Anne M. Kelly

The use of the contact Nd:YAG laser in arthroscopic surgery: Effects on articular cartilage and meniscal tissue

The contact Nd:YAG lasers small size, tip variety, fiberoptic application, and suitability for use in a saline medium make it a particularly appealing tool for use in arthroscopic procedures. This study was performed to investigate the lasers effects on articular cartilage and meniscal tissue with respect to depth of damage (canine cadaver model) and healing response (rabbit model). Depth of damage in the canine cadaver model was greater in meniscal tissue than in articular cartilage at each wattage level. In the presence of a saline bath, depth damage in both tissues was diminished. Scalpel articular cartilage lesions showed no response over time. Electrocautery lesions uniformly showed significant wide margins of hyaline cartilage necrosis which increased over time. Laser articular cartilage lesions showed vigorous healing responses characterized by fibrocartilage healing by 6 weeks. Scalpel meniscectomies showed characteristic fibrocartilagenous remodeling by 6 weeks, while electrocautery meniscectomies showed wide margins of necrosis with no specimen showing remodeling capability. Laser meniscectomies showed an intermediate response with a small number of menisci remodeling in a normal fashion. This article represents the first comprehensive look at the effects of the Nd:YAG laser on articular cartilage and meniscal tissue in terms of depth of damage and healing response over time, and indicates this lasers biological advantage over scalpel and electrocautery in arthroscopic procedures.

Suture Number Determines Strength of Rotator Cuff Repair

BACKGROUND Failure of surgical repair of a rotator cuff tear continues to be a clinical problem. For other tendon repairs, increasing the number of sutures improves both biomechanical performance and clinical outcomes. Several investigators have shown biomechanical advantages of double-row techniques but have used many more sutures than were used with the single-row techniques with which the double-row techniques were compared. The purposes of our study were to establish whether using a greater number of sutures would improve the biomechanical properties of a rotator cuff repair model, and whether using equal numbers of sutures would lead to equivalent results between single and double-row configurations. METHODS Fresh-frozen sheep infraspinatus tendons underwent single-row repair with two, four, or six mattress sutures and double-row repair with use of four mattress sutures. Specimens were pretensioned at 10 N for one minute, then cycled from 10 to 180 N for 200 cycles at 0.2 Hz; this was followed by load to failure. Cyclic gap formation, failure load, and failure type were recorded. RESULTS The four-suture single-row and four-suture double-row repairs had similar gap formation during cyclic testing, with no significant differences between them. Cyclic gap formation in the two-suture single-row group was 6.7 and 7.1 mm (97% and 109%) greater than that in the four and six-suture single-row groups after 200 cycles (p < 0.001). The average loads to failure of the two, four, and six-suture single-row groups were 274, 362, and 572 N (p < 0.0001). The average load to failure of the four-suture double-row group was 386 N, which was similar to the value in the four-suture single-row group (p = 0.58). CONCLUSIONS In an ovine rotator cuff tendon repair model, increasing the number of sutures decreased cyclic gap formation and increased load to failure. Single and double-row repairs are biomechanically equivalent when the number of sutures is kept constant. CLINICAL RELEVANCE The results of this study support the use of greater numbers of sutures in rotator cuff repair and disagree with the assertion that double-row repairs are biomechanically superior to single-row repairs.

Subscapularis tendon loading during activities of daily living

BACKGROUND The purpose of this study was to determine the relative amount of load that is transmitted through the superior portion of the subscapularis during activities of daily living as compared with the load that is transmitted through the middle and inferior portions in a normal shoulder and in a shoulder with a supraspinatus tear. METHODS By use of the Newcastle shoulder model, the subscapularis was modeled with 3 lines of action encircling the humeral head. The load was measured in the entire subscapularis, and the percentage of this load in each of the 3 tendinous bands was calculated. Subsequently, a supraspinatus tear was simulated, and the forces generated by the subscapularis and glenohumeral joint contact forces were measured. RESULTS The maximum force produced by the entire subscapularis muscle for the various activities ranged from 3 to 43 N. Load sharing between the 3 subscapularis bands showed that the superior band bore the largest percentage of the total load of the muscle (95% ± 2%). The load in the subscapularis, particularly in the superior band, increased significantly when a supraspinatus tear was simulated (P < .0001). CONCLUSION The superior band of the subscapularis tendon bears the highest percentage of load compared with the middle or inferior band. The load in the subscapularis increased significantly in the presence of a simulated supraspinatus tear. Because a disproportionate amount of force is transmitted through the superior subscapularis, more clinical research is warranted to determine whether tears in this region should be routinely repaired.

How Variable Are Achilles Allografts Used for Anterior Cruciate Ligament Reconstruction? A Biomechanical Study:

Background: Allograft tendon used in anterior cruciate ligament reconstruction (ACLR) requires sterilization before implantation. Low-dose gamma irradiation is a means of sterilization that may minimize tissue damage. Purpose: To quantify the variability in mechanical properties between low-dose irradiated Achilles tendon allografts used for ACLR. Study Design: Descriptive laboratory study. Methods: A total of 15 intact outer-third Achilles tendon allograft specimens were collected from the remains of full Achilles allografts used for intraoperative ACLR at a single hospital. All grafts were obtained from a single tissue bank and underwent proprietary disinfection and low-dose gamma irradiation (1.5-2.5 Mrad). Biomechanical testing was carried out to measure tendon elongation, failure location during tensile testing, maximum stress, maximum strain, and modulus of elasticity. The mean and standard deviation were calculated for each outcome measure, and the variability between specimens was calculated by the coefficient of variation (CV). The effect of donor age on graft material properties was examined by use of linear regression. One-way analysis of variance was performed to compare differences in the mechanical properties across failure locations. Results: During cyclic testing, tendon elongation averaged 1.4% ± 1.6% with a CV of 118%. During failure testing, the maximum stress averaged 12.2 ± 4.1 MPa, maximum strain averaged 21.0% ± 6.3%, and modulus of elasticity averaged 95.5 ± 30.8 MPa. The CVs for maximum stress, maximum strain, and modulus of elasticity were 34%, 30%, and 32%, respectively. Ten tendons failed in the midsubstance and 5 failed at the tendon-bone enthesis. No differences were noted in mechanical properties between grafts that failed in the midsubstance versus those that failed at the enthesis. Donor age did not correlate with allograft elongation during cyclic load or any of the material property measures during failure testing. Conclusion: The variabilities in the material properties and graft elongation during cyclic loading of Achilles tendon allografts used in ACLR fall within the range of properties reported in the literature for other ACLR allografts. Material properties do not differ by donor age or graft failure location observed during failure testing. Clinical Relevance: Surgeons should be aware that there exists considerable variation in the mechanical properties of Achilles allograft tendons used for ACLR. This variability is difficult to detect by tissue bank screening or the treating surgeon’s inspection and may contribute to the heterogeneity in outcomes of allograft ACLR.

Paper #107 Arthroscopic release of the long head of the biceps tendon: functional outcome and clinical results

found no significant increase in bicepsbrachii activity during isolated shoulder motion when thepatient’s elbow motion was controlled with a brace. Theyconcluded that the LHBT does not play a significant rolein either the rotator cuff–deficient or normal shoulder.Levy et al supported this finding in an EMG analysis ofthe LHBT in 10 shoulders, in which shoulder motion wasisolated by using a long arm brace to lock the elbow inextension and the forearm in the neutral position.

Arthroscopic contact Nd:YAG laser meniscectomy: surgical technique and clinical follow-up

Fifteen patients were studied prospectively as a pilot study to evaluate the safety and efficacy of the contact Neodynium: Yttrium Aluminum Garnet (Nd:YAG) laser in performing arthroscopic meniscal resection in a saline medium, (Surgical Laser Technologies; Malverne, PA). All fifteen patients were rated as having clinically excellent results based on pain relief, wound healing, and post-operative swelling. Although there was increased time involved with setting up and calibrating the laser, there was not an increase in time for meniscal resection. In addition, the decreased need for secondary trimming and increased accessibility to the posterior horns of the menisci represent advantages over conventional instruments. Based on the findings, arthroscopic contact Nd:YAG laser surgery is a safe and effective clinical tool for meniscal resection which may, with increased technological advancements and cost reduction, replace standard instrumentation.