A Superolaterally Placed Anchor for Subscapularis "Leading-Edge" Refixation: A Biomechanical Study.

PURPOSE: To compare a conventional single-row (SR) repair technique and 2 double-row (DR) repair techniques to restore and protect the superolateral aspect of the subscapularis (SSC) tendon and ensure SSC leading-edge reconstruction in a cadaveric model. METHODS: The native footprint was measured in 15 pairs of human cadaveric shoulders (N = 30) with a mean age of 67.2 years. According to the Fox-Romeo classification, a 25% defect or 50% defect in a superior-inferior direction was created. Specimens were mounted onto a servohydraulic test system to analyze contact variables at 0° and 20° of abduction with a force-controlled ramped program up to 50 N. In addition, each specimen was cyclically loaded (10-100 N, 300 cycles). The tears were repaired with 1 of 3 constructs: a 2-anchor medially based conventional SR construct, a 2-anchor-based hybrid DR construct, or a 3-anchor-based DR construct. The outcome variables were ultimate tensile load, displacement, and pressurized footprint coverage. RESULTS: All reconstructions resulted in stable constructs with peak loads exceeding 450 N (P = .68). The overall displacement during cyclic loading was between 1.2 and 3.0 mm (P = .70). A significant difference was seen when the 2 arm positions of 0° and 20° of abduction were compared, showing a constant reduction of pressurized footprint coverage with the arm abducted (P = .01). Analyzing footprint coverage with respect to the region of interest-the leading edge of the SSC-we observed a significant difference between the SR construct and a construct using a superolaterally placed anchor (25% defect, P = .01; 50% defect, P = .01), whereas no statistical differences were detectable between the hybrid DR construct and the DR construct. CONCLUSIONS: The leading edge of the SSC tendon can best be restored by using a superolateral anchor, whereas no statistical difference in load to failure in comparison with an SR construct or with the addition of a third anchor was detectable. CLINICAL RELEVANCE: The SSC is critical for proper shoulder function. Without an increase in the number of implants, a significantly better footprint reconstruction can be achieved by placing an anchor superior and lateral to the native footprint area close to the entrance of the bicipital groove.

Footprint coverage comparison between knotted and knotless techniques in a single-row rotator cuff repair: biomechanical analysis.

BACKGROUND: The objective of this biomechanical study is to compare two variations of single-row knotless techniques (Knotless repair and Rip-stop Knotless repair) against a single-row double-loaded anchor (DL) repair, focused on evaluating contact pressure and contact area amongst three different single-row techniques for rotator cuff repairs. METHODS: A total of 24 fresh frozen human shoulders were tested. Specimens were randomly assigned into one of the three single-row (SR) repair groups: A Knotted single-row double-loaded anchor (DL) repair, a Knotless (K) repair, or a Knotless Rip-Stop (KRS) repair. The footprint was measured after complete detachment of the supraspinatus tendon from the greater tuberosity, introducing pressure sensors between bony footprint and detached rotator cuff, and finally reconstructing it. All specimens were mounted onto a servohydraulic test system to analyze contact variables at 0° and 30° of abduction with 0 N, 30 N and 50 N of tension. RESULTS: Groups did not differ significantly in their footprint sizes: DL group 359.75 ± 58.37 mm2, K group 386.5 ± 102.13 mm2, KRS group 415.87 ± 93.80 mm2 (p = 0.84); nor in bone mineral density: DL group 0.25 ± 0.14 g/cm2, K group 0.32 ± 0.19 g/cm2, KRS group 0.32 ± 0.13 g/cm2, (p = 0.75) or average age. The highest mean pressurized contact area measured for the K repair was 248.1 ± 50.9 mm2, which equals a reconstruction of 67.1 ± 19.3% at 0° abduction and a 50 N supraspinatus load. This reconstructed area was significantly greater compared with the DL repair 152.8 ± 73.1 mm2, reconstructing 42.0 ± 18.5% on average when under the same conditions (p = 0.04). The mean contact pressure did not significantly differ amongst groups (p = 1.0): DL group 30.8 ± 17.4 psi, K group 30.9 ± 17.4 psi and KRS group 30.0 ± 10.9 psi. Neither the 30° abduction angle nor the supraspinatus load had a significant influence on the contact pressure in our study. CONCLUSION: Both single-row knotless techniques resulted in significantly higher footprint reconstruction, providing larger contact area and a more uniform pressure distribution when compared with the single-row Knotted techniques. The mean contact pressure did not differ among groups significantly. These knotless techniques may be an alternative if the surgeon decides to perform a single-row rotator cuff repair. LEVEL OF EVIDENCE: Basic Science Study, Biomechanics.

Protective Nature of Platelet-Rich Plasma Against Chondrocyte Death When Combined With Corticosteroids or Local Anesthetics.

BACKGROUND: The use of corticosteroids and local anesthetics to treat osteoarthritis has established benefits, including relief of pain and increased range of motion, but may also have the potential to lead to tissue atrophy or degeneration, specifically on chondrocytes. There is growing evidence that platelet-rich plasma (PRP) has anti-inflammatory characteristics that can limit the cytotoxic effects of corticosteroids and local anesthetics. Hypothesis/Purpose: The purpose of this study was to determine the effects of PRP in chondrocyte cultures when combined with corticosteroids or local anesthetics. The hypothesis of this study was that PRP would (1) dampen the negative effects on chondrocyte viability and (2) improve chondrocyte proliferation seen with corticosteroid or local anesthetic treatment alone. STUDY DESIGN: Controlled laboratory study. METHODS: Peripheral blood was obtained from 8 healthy participants, followed by centrifugation to obtain PRP. Human chondrocytes were treated with PRP alone or in combination with corticosteroids or local anesthetics. Saline (concentration of 0.9%) served as the control. Luminescence and radioactive thymidine assays were performed to examine chondrocyte viability and proliferation, respectively. Cell exposures of 0, 5, 10, and 30 minutes were used for viability and 120 hours for proliferation. RESULTS: The presence of PRP significantly limited the negative effect on chondrocyte viability at tested time points for the examined corticosteroids and local anesthetics ( P < .05). PRP in addition to corticosteroids and local anesthetics significantly improved chondrocyte proliferation ( P < .05). CONCLUSION: The addition of PRP can significantly reduce the cytotoxic effects of corticosteroids and/or local anesthetics applied to chondrocytes. PRP can improve the proliferation of chondrocytes compared with corticosteroids or local anesthetics alone. CLINICAL RELEVANCE: With the use of corticosteroids and local anesthetics for temporary symptomatic relief and improvement of function to treat the chronic progressive nature of osteoarthritis, long-term negative effects of these agents can be limited with the parallel use of PRP.

The enthesis: a review of the tendon-to-bone insertion.

The integration of tendon into bone occurs at a specialized interface known as the enthesis. The fibrous tendon to bone enthesis is established through a structurally continuous gradient from uncalcified tendon to calcified bone. The enthesis exhibits gradients in tissue organization classified into four distinct zones with varying cellular compositions, mechanical properties, and functions in order to facilitate joint movement. Damage to tendinous insertions is common in the field of orthopaedic medicine and often involves surgical intervention that requires the attempted recreation of the natural organization of tendon into bone. The difficulty associated with recreating the distinct organization may account for the surgical challenges associated with reconstruction of damaged insertion sites. These procedures are often associated with high failure rates and consequently require revision procedures. Management of tendinous injuries and reconstruction of the insertion site is becoming a popular topic in the field of orthopaedic medicine.