Bone density may affect primary stability of anterior cruciate ligament reconstruction when organic core bone plug fixation technique used

Purpose Core Bone Plug Fixation (CBPF) technique is an implant-less methodology for ACL reconstruction. This study investigates the effect of bone density on CBPF stability to identify the bone quality that is likely to benefit from this technique. Methods Artificial blocks with 160 (Group 1), 240 (Group 2), and 320 (Group 3) kg/m3 densities were used to simulate human bone with diverse qualities. These groups are representative of the elderly, middle age and young people, respectively. A tunnel was made in each test sample using a cannulated drill bit which enabled harvesting the core bone plug intact. Fresh animal tendon grafts were prepared and passed through the tunnel, so the core bone was pushed in to secure the tendon. The fixation stability was tested by applying a cyclic load following by a pullout load until the failure occurred. The selected group was compared with interference screw fixation technique as a gold standard method in ACL reconstruction. Results The Group 2 stiffness and yield strength were significantly larger than Group 1. The graft slippage of Group 1 was significantly less than Group 3. The ultimate strengths were 310 N and 363 N, in Groups 2 and 3, significantly larger than that of Group 1. The ultimate strength in fixation by interference screw was 693.18 N, significantly larger than the bone plug method. Conclusions The stability of CBPF was greatly affected by bone density. This technique is more suitable for young and middle-aged people. With further improvements, the CBPF might be an alternative ACL reconstruction technique for patients with good bone quality. Clinical relevance The CBPF technique offers an implant-less organic ACL reconstruction technique with numerous advantages and likely would speed up the healing process by using the patient’s own bones and tissues rather than any non-biologic fixations.

A Prospective Comparison of 3 Hamstring ACL Fixation Devices - Rigidfix, BioScrew and Intrafix - Randomized Into 4 Groups with a Minimum Follow-Up of 5 Years.

Background: This is a five years follow-up report of some of the new devices for graft fixation. A two years follow-up data was published previously. As there were no statistically or clinically relevant differences in the results two years postoperatively, we hypothesize that after five years of follow-up there is no difference in the outcome after either cross-pin or absorbable interference screw fixation in ACL (anterior cruciate ligament) reconstruction with hamstring tendon autografts.Methods: 120 patients were randomized into four different groups (30 each) for ACL reconstruction with hamstring tendons: group I femoral Rigidfix cross-pin and Intrafix tibial extension sheath with a tapered expansion screw; group II Rigidfix femoral and BioScrew interference screw tibial fixation; group III BioScrew femoral and Intrafix tibial fixation; group IV BioScrew fixation into both tunnels. The evaluation methods were clinical examination, knee scores, and instrumented laxity measurements. Results: In this 5 years follow-up there were 102/120 (85%) patients available, but only 77 (64,2%) attended the clinical examinations. No significant difference between the groups in the clinical results was detected. There was a significant difference in additional procedures between the 2 and 5 years follow-up, group I had six additional procedures between the 2 and 5 years follow-up (P=.041). Conclusion: There was a statistically significant difference in the additional procedures, most in group I (six). None of these procedures found problems with the ACL graft. Other statistically or clinically significant differences in the 5 years follow-up results were not found. Study design: Randomized controlled clinical trial; Level of evidence, 1.Trial registration: ISRCTN registry with study ID ISRCTN34011837. Retrospectively registered 17.4.2020.

Comparison of mechanical properties in interference screw fixation technique and organic anterior cruciate ligament reconstruction method: a biomechanical study

Background Bone and Site Hold Tendon Inside (BASHTI) technique is an organic implant-less technique for anterior cruciate ligament (ACL) reconstruction with some clinical advantages, such as speeding up the healing process, over implantable techniques. The study aims to compare the mechanical properties of BASHTI technique with the conventional interference screw technique. Methods To investigate the mechanical properties, 20 in-vitro experimental tests were conducted. Synthetic dummy bone, along with fresh digital bovine tendons, as a graft, were used for experiments. Three loading steps were applied to all specimens, including a preconditioning, a main cyclic, and a pull-out loading. Results The mechanical characters of an interference screw technique using an 8 mm tendon diameter, including fixation strength, average cyclic stiffness (ACS), and average pull-out stiffness (APS) were found to be 439 ± 132 N, 10.3 ± 5.3 kN/mm, and 109 ± 40 N/mm, respectively. In the case of an interference screw using a 9 mm tendon, the fixation strength, ACS, and APS were obtained 549 ± 87 N, 10.3 ± 4.7 kN/mm, and 91 ± 13 N/mm, respectively. In parallel, the fixation strength, APS, and ACS of BASHTI technique using an 8 mm tendon were 360 ± 123 N, 3.3 ± 0.6 kN/mm, and 79 ± 27 N/mm, respectively, while, for 9 mm tendon 278 ± 103 N, 2.4 ± 1.2 kN/mm, and 111 ± 40 N/mm, were reported for fixation strength, APS, and ACS respectively when BASHTI technique was used. Conclusion About 50% of interference screw samples showed superior mechanical properties compared to BASHTI technique, but in another half of the samples, the differences were not significant (N.S.). However, due to organic advantages of BASHTI technique and lower cost, it could be used as a substitute for interference screw technique, especially where fast recovery is expected.

A BIOMECHANICAL COMPARISON OF MATCHED FOUR-STRAND AND FIVE-STRAND SEMITENDINOSUS-GRACILIS GRAFTS

ABSTRACT Introduction: Recent studies have shown that the likelihood of semitendinosus-gracilis graft rupture is inversely correlated to its diameter. A graft can be prepared in a five-strand or four-strand fashion to increase its diameter. However, the biomechanical superiority of five-strand semitendinosus-gracilis grafts is still under debate. Objective: This study aimed to evaluate the biomechanical characteristics of matched four-strand and five-strand human semitendinosus-gracilis grafts. Methods: We evaluated semitendinosus-gracilis tendons harvested from ten fresh human male and female cadavers, aged 18-60 years. Four-strand or five-strand grafts were prepared with the tendons and fixed to wooden tunnels with interference screws. Each graft was submitted to axial traction at 20 mm/min until rupture; the tests were donor matched. Data were recorded in real time and included the analysis of the area, diameter, force, maximum deformation and stiffness of the grafts. Results: The diameter, area and tunnel size were significantly greater in the five-strand grafts than in the four-strand grafts. There were no significant differences in biomechanical properties. The area and diameter of the graft were positively correlated to stiffness, and inversely correlated to elasticity. There was no significant correlation between graft size and maximum force at failure, maximum deformation or maximum tension. Conclusion: Five-strand hamstring grafts have greater area, diameter and tunnel size than four-strand grafts. There were no significant differences in biomechanical properties. In this model using interference screw fixation, the increases in area and diameter were correlated with an increase in stiffness and a decrease in elasticity. Level of evidence V; biomechanical study.

Dynamic Medial Patellofemoral Ligament Reconstruction in Patellar Instability: A Surgical Technique

Background: Patella instability with recurrent dislocations is a result of various pathologies, for example, patella alta, trochlea dysplasia or medial patellofemoral ligament (MPFL) rupture. The recurrent dislocation rate of conservatively treated chronic patellar instability is high; therefore, it is recommended to manage it surgically. This video presents a new operative approach to stabilize the patella in a dynamic MPFL reconstruction, which addresses the most common complications occurring in static reconstructions: malpositioning and overtensioning the graft. Indications: Surgical indications for the new dynamic procedure mirror the indications for static MPFL reconstruction. This is MPFL insufficiency (patella instability in the first 30° of knee flexion), which is most frequently seen in recurrent lateral patella dislocations. Moreover in very rare cases of first patella dislocation with a patellar instability severity score equal or higher than 4. Technique Description: The dynamic MPFL reconstruction consists of 3 steps: First, detaching and mobilizing the gracilis muscle at its anatomical insertion. Second, redirecting the freed gracilis muscle to its new patellar insertion. Third, reinserting the gracilis muscle at the patella. Results: The dynamic MPFL reconstruction has the advantage of lesser risk of overtensioning and malpositioning the graft. The insertion point of the MPFL surrogate is easier to locate, and the patella is dynamically stabilized through reflectory gracilis muscle contraction. Compared with the static reconstruction, only one instead of 3 holes have to be drilled and only 1 interference screw has to be placed, thus shortening the surgery time. From a theoretical biomechanical perspective, the dynamic tensioning is superior to the static procedure. The few accomplished studies published so far by Becher et al and Ostermeier et al show good or better functional results (Kujala, Lysholm, Tegner scores) with the dynamic MPFL reconstruction, yet higher evidence studies need to be performed. Conclusion: Dynamic MPFL reconstruction appears to be a simpler and more effective surgical technique for MPFL reconstruction. Because of its novelty, high evidence studies assessing long-term therapeutical outcomes are still lacking and need to be conducted in order to compare it conclusively with the static procedure.

A Higher Initial Tensioning Force of an ACL Graft Results in a Higher Graft Force After Screw Fixation Irrespective of the Screw Diameter: A Biomechanical Study

Background: The intra-articular graft force (IAGF) in anterior cruciate ligament reconstruction decreases quickly over the first hours after surgery. Nevertheless, little is known about whether the initial extra-articular tensioning force (EATF) and screw diameter affect the graft force after fixation. Purpose: To investigate the effects of different EATFs on the IAGF of a soft tissue graft fixated via a bioabsorbable interference screw over 100 minutes after fixation and to evaluate the effects of different screw diameters within 1 mm of the tunnel width during this process. Study Design: Controlled laboratory study. Methods: In this biomechanical study, a porcine quadruple-strand soft tissue graft was inserted into the tibial anterior cruciate ligament tunnel. On the extra-articular side, 3 loads were applied during retrograde insertion of the bioabsorbable interference screw (6, 7, and 8 mm): 20 N, 80 N, and maximum manual EATF (Nmax). Nine study groups consisting of 10 tibiae each were created to test the effects of different EATFs and screw sizes. The IAGF was measured up to 100 minutes after the EATF was released. Results: An EATF ≥80 N resulted in a larger IAGF for all screw sizes at 100 minutes. There were no significant associations between the IAGF at 100 minutes and different screw diameters. Inserting the tibial screw significantly increased the IAGF in all groups, with the exception of Nmax applied in groups with 7- or 8-mm screws. When compared with the end of screw insertion, after the release of the EATF, the IAGF dropped by 55% to 77 % at 100 minutes. Conclusion: An initial EATF ≥80 N is associated with a significantly larger IAGF at 100 minutes in this cadaveric simulation. The IAGF in soft tissue grafts decreased substantially after the retrograde placement of an interference screw. A recommendation regarding screw diameter with respect to the IAGF cannot be given. Clinical Relevance: To obtain a higher residual graft force after bioabsorbable interference screw fixation, an initial EATF ≥80 N should be applied according to this model. The significant decrease in graft force after the release of the EATF indicates that the reconstructed knee cannot be mechanically stabilized after the surgery.

Strength of interference screw fixation of meniscus prosthesis matches native meniscus attachments

Purpose Meniscal surgery is one of the most common orthopaedic surgical interventions. Total meniscus replacements have been proposed as a solution for patients with irreparable meniscal injuries. Reliable fixation is crucial for the success and functionality of such implants. The aim of this study was to characterise an interference screw fixation system developed for a novel fibre-matrix-reinforced synthetic total meniscus replacement in an ovine cadaveric model. Methods Textile straps were tested in tension to failure (n = 15) and in cyclic tension (70–220 N) for 1000 cycles (n = 5). The textile strap-interference screw fixation system was tested in 4.5 mm-diameter single anterior and double posterior tunnels in North of England Mule ovine tibias aged > 2 years using titanium alloy (Ti6Al4Va) and polyether-ether-ketone (PEEK) screws (n ≥ 5). Straps were preconditioned, dynamically loaded for 1000 cycles in tension (70–220 N), the fixation slippage under cyclic loading was measured, and then pulled to failure. Results Strap stiffness was at least 12 times that recorded for human meniscal roots. Strap creep strain at the maximum load (220 N) was 0.005 following 1000 cycles. For all tunnels, pull-out failure resulted from textile strap slippage or bone fracture rather than strap rupture, which demonstrated that the textile strap was comparatively stronger than the interference screw fixation system. Pull-out load (anterior 544 ± 119 N; posterior 889 ± 157 N) was comparable to human meniscal root strength. Fixation slippage was within the acceptable range for anterior cruciate ligament graft reconstruction (anterior 1.9 ± 0.7 mm; posterior 1.9 ± 0.5 mm). Conclusion These findings show that the textile attachment-interference screw fixation system provides reliable fixation for a novel ovine meniscus implant, supporting progression to in vivo testing. This research provides a baseline for future development of novel human meniscus replacements, in relation to attachment design and fixation methods. The data suggest that surgical techniques familiar from ligament reconstruction may be used for the fixation of clinical meniscal prostheses.

Update On Performance And Return To Sport After Biceps Tenodesis In Professional Baseball Players (226)

Objectives: Determine the return to sport (RTS) rate and performance upon RTS in professional baseball players who underwent biceps tenodesis. Methods: All professional baseball pitchers who underwent biceps tenodesis between 2014 and 2017 were included. Players with concomitant rotator cuff repair were excluded. Demographic and performance data (preoperative and postoperative) were recorded for each player. Performance metrics were then compared between the biceps tenodesis and matched control (no history of biceps tenodeses) groups. Results: 14 players (average age 27±4 years; 12 pitchers, 2 position outfielders) were included. Most (79%) were open subpectoral tenodeses while one was an arthroscopic biceps transfer and one was arthroscopic suprapectoral. Fixation methods included cortical button (42%), interference screw (25%), suture anchor (25%) and drill holes (8%). Most players (79%) underwent concomitant procedures (43% underwent SLAP repair). Among the 14 players, 2 were unable to RTS, 5 RTS but to a lower level, and 7 RTS at the same or a higher level. Thus, overall, while 86% (12/14) were able to RTS, 50% (7/14) were able to return to the same or a better level and 50% were either unable to return or returned to a lower level. Among pitchers specifically, 100% (12/12) were able to return to play, but only 50% (6/12) were able to return to the same or a higher level. For those players who did return to play, it took 245±84 days, their performance was unchanged and did not differ from matched controls. Conclusions: While 86% of professional baseball players returned to sport following biceps tenodesis, only 50% returned at the same or higher level. No decline in performance was noted in players who successfully returned. Open subpectoral tenodesis is the most common tenodesis technique performed on professional baseball players.