold: (1) Suture repairs to the tibia and fibula would perform better on tensile testing than repairs to the fibula alone, and (2) complex bridge repairs, similar to those frequently used in rotator cuff surgery, would perform better on tensile testing than simple repairs. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 40 paired, fresh-frozen cadaveric specimens were dissected, identifying the biceps femoris and its insertion on the proximal tibia and fibula. The native biceps femoris footprint was left intact in 8 specimens and tested to failure on a uniaxial materials testing machine evaluating tensile properties, while in the other 32 specimens, the biceps femoris insertion was dissected using a No. 15 scalpel blade, underwent repair, and was then tested to failure on a uniaxial materials testing machine evaluating tensile properties. Four repair constructs were evaluated, with 8 specimens allocated for each: construct 1 involved a simple repair (ie, passing suture through tissue in a running Krackow fashion and tying at the anchor site) to the fibula with 2 suture anchors, construct 2 involved a simple repair to the fibula and tibia with 3 suture anchors, construct 3 was a fibular repair with a tibial suture bridge involving the fibula and tibia and 3 suture anchors, construct 4 involved a transosseous repair through the fibula and 1 suture anchor on the tibia. Analysis of variance was used to evaluate for significance of the mean failure load and stiffness between groups. RESULTS: The mean (±95% CI) failure loads were the following: native biceps femoris, 1280 ± 247.0 N; simple fibular repair, 173 ± 84.6 N; simple fibular and tibial repair, 176 ± 48.1 N; fibular repair with tibial suture bridge, 191 ± 78.5 N; and transosseous repair, 327 ± 66.3 N. The mean stiffness values were the following: native, 46 ± 13.0 N/mm; simple fibular repair, 16 ± 5.1 N/mm; simple fibular and tibial repair, 14 ± 5.4 N/mm; fibular repair with tibial suture bridge, 13 ± 2.8 N/mm; and transosseous repair, 15 ± 2.5 N/mm. Interconstruct comparison of failure loads revealed no statistical difference between constructs utilizing anchors alone. The transosseous repair showed a significant difference for the failure load when compared with each anchor repair construct (P = .02, .02, and .04 for constructs 1, 2, and 3, respectively). Interconstruct comparison of stiffness revealed no statistical difference between all constructs (P > .86). None of the repair techniques re-created the failure load or stiffness of the native biceps femoris tendon (P = .02). CONCLUSION: In this biomechanical study, no difference was found between the mean failure loads of different biceps femoris repair constructs involving suture anchors alone and No. 2 braided polyester and ultra-high-molecular-weight polyethylene suture. A technique involving transosseous fibular tunnels and 2-mm suture tape illustrated a greater mean failure load than repairs relying on suture anchors for fixation. CLINICAL RELEVANCE: Understanding the tensile performance of biceps femoris repair constructs aids clinicians with preoperative and intraoperative decisions. Current biceps femoris repair techniques do not approximate the native strength of the tendon. A transosseous style of repair offers the highest failure load.

Viable Stem Cells Are in the Injury Effusion Fluid and Arthroscopic Byproducts From Knee Cruciate Ligament Surgery: An In Vivo Analysis.

PURPOSE: To examine the number of viable stem cells contained in the postinjury effusion fluid and the waste byproducts of arthroscopic cruciate ligament surgery. METHODS: This study included patients older than 18 years of age with acute (<5 weeks old) cruciate ligament injuries requiring arthroscopic surgery. The postinjury effusion fluid (effusion fluid), fat pad and cruciate ligament stump debridement tissue (byproduct tissue), and arthroscopic fluid collected during fat pad and/or stump debridement (byproduct fluid) were collected at the time of surgery from 30 individuals. Specimens were analyzed, investigating cell viability, nucleated cell counts, cell concentrations, colony-forming unit assays, and flow cytometry. Samples from the first 20 individuals were collected in small specimen containers, and samples from the last 10 individuals were collected in larger specimen containers. RESULTS: Cells of the injury effusion exhibited the greatest viability (86.4 ± 1.31%) when compared with the small volume harvest byproduct tissue (50.2 ± 2.5%, P = .0001), small volume harvest byproduct fluid (48.8 ± 1.88%, P = .0001), large volume harvest byproduct tissue (70.1 ± 5.6%, P = .0001), and large volume harvest byproduct fluid (60.3 ± 3.41%, P = .0001). The culture analysis of fibroblast colony-forming units found on average 1916 ± 281 progenitor cells in the effusion fluid, 2488 ± 778 progenitor cells in the byproduct tissue, and 2357 ± 339 progenitor cells in the byproduct fluid. Flow cytometry confirmed the presence of immature cells and the presence of cells with markers typically expressed by known stem cell populations. CONCLUSIONS: Viable stem cells are mobilized to the postinjury effusion at the time of cruciate ligament injury and can be found in the byproduct waste of cruciate ligament surgery. CLINICAL RELEVANCE: The methodology around effusion fluid and byproduct tissue capture during cruciate ligament surgery should be investigated further. Cell amounts available from these tissues with current technologies are not sufficient for immediate evidence-based clinical application.

Biomechanical Comparison of Parallel and Crossed Suture Repair for Longitudinal Meniscus Tears.

BACKGROUND: Longitudinal meniscus tears are commonly encountered in clinical practice. Meniscus repair devices have been previously tested and presented; however, prior studies have not evaluated repair construct designs head to head. This study compared a new-generation meniscus repair device, SpeedCinch, with a similar established device, Fast-Fix 360, and a parallel repair construct to a crossed construct. Both devices utilize self-adjusting No. 2-0 ultra-high molecular weight polyethylene (UHMWPE) and 2 polyether ether ketone (PEEK) anchors. HYPOTHESIS: Crossed suture repair constructs have higher failure loads and stiffness compared with simple parallel constructs. The newer repair device would exhibit similar performance to an established device. STUDY DESIGN: Controlled laboratory study. METHODS: Sutures were placed in an open fashion into the body and posterior horn regions of the medial and lateral menisci in 16 cadaveric knees. Evaluation of 2 repair devices and 2 repair constructs created 4 groups: 2 parallel vertical sutures created with the Fast-Fix 360 (2PFF), 2 crossed vertical sutures created with the Fast-Fix 360 (2XFF), 2 parallel vertical sutures created with the SpeedCinch (2PSC), and 2 crossed vertical sutures created with the SpeedCinch (2XSC). After open placement of the repair construct, each meniscus was explanted and tested to failure on a uniaxial material testing machine. All data were checked for normality of distribution, and 1-way analysis of variance by ranks was chosen to evaluate for statistical significance of maximum failure load and stiffness between groups. Statistical significance was defined as P < .05. RESULTS: The mean maximum failure loads ± 95% CI (range) were 89.6 ± 16.3 N (125.7-47.8 N) (2PFF), 72.1 ± 11.7 N (103.4-47.6 N) (2XFF), 71.9 ± 15.5 N (109.4-41.3 N) (2PSC), and 79.5 ± 25.4 N (119.1-30.9 N) (2XSC). Interconstruct comparison revealed no statistical difference between all 4 constructs regarding maximum failure loads (P = .49). Stiffness values were also similar, with no statistical difference on comparison (P = .28). CONCLUSION: Both devices in the current study had similar failure load and stiffness when 2 vertical or 2 crossed sutures were tested in cadaveric human menisci. CLINICAL RELEVANCE: Simple parallel vertical sutures perform similarly to crossed suture patterns at the time of implantation.

Distal Insertions of the Biceps Femoris: A Quantitative Analysis.

BACKGROUND: Avulsion of the biceps femoris from the fibula and proximal tibia is encountered in clinical practice. While the anatomy of the primary posterolateral corner structures has been qualitatively and quantitatively described, a quantitative analysis regarding the insertions of the biceps femoris on the fibula and proximal tibia is lacking. PURPOSE: To quantitatively assess the insertions of the biceps femoris, fibular collateral ligament (FCL), and anterolateral ligament (ALL) on the fibula and proximal tibia as well as establish relationships among these structures and to pertinent surgical anatomy. STUDY DESIGN: Descriptive laboratory study. METHODS: Dissections were performed on 12 nonpaired, fresh-frozen cadaveric specimens identifying the biceps femoris, FCL, and ALL, and their insertions on the proximal tibia and fibula. The footprint areas, orientations, and distances from relevant osseous landmarks were measured using a 3-dimensional coordinate measurement device. RESULTS: Dissection produced 6 easily identifiable and reproducible anatomic footprints. Tibial footprints included the insertion of the ALL and an insertion of the biceps femoris (TBF). Fibular footprints included the insertion of the FCL, a distal insertion of the biceps femoris (DBF), a medial footprint of the biceps femoris (MBF), and a proximal footprint of the biceps femoris (PBF). The mean area of these footprints (95% CI) was as follows: ALL, 53.0 mm(2) (38.4-67.6); TBF, 93.9 mm(2) (72.0-115.8); FCL, 86.8 mm(2) (72.3-101.2); DBF, 119 mm(2) (91.1-146.9); MBF, 46.8 mm(2) (29.0-64.5); and PBF, 215 mm(2) (192.4-237.5). The mean distance (95% CI) from the Gerdy tubercle to the center of the ALL footprint was 24.3 mm (21.6-27.0) and to the center of the TBF was 22.5 mm (21.0-24.0). The center of the DBF was 8.68 mm (7.0-10.3) from the anterior border of the fibula, the center of the FCL was 14.6 mm (12.5-16.7) from the anterior border of the fibula and 20.7 mm (19.0-22.4) from the tip of the fibular styloid, and the center of the PBF was 8.96 mm (8.2-9.7) from the tip of the fibular styloid. CONCLUSION: A tibial footprint, distal fibular footprint, medial fibular footprint, and proximal fibular footprint were all consistent components of the insertion of the biceps femoris. Consistent relationships existed between the biceps femoris and insertions of the ALL and FCL. CLINICAL RELEVANCE: The size of these footprints and distances from pertinent surgical landmarks will guide repairs of biceps femoris avulsion injuries.

Biomechanical comparison of arthroscopic repair constructs for radial tears of the meniscus.

BACKGROUND: Radial tears of the meniscus represent a challenging clinical scenario because benign neglect and partial meniscectomy have both been shown to have negative biomechanical and long-term clinical consequences. HYPOTHESIS: Complex suture repair constructs have higher failure loads and stiffness values compared with simple constructs. STUDY DESIGN: Controlled laboratory study. METHODS: After radial transection of human cadaveric menisci, simulated tears were repaired arthroscopically by use of 1 of 4 repair constructs: (1) 2 inside-out horizontal sutures, (2) 2 all-inside horizontal sutures, (3) an all-inside Mason-Allen construct consisting of 4 sutures, or (4) an all-inside construct consisting of a figure-of-8 suture plus 1 horizontal suture. Meniscus specimens were harvested and tested to failure on an Instron machine. The Kruskal-Wallis test was used to evaluate for significance of maximal failure load and stiffness between groups. RESULTS: The mean maximum failure loads were 64 ± 20 N (inside-out horizontal construct), 75 ± 16 N (all-inside horizontal construct), 86 ± 19 N (Mason-Allen construct), and 113 ± 22 N (figure-of-8 plus horizontal construct). Interconstruct comparison revealed a statistically significant difference between the figure-of-8 plus horizontal construct and all 3 remaining constructs (P < .02) as well as the Mason-Allen construct when compared with the inside-out horizontal construct (P < .01). Statistical significance was not found between the all-inside horizontal construct and the Mason-Allen construct or between the all-inside horizontal construct and the inside-out horizontal construct (P = .2 and .7, respectively). Stiffness values were lower for the inside-out construct compared with the all-inside constructs (P < .05). CONCLUSION: Complex all-inside repair constructs had significantly higher failure loads than a conventional, simple inside-out suture repair construct for repair of radial meniscal tears. Stiffness values among the all-inside groups were greater than those for the inside-out group. CLINICAL RELEVANCE: Arthroscopic techniques are presented to produce stronger radial meniscal tear repairs.

Biomechanical comparison of arthroscopic repair constructs for meniscal root tears.

BACKGROUND: Complete meniscal root tears render the meniscus nonfunctional. Repair constructs have been presented and tested; however, prior studies have evaluated suture patterns placed ex vivo without simulating an in vivo surgical setting. This study introduces a new double-locking loop suture pattern and compares its biomechanical properties and execution time with commonly used suture patterns. All constructs were performed using an all-inside arthroscopic technique. HYPOTHESIS: Complex suture repair constructs have higher failure loads, stiffness, and execution times compared with simple constructs. STUDY DESIGN: Controlled laboratory study. METHODS: Sutures were placed arthroscopically into the posterior horn root region of the medial and lateral menisci in 21 cadaveric knees. Four repair constructs were evaluated: 2 simple sutures (2SS), 1 inverted mattress suture (1MS), 1 double-locking loop suture (1DLS), and 2 double-locking loop sutures (2DLS). In total, 40 posterior meniscal roots were tested, with 10 trials for each construct. After arthroscopic placement of the root repair constructs, each meniscus was explanted and tested to failure on a uniaxial materials testing machine. The Kruskal-Wallis test was used to evaluate for the significance of maximum failure loads and stiffness between groups. RESULTS: The mean maximum failure loads were 137 ± 49 N (2SS), 126 ± 44 N (1MS), 186 ± 43 N (1DLS), and 368 ± 76 N (2DLS). Interconstruct comparison revealed a statistical difference between 2DLS and all 3 remaining constructs (P < .01) and 1DLS when compared with 2SS and 1MS (P < .01 for both). Statistical significance was not found between 2SS and 1MS (P = .8). The mean times for repair of the 4 fixation techniques were 1.8 ± 0.9 minutes (2SS), 2.4 ± 1.9 minutes (1MS), 4.7 ± 2.0 minutes (1DLS), and 5.4 ± 0.6 minutes (2DLS). CONCLUSION: The double-locking loop suture repair technique had significantly higher failure loads compared with the 3 other methods tested. As the complexity of repair constructs increases, failure loads and surgical times increase. CLINICAL RELEVANCE: Complex suture patterns can be placed via an all-inside arthroscopic technique delivering higher failure loads for meniscal root repair with little increase in surgical time.