SHOULDER INSTABILITY: THERMAL TREATMENT

Shoulder Instability

Thermal Treatment

Donald F. D’Alessandro

Athletes and laborers often present to the orthopedist with shoulder complaints resulting from instability. Glenohumeral instability is a challenging clinical problem including a spectrum of diagnoses and a variety of treatment options. In the last decade, arthroscopic stabilization techniques have been proposed as an alternative to the traditional open reconstruction procedures. Unfortunately, long-term follow-up of these earlier techniques has yielded unacceptably high recurrence rates (averaging 20%). Although the Bankart lesions are effectively repaired arthroscopically, these failures may be attributed to inadequate management of the associated capsular laxity. Thermal shrinkage is an important addition to our armamentarium for addressing pathologic capsular redundancy arthroscopically. Thermal capsulorrhaphy may be used alone or in conjunction with other arthroscopic stabilization techniques in an effort to achieve success rates comparable to open procedures.

Pathophysiology of Shoulder Instability

Shoulder instability represents a spectrum of clinical entities. Successful treatment is predicated on a clear understanding of the clinical presentation and pathoanatomy, which must be specifically addressed by the surgical technique. Traumatic anterior instability is classically associated with the Bankart lesion and capsular tearing or stretching. The subluxating overhead athlete with internal impingement or “rotational instability” is identified arthroscopically by posterior-superior labral and undersurface rotator cuff tears in conjunction with anterior-inferior capsular laxity. Young females with global ligamentous laxity and excessive capsular redundancy profile the patient with multidirectional instability.

Basic Science: Thermal Affects on Collagen

Important “in vitro” studies have analyzed the effect of heat on the ultra-structure, histology, and biomechanical properties of collagen. The optimal temperature for maximizing the percentage of collagen shortening but avoiding excessive cell injury and compromise of tissue integrity appears to range between 65 and 75°C. The amount of tissue shrinkage achieved is dependent on both the duration and the temperature of the thermal treatment. Studies suggest that in the clinical setting, collagen shortening of between 15 and 30% occurs. After an initial inflammatory response to the thermal injury, collagen healing and maturation takes approximately 3 to 4 months to occur. It is postulated that one or a combination of the following processes lead to clinical improvement: capsular shrinkage, postoperative fibroplasia and capsular thickening (which alters the biomechanical properties of the tissue), or obliteration of afferent sensory receptors.

Indications

1. Traumatic anterior dislocation: acute or recurrent

2. Overhead athletes with subluxation and internal impingement

3. Posterior instability: acute or recurrent

4. Multidirectional instability: lower demand patients

Contraindications

1. Osseous deficiency: bony Bankart or large Hill-Sachs lesions

2. A failed previous arthroscopic or open stabilization procedure

3. Humeral avulsion of capsule (Hagl lesion)

4. Relative contraindication: extreme capsular laxity in a young athletic female

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