Biomechanics of a novel technique for suprapectoral intraosseous biceps tenodesis.

BACKGROUND: The Caspari-Weber (C.W.) tenodesis is a standard miniopen intraosseous technique to fix the long head of the biceps tendon. The suprapectoral intraosseous biceps tenodesis (SPIBiT) is a novel arthroscopic, intraosseous, tendon-sparing alternative using a cortical button. No biomechanical data exist comparing the time-zero performance of the SPIBiT and C.W. constructs. METHODS: Nine pairs of human cadaver shoulders were tested. The SPIBiT used a finger-trap suture pattern holding the tendon inside a humeral tunnel above the pectoralis tendon, anchored with a cortical button on the anterior humerus distal to the bicipital groove. The subpectoral C.W. used a Krackow suture technique. Specimens underwent 500 cycles of uniaxial loading, followed by ultimate failure testing. RESULTS: The SPIBiT was placed in 5 left and 4 right humeri (5 female, 4 male; 59 ± 6 years). The C.W. was initially stiffer (P = .003), whereas the SPIBiT exhibited higher energy dissipation (hysteresis; P = .006). Metrics decreased for both constructs over 500 cycles (P ≤ .050). Constructs failed through suture bunching and tendon tearing within the main suture bundle. The SPIBiT exhibited a novel failure in 2 specimens, with the cortical button pulling distally and suture cutting through cortical bone. Failure occurred at 272.0 ± 114.3 N and 282.3 ± 59.4 N for the SPIBiT and C.W., respectively (P = .766). The C.W. was stiffer (P < .001). CONCLUSION: The SPIBiT is an arthroscopic suprapectoral intraosseous alternative to the C.W. biceps tenodesis, but in light of the novel failure mode, clinical use is not recommended. Future investigations should quantify the impact of construct compliance on healing, and future constructs should avoid suture point loading on thin cortical bone.

Biomechanical comparison of two techniques for arthroscopic suprapectoral biceps tenodesis: interference screw versus implant-free intraosseous tendon fixation.

BACKGROUND: A novel arthroscopic technique allows for intraosseous tendon placement in biceps tenodesis using bone tunnels and suture while avoiding the expense of an implant. No biomechanical characterization exists for this construct. METHODS: Tensile tests were used to compare a suture-only biceps tenodesis technique (arthroscopic biceps intraosseous tenodesis [ABIT]) with interference screws in 7 pairs of cadaveric shoulders. The ABIT used a modified finger-trap suture method to secure the tendon to itself through an intraosseous bone tunnel. Interference screw placement followed the manufacturer's protocol for implantation. An open technique was used to provide consistency during laboratory preparation. RESULTS: During cyclic loading, the screws were significantly stiffer (P = .040) but dissipated more energy (P = .002). During failure loading, suture-only specimens showed significantly greater failure loads (P < .001) and deformation (P = .046). The failure mechanism for the ABIT method was tendon elongation with progressive tensioning and slippage of the tendon through the suture mass. No complete tendon failure occurred for the ABIT. Gross tendon failure occurred in all interference screw tests at the bone-tendon-screw interface. No screw or suture failed in any biceps tendon test. CONCLUSION: The ABIT construct showed significantly higher failure loads and deformation compared with interference screws. The comparable stiffness after cycling of both constructs suggests that micromotion at the bone-tendon interface is similar, which-in addition to the intraosseous fixation-may be important in promoting healing. The ABIT construct was found to absorb and restore more energy (hysteresis), suggesting potential for greater tendon preservation, which may translate into improved construct longevity. The suture-only method can eliminate the expense of an implant.

Biomechanical performance of traditional arthroscopic knots versus slippage-proof knots.

PURPOSE: To compare the biomechanical, time, and profile characteristics of a new sliding locking knot termed the slippage-proof knot (SPK) and a modified slippage-proof knot (MSPK) with those of traditional arthroscopic knots. METHODS: We evaluated the Samsung Medical Center (SMC) knot, Revo knot, SPK, and MSPK (an SPK with a single added half-hitch) tied with high-strength suture, with 11 trials of each cycled 1,000 times between 10 and 45 N and then loaded to failure. Total displacement during cyclical testing, maximal load to failure, and mode of failure were recorded for each knot. We also measured the dimensions of the knots and the time required to tie each knot. RESULTS: On load-to-failure testing, no difference in strength was found between the SMC and Revo knots (P = .082). The Revo knot and MSPK were also of equivalent strength (P = .183), and the SMC knot was 11% stronger than the MSPK (P = .017). All 3 of these knots were stronger than the SPK. On cyclical testing, the SMC knot, Revo knot, and MSPK allowed equivalent total displacement and allowed statistically less total displacement than the SPK. All SMC knots, Revo knots, and MSPKs failed by suture breakage, whereas the SPKs all slipped at failure. We found that the SPKs and MSPKs are tied more quickly than traditional knots. The SPK and MSPK dimensions are wider yet shorter than those of the other knots in the study. CONCLUSIONS: Our results indicate that the MSPK has biomechanical properties comparable to the SMC and Revo knots despite only requiring 1 added half-hitch, whereas the SPK was found to be significantly inferior to the other knots tested. We found that the slippage-proof knots (SPK and MSPK) were tied more quickly and have shorter, wider profiles than traditional knots. CLINICAL RELEVANCE: The MSPK has knot security comparable to the SMC and Revo knots while requiring only 1 added half-hitch, and it may be most beneficial in cases in which a large number of knots will be tied because the fewer required half-hitches reduces the surgical time without reducing its biomechanical properties.

Medial patellofemoral ligament reconstruction using a modified "reverse-loop" technique.

Medial patellofemoral ligament reconstruction is a commonly performed procedure for patellofemoral instability. In recent years the surgery has evolved considerably as the anatomy and goals of reconstruction have become more defined. This has resulted in numerous surgical options involving various fixation devices. Furthermore, as biomechanical data accumulate regarding the importance of graft position and tension, surgical techniques for applying this knowledge with precision are needed. This technical note with an accompanying video details one such technique that may be applied to various methods of fixation, allowing for improved precision and possibly resulting in a stronger fixation construct.