Thermal effects after anterior cruciate ligament shrinkage using radiofrequency technology: a porcine cadaver study

Biomechanical Performance of Hip Labral Repair Techniques

PURPOSE

To determine the strength of various suture techniques and the impact of suture passer size on cyclically loaded hip labra.

METHODS

We assigned 63 bovine hip labra to 9 simple knotless suture technique groups using OrthoCord suture: (1) penetrating grasper (2.6 mm)-placed horizontal mattress, (2) penetrating grasper-placed vertical mattress, (3) SutureLasso (1.8 mm)-placed vertical mattress, (4) penetrating grasper-placed oblique repair, (5) penetrating grasper-placed vertical mattress plus radiofrequency, (6) SutureLasso-placed horizontal mattress, (7) SutureLasso-placed oblique mattress, (8) SutureLasso-placed horizontal mattress plus radiofrequency, and (9) SutureLasso-placed oblique mattress plus radiofrequency. After 20 cycles of uniaxial tensile loading (5 to 80 N), destructive testing was performed.

RESULTS

Penetrating grasper-placed horizontal mattress sutures showed lower ultimate failure loads than vertical and oblique mattress sutures (P < .05). Penetrating grasper-placed vertical mattress sutures had higher peak-to-peak displacement than SutureLasso-placed vertical mattress sutures (P = .04). SutureLasso-placed oblique mattress sutures had a higher ultimate load (P < .01) and stiffness (P = .04) than SutureLasso-placed horizontal mattress sutures. SutureLasso-placed horizontal mattress sutures had lower cyclic elongation than penetrating grasper-placed horizontal mattress sutures (P = .01) and lower ultimate load (P < .01) and stiffness than SutureLasso-placed vertical mattress sutures (P < .01). Horizontal mattress sutures with radiofrequency had a higher ultimate load (P = .02), stiffness, and cyclic elongation (P < .01) than without radiofrequency.

CONCLUSIONS

A horizontal mattress hip labrum stitch shows a lower ultimate failure load than vertical or oblique mattress stitches. Smaller-diameter suture-passing devices show less cyclic displacement and elongation than larger-diameter devices. Radiofrequency labral treatment does not alter vertical stitch strength but does alter horizontal mattress stitch strength.

CLINICAL RELEVANCE

Vertical and oblique stitches are stronger than horizontal stitches. A 1.8-mm passing device shows a better cyclic loading performance than a 2.6-mm device.

Short-term effects of radiofrequency shrinkage treatment for anterior cruciate ligament relaxation on proprioception

OBJECTIVE

Radiofrequency (RF) shrinkage is used in anterior cruciate ligament (ACL) reconstruction. The present study investigated the therapeutic effects of RF on ACL relaxation and the probable influencing factors.

METHODS

Patients with ACL relaxation were included. Participants were randomly divided into two groups: a treatment group, in which patients were treated with RF shrinkage (RF group); a control group, in which patients received conventional surgical treatment. Thermal shrinkage was performed on ACL using an ArthroCare® CAPSure® wand. Lysholm scores, proprioceptive testing and Tegner activity scores were evaluated before and after treatment (at 6 and 12 months).

RESULTS

A total of 38 patients were included. The mean ± SD Lysholm score of those in the RF group at 12 months' post-treatment was significantly higher than in controls. The angle of deviation of the knee joint in RF group was significantly larger than in the control group at 6 months' post-treatment.

CONCLUSIONS

RF shrinkage treatment for ACL laxity could improve knee scores, and may affect proprioception and recovery of activity after surgery.

In vivo effects of partial electrothermal shrinkage on mechanical properties of the anterior cruciate ligament in rabbits

BACKGROUND

No studies have been conducted to clarify an in vivo remodeling of the radiofrequency-treated lesion of the anterior cruciate ligament. The purpose was to determine in vivo effects of radiofrequency shrinkage on mechanical properties of the anterior cruciate ligament.

METHODS

Thirty skeletally mature rabbits were used. In each group, radiofrequency energy set at non-ablative levels was applied to the posterolateral bundle of the anterior cruciate ligament with a bipolar radiofrequency generator. All animals were sacrificed at 0, 6, and 12 weeks after surgery, respectively. In each group, 7 and 3 out of the 10 specimens were used for biomechanical and histological evaluations.

FINDINGS

After shrinkage treatment, the anterior-posterior translation of the knee and the length of the posterolateral bundle were significantly reduced immediately after surgery, but that this effect disappeared at 6 weeks. The tensile strength and the tangent modulus of the treated bundle were significantly lower than that of the normal control bundle at each period. In addition, the tensile strength and the tangent modulus measured at 12 weeks were significantly lower than that at 0 week. Histological examination showed granulation-like tissues with numerous plump fibroblasts and inflammatory cells were dominantly found in the midsubstance of the posterolateral bundle at 12 weeks.

INTERPRETATIONS

This result suggested that the anterior cruciate ligament tissue shortened with the radiofrequency treatment is elongated gradually over time. The mechanical properties of the posterolateral bundle of the anterior cruciate ligament reduced by the radiofrequency shrinkage are not restored in vivo, but significantly deteriorated with time.