Thermal capsular shrinkage for shoulder instability

Impact of Collagen Crosslinking on Dislocated Human Shoulder Capsules-Effect on Structural and Mechanical Properties

Classical treatments of shoulder instability are associated with recurrence. To determine whether the modification of the capsule properties may be an alternative procedure, the effect of crosslinking treatment on the structure and mechanical properties of diseased human shoulder capsules was investigated. Joint capsules harvested from patients during shoulder surgery (n = 5) were treated or not with UV and/or riboflavin (0.1%, 1.0% and 2.5%). The structure and the mechanical properties of the capsules were determined by atomic force microscopy. The effect of treatments on cell death was investigated. Collagen fibrils were well-aligned and adjacent to each other with a D-periodicity of 66.9 ± 3.2 nm and a diameter of 71.8 ± 15.4 nm in control untreated capsules. No effect of treatments was observed on the organization of the collagen fibrils nor on their intrinsic characteristics, including D-periodicity or their mean diameter. The treatments also did not induce cell death. In contrast, UV + 2.5% riboflavin induced capsule stiffness, as revealed by the increased Young's modulus values (p < 0.0001 for each patient). Our results showed that the crosslinking procedure changed the biomechanics of diseased capsules, while keeping their structural organisation unchanged at the single fibril level. The UV/riboflavin crosslinking procedure may be a promising way to preserve the functions of collagen-based tissues and tune their elasticity for clinically relevant treatments.

Online resources for shoulder instability: what are patients reading?

BACKGROUND

Evaluations of the medical literature suggest that many online sites provide poor-quality information. The purpose of our study was to investigate the value of online resources for patient education about shoulder instability.

METHODS

Three search terms ("shoulder instability," "loose shoulder," and "shoulder dislocation") were entered into three Internet search engines. Three orthopaedic residents independently gauged the quality and accuracy of the information with use of a set of predetermined scoring criteria, in addition to noting whether or not four potential surgery options were mentioned. The readability of the web sites was evaluated with use of the Flesch-Kincaid score.

RESULTS

Eighty-two unique web sites were evaluated. Quality and accuracy were significantly higher with use of the term "shoulder instability" compared with the term "loose shoulder" (quality, p < 0.001; accuracy, p = 0.001). However, the reading level was significantly more advanced for the "shoulder instability" web sites (p < 0.001). Quality was significantly higher on web sites with reading levels above the eighth grade level (p = 0.001) (88% of web sites). Only twenty-three sites (28%) mentioned surgical options for shoulder instability, and of these, only eight mentioned thermal capsulorrhaphy as a primary treatment.

CONCLUSIONS

Online information regarding shoulder instability is often inaccurate and/or at an inappropriately high reading level. The quality of information is highly dependent on the specific search term used. Clinicians need to be aware of the information that is available online and should help direct patients to proper sites and guide Internet search terms.

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.

The effect of electrothermal shrinkage on the biomechanical properties of the anterior cruciate ligament: an experimental study

PURPOSE

The purpose of this study was to determine the acute effects of electrothermal shrinkage on the biomechanical properties of the anterior cruciate ligament (ACL).

TYPE OF STUDY

Randomized trial.

METHODS

Fifty fresh femur-ACL-tibia complexes harvested from fully matured pigs were used. The femur-anteromedial bundle-tibia complex specimens were randomly divided into 5 groups of 10 specimens each. In each group, radiofrequency energy set at nonablative levels was applied to the anteromedial bundle of the ACL with a bipolar radiofrequency generator. In groups I and II, radiofrequency treatment was applied to the ACL using 28 W and 45 W power, respectively, for 30 seconds. In groups III and IV, radiofrequency treatment was applied to the ACL using 28 W and 45 W power, respectively, for 60 seconds. In group V, no treatment was applied in order to obtain normal control data. The treatment was performed in physiological saline solution under a 1-N load. In each group, 8 of the 10 specimens were used for biomechanical evaluation, and the remaining 2 were used for histologic observation.

RESULTS

Concerning the length of the anteromedial bundle after the treatment, the analysis of variance (ANOVA) showed a significant difference among the 5 groups. The length in groups I, II, III, and IV was significantly shorter than that of group V. In tensile testing, the stiffness was 120, 116, 113, 89, and 156 N/mm in groups I, II, III, IV, and V, respectively. The ANOVA showed a significant difference among the groups. Groups I, II, III, and IV were significantly lower than group V, respectively. Histologic examination showed diffuse collagenous denaturation and pyknotic nuclear changes in fibroblasts at the treated portion. The collagen crimp pattern was not present in the treated area.

CONCLUSIONS

Application of RF energy to the specimens caused both shortening and weakening according to the magnitude and duration of the application.

CLINICAL RELEVANCE

These results may explain one of the causes of the poor results reported in some clinical studies. This study warns against a too optimistic application of electrothermal shrinkage to the ACL as a clinical treatment.

A salvage procedure for refractory shoulder instability

We present the case of a patient with symptomatic refractory multidirectional shoulder instability who was treated with staged bilateral anterior and posterior glenoid bone augmentation after previous failed arthroscopic and open procedures. The patient was pain free postoperatively and has not had symptoms of instability in either shoulder. At her most recent followup, 24 months after surgery, she had nearly full symmetric shoulder range of motion without anterior or posterior apprehension signs. Her Constant-Murley scores were 77 and 79 on the right and left, respectively, with UCLA scores of 29 on the right and the left shoulders. Her Short Form-36 overall score was 105, indicating overall satisfaction. Currently, the patient states that she can do all daily activities without restrictions. In carefully selected patients, the use of anterior and posterior glenoid bone augmentation may be effective as a salvage procedure in rare cases of refractory multidirectional shoulder instability.

Thermal capsulorrhaphy

The initial wave of enthusiasm for thermal capsulorrhaphy has subsided. Long-term clinical data were lacking until D'Alessandro et al's prospective study indicated the results were not as promising as the previously reported short-term studies. Complications including obliteration or attenuation of capsular tissue, axillary nerve injury, and chondrolysis have all been reported in recent years further raising concern about the widespread use of this procedure. The inexact nature of how much "shrinkage" is being performed has led surgeons to further develop surgical technique in capsular plication, shift, or advancement. Although it remains to be seen if these techniques will lead to good clinical outcomes, it appears that they more closely resemble the original operative procedure-anterior capsular shift.