Radiofrequency Microtenotomy for Elbow Epicondylitis: Midterm Results

We conducted a prospective, nonrandomized, single-center clinical study to evaluate the safety and midterm effectiveness of microtenotomy using a radiofrequency probe to treat chronic tendinosis of the elbow. All patients had failed conservative treatment for 6 months. The radiofrequency-based microtenotomy was performed using the Topaz Microdebrider (ArthroCare). Patients were followed annually for up to 9 years postoperatively. Pain status was documented using a visual analog scale self-reported measure. Eighty consecutive patients with tendinosis of the elbow were enrolled; 69 patients were treated for lateral epicondylitis and 11 for medial epicondylitis. The duration of follow-up ranged from 6 months to 9 years (mean, 2.5 years). Ninety-one percent of the patients reported a successful outcome. Within the lateral epicondylitis group, the preoperative visual analog scale improved from 6.9 to 1.3 postoperatively and demonstrated an 81% improvement (P ≤ .01). For the medial epicondylitis patients, the preoperative visual analog scale improved from 6.1 to 1.3 after surgery, a 79% improvement (P ≤ .01). No complications were reported. Radiofrequency-based microtenotomy is a safe and effective procedure for elbow epicondylitis. The results are durable with successful outcomes observed at 9 years after surgery.

Radiofrequency stimulation for potential healing of meniscal injuries in the avascular zone

We conducted this study to evaluate the effect of radiofrequency (RF) stimulation with suture repair on the healing of tears in the meniscal white-white zone. Fifty-four New Zealand white rabbits underwent surgically induced meniscal injuries within the white-white region. RF was applied using a 0.8-mm TOPAZ MicroDebrider RF wand (ArthroCare) at level 4 for 500 milliseconds. Rabbits were sacrificed at 28 and 84 days for gross and histologic analysis by 3 blinded observers and at 9, 28, and 84 days for biochemical examination. Biochemical analyses included evaluation of cell proliferation (3H-thymidine), as well as mitogenic (IGF-1, bFGF) and angiogenic (VEGF, αV) factors. Of specimens repaired with RF combined with suture, 19 (58%) showed a degree of gross morphologic and histologic healing. No significant healing was seen in specimens with either no repair or repair with suture alone. We observed a 40% increase in cellular proliferation when RF supplementation was used (P<.05). With regards to mitogenic and angiogenic markers (IGF-1, bFGF, VEGF, and αV), there was a significant increase in groups treated with RF at 9 and 28 days (P>0.05). RF supplementation of avascular zone meniscal repairs may lead to an increased healing response.

Visualization of the extra-articular portion of the long head of the biceps tendon during intra-articular shoulder arthroscopy

PURPOSE

To quantify the amount of the extra-articular long head of the biceps tendon (LHBT) seen during intra-articular shoulder arthroscopy by pulling the tendon into the joint with a probe through an anterior portal while viewing through a standard posterior portal.

METHODS

Intra-articular shoulder arthroscopy was performed on 10 forequarter cadaveric specimens. The extra-articular portion of the LHBT was evaluated by pulling the tendon into the joint with an arthroscopic probe inserted through an anterior portal. The tendon was marked at the pulley insertion on the humerus with a vascular clip before and after the tendon was pulled into the joint. An open deltopectoral approach was performed, and the amount of extra-articular tendon visualized was calculated as an absolute amount and in relation to nearby anatomic structures.

RESULTS

An additional 1.9 cm (range, 1.4 to 2.6 cm) of extra-articular LHBT was viewed by pulling the tendon into the joint with an arthroscopic probe through an anterior portal during shoulder arthroscopy. This represented 30.8% of the extra-articular portion of the tendon, 47.7% of tendon in the bicipital groove, and 76.3% of the tendon that lies under the area from the pulley insertion to the distal edge of the transverse humeral ligament.

CONCLUSIONS

During intra-articular shoulder arthroscopy, the extra-articular portion of the LHBT is incompletely visualized by pulling the tendon into the joint with a probe placed through an anterior portal while viewing through a standard posterior portal.

CLINICAL RELEVANCE

An additional extra-articular portion of the LHBT may be viewed by pulling the tendon into the joint with an arthroscopic probe during shoulder arthroscopy.

A biomechanical assessment of tendon repair after radiofrequency treatment

After acute tendon injury, rapid mobilization prevents adhesions and improves the ultimate strength of the repair. Radiofrequency (RF) ablation is proposed to enhance angiogenesis in the early stages of healing. The mechanism and effect of RF have not yet been described in an animal model of tendon injury. To investigate the biomechanical effect of bipolar RF on acute injury in a rabbit model of partial Achilles tendon transection and suture repair, RF-treated tendon repairs were compared to untreated tendons. Cross-sectional area, Young's modulus, and ultimate tensile strength were determined. At 6 and 12 weeks after repair, RF-treated tendons had significant increases in cross-sectional area (P<.001; P< .0001) and ultimate tensile strength (P<.0001; P<.01). Young modulus of RF-treated tendons was increased at 6 weeks but not at 12 weeks (P<.01) Compared with untreated tendons, RF-treated tendons showed faster return to mechanical integrity. This may allow earlier rehabilitation.

Augmentation of tendon healing with butyric acid-impregnated sutures: biomechanical evaluation in a rabbit model

BACKGROUND

Butyric acid (BA) has been shown to be angiogenic and to enhance transcriptional activity in tissue. These properties of BA have the potential to augment biological healing of a repaired tendon.

PURPOSE

To evaluate this possibility both biomechanically and histologically in an animal tendon repair model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A rabbit Achilles tendon healing model was used to evaluate the biomechanical strength and histological properties at 6 and 12 weeks after repair. Unilateral tendon defects were created in the middle bundle of the Achilles tendon of each rabbit, which were repaired equivalently with either Ultrabraid BA-impregnated sutures or control Ultrabraid sutures.

RESULTS

After 6 weeks, BA-impregnated suture repairs had a significantly increased (P < .0001) Young's modulus and ultimate tensile strength relative to the control suture repairs. At 12 weeks, no statistical difference was observed between these measures. The histological data at 6 weeks demonstrated significantly increased (P < .005) vessel density within 0.25 mm of the repair suture in the BA-impregnated group. There was also an associated 42% increase in the local number of myofibroblasts in the BA samples relative to the controls at this time. By 12 weeks, these differences were not observed.

CONCLUSION

Tendons repaired with BA-impregnated sutures demonstrated improved biomechanical properties at 6 weeks relative to control sutures, suggesting a neoangiogenic mechanism of enhanced healing through an increased myofibroblast presence.

CLINICAL RELEVANCE

These findings demonstrate that a relatively simple alteration of suture material may augment early tendon healing to create a stronger repair construct during this time.

The effect of butyric acid on normal tendons: a potential stimulus for extracellular matrix expression

We propose comparing angiogenic effects of butyric acid (BA)-impregnated suture vs control suture on an aged tendon model. Twenty-four 3-year-old rabbits underwent bilateral Achilles tendon exposure. BA-impregnated orthopedic suture was sutured into one side, and a control orthopedic suture into the contralateral side similarly. The rabbits were sacrificed at 7, 30, and 45 days and the tendons harvested for gross, histologic, and biochemical study. Histologically, there was increased vascularity/cell migration at all time points in the BA-treated tendons; proteoglycan expression (ie, safranin O staining) increased at 30 and 45 days. DNA concentration was significantly (P = .05) higher in the BA-treated tendon group relative to the control group at 7 days but was unchanged at 30 and 45 days. Similarly, messenger RNA (mRNA) expression of vascular endothelial growth factor (VEGF) was significantly (P = .05) higher in the BA-treated tendon at 7 days. A trend (P = .12) for higher expression in the BA group also was found at 30 days.

Nerve regeneration after radiofrequency application

BACKGROUND

Many patients with chronic tendinosis have experienced early pain relief after application of bipolar radiofrequency treatment. It is hypothesized that the mechanism of action may be the acute degeneration and/or ablation of sensory nerve fibers.

HYPOTHESIS

After ablation or degeneration by bipolar radiofrequency, nerve fibers will have the ability to regenerate with time.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen Sprague-Dawley rats were used in this study. These rats were divided into 3 groups (30, 60, and 90 days after bipolar radiofrequency). These rats were treated with 2 points of bipolar radiofrequency applications to the left hindpaws with the Topaz microdebrider device. Right hindpaws were used as the contralateral control. Tissues were processed for neural class III beta-tubulin or calcitonin gene-related peptide immunohistochemistry by using the free-floating avidin biotin complex technique. The numbers of neural class III beta-tubulin-immunoreactive and calcitonin gene-related peptide-immunoreactive nerve fibers in the epidermis were counted and compared with those in the contralateral control.

RESULTS

Although the numbers of nerve fibers demonstrated by both the antibodies of neural class III beta-tubulin and calcitonin gene-related peptide were significantly decreased (P <.0001) until 60 days after bipolar radiofrequency treatment, regeneration of the epidermal nerve fibers occurred 90 days after treatment.

CONCLUSION

Bipolar radiofrequency treatment induced degeneration of sensory nerve fibers immediately after treatment, but by 90 days posttreatment, there was evidence of complete regeneration.

CLINICAL RELEVANCE

Early degeneration followed by later regeneration of nerve fibers after bipolar radiofrequency treatment may explain long-term postoperative pain relief after microtenotomy for tendinosis.

Radiofrequency-based plasma microtenotomy compared with arthroscopic subacromial decompression yields equivalent outcomes for rotator cuff tendinosis

PURPOSE

This study aimed to determine whether radiofrequency (RF)-based plasma microtenotomy (microdebridement) was effective for treating chronic supraspinatus tendinosis.

METHODS

The institutional ethics committee approved the study design, and all patients signed informed consent forms. Patients (age range, 30 to 70 years) were considered for enrollment if 6 months of active conservative treatment had failed and they had Neer stage II impingement syndrome, positive radiographic evidence of type II acromion, and magnetic resonance imaging or ultrasound evidence of supraspinatus tendinosis. Patients (N = 60) were randomly assigned to undergo arthroscopic subacromial decompression or RF-based plasma microtenotomy. For microtenotomy, a bipolar RF-based probe (TOPAZ; ArthroCare, Austin, TX) was used to perform microdebridement in the supraspinatus tendon; patients did not undergo acromioplasty. Outcomes evaluation consisted of self-reported pain via a visual analog scale, as well as functional assessment (American Shoulder and Elbow Surgeons [ASES] survey, Constant score, and University of California, Los Angeles [UCLA] questionnaire). Statistical analyses were performed by use of factorial dependent-measures analysis of variance tests.

RESULTS

Age and baseline scores on the visual analog scale (mean +/- SD) were 52.0 +/- 6.7 and 53.2 +/- 6.6 years and 8.4 +/- 0.9 and 8.2 +/- 0.8 points in the microtenotomy and arthroscopic subacromial decompression groups, respectively. A significant reduction in pain (P < .001) and improved function (P < .001 for all measures) were observed in both groups postoperatively. Both treatment groups had almost identical longitudinal recovery profiles for pain relief (P = .416) and restoration of function (P = .964 for ASES score, P = .978 for Constant score, and P = .794 for UCLA score). At 1 year, the median pain score was 1.0, and all patients had ASES, Constant, and UCLA scores of greater than 90, greater than 80, and greater than 30, respectively.

CONCLUSIONS

Both procedures were associated with significant improvement postoperatively, but the RF-based plasma microtenotomy procedure draws into question the need for a more extensive procedure such as subacromial decompression in this patient population.

LEVEL OF EVIDENCE

Level I, therapeutic randomized controlled study.

Arthroscopic versus open rotator interval closure: biomechanical evaluation of stability and motion

PURPOSE

The purposes of this study were to investigate the differences between open and arthroscopic closure of the rotator interval (RI) on glenohumeral translation and range of motion. We also sought to determine if the addition of either an open or arthroscopic RI closure increases stability of the shoulder.

METHODS

Fourteen fresh-frozen (10 paired) cadaveric shoulder specimens were mounted in a custom testing apparatus, and glenohumeral translation and rotation were obtained by using an optoelectric tracking system (Optotrak Certus; Northern Digital, Ontario, Canada). Specimens were randomly allocated to either open (n = 7) or arthroscopic (n = 7) plication of the RI. The following were measured first with an intact and vented specimen and subsequently after an RI closure using either open or arthroscopic techniques: (1) range of motion in neutral and 90 degrees abduction; (2) anterior and posterior translation at neutral rotation; (3) anterior translation at 90 degrees abduction with external rotation; and (4) posterior translation at 90 degrees flexion with internal rotation.

RESULTS

Posterior stability was not improved from the intact state by either open (1.0-mm change) or arthroscopic (0.1-mm change) repair. The sulcus stability was improved in the open group (5.7 mm to 2.9 mm, P = .028), but not arthroscopically (5.1 to 4.1 mm, P = .499). Neutral anterior stability was improved after open repair (7.2 to 2.6 mm, P = .018), but not arthroscopically (2.3 to 2.4 mm, P = 0.5). However, anterior stability in external rotation (ER) at 90 degrees abduction was improved in the arthroscopic repair group (5.5 to 3.1 mm, P = .006). The mean loss of ER in neutral was greater in the open group (40.8 degrees) versus the arthroscopic group (24.4 degrees, P = .0038). The arthroscopic group showed an 11.7 degrees loss of ER in 90 degree abduction (P = .018) versus the open group loss of 4.8 degrees. There were no significant differences in loss of IR in either neutral or 90 degree abduction.

CONCLUSIONS

Posterior stability was not improved by either open or arthroscopic rotator interval repair, and sulcus stability only improved with the open technique. Anterior stability in neutral was improved after open repair and in the arthroscopic repair group with the arm abducted. There was a large loss of external rotation with both techniques.

CLINICAL RELEVANCE

This study suggests that arthroscopic RI closure adds little to the overall posterior and inferior stability of the shoulder joint, although anterior stability may be improved. There is a potentially large loss of external rotation after either repair method.

Pain relief through an antinociceptive effect after radiofrequency application

BACKGROUND

Many patients with chronic tendinosis have experienced early pain relief after application of bipolar radiofrequency treatment. Pathologic nerve ingrowth or nerve irritation in the tendon has been considered as a possible cause of the pain experienced with tendinosis.

HYPOTHESIS

Bipolar radiofrequency treatment will ablate nerve fibers, resulting in pain relief.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen Sprague-Dawley rats were used in this study. Eight rats were treated with 2 points of bipolar radiofrequency applications applied to the hind paws with the Topaz microdebrider device, 6 sham rats had a needle applied to the hind paws, and there were 4 control rats. Tissues were processed for neural class III beta-tubulin (TUJ-1) or calcitonin gene-related peptide (CGRP) immunohistochemistry by using the free-floating avidin-biotin complex technique. The numbers of TUJ1-immunoreactive and CGRP-immunoreactive nerve fibers in the epidermis were counted and compared with sham and control.

RESULTS

The number of nerve fibers demonstrated by both the antibodies of TUJ1 and CGRP were significantly decreased (P = .0002-.002) during the first 2 weeks after bipolar radiofrequency treatment. Macroscopically, the foot pad showed 2 dimples on the surface after bipolar radiofrequency treatment. Although it still showed a scar after 7 days, after 14 days it looked no different than the untreated contralateral control foot pad and foot pad of the sham group.

CONCLUSION

Bipolar radiofrequency treatment induced acute degeneration and/or ablation of sensory nerve fibers.

CLINICAL RELEVANCE

Degeneration or ablation of nerve fibers after bipolar radiofrequency treatment may explain the early postoperative pain relief after microtenotomy for tendinosis.

Meniscal debridement with an arthroscopic radiofrequency wand versus an arthroscopic shaver: comparative effects on menisci and underlying articular cartilage

PURPOSE

Meniscal debridement with an arthroscopic radiofrequency (RF) wand versus an arthroscopic shaver and their comparative effects on menisci and underlying articular cartilage were studied.

METHODS

When repair is not feasible, degenerative or post-traumatic meniscal tears often need debridement. Six fresh bovine knees were harvested, the tibial plateau was dissected free from the femoral articulation and placed in a saline bath at 28 degrees C, with 10% to 15% of the posterior horn of menisci debrided arthroscopically, and the surfaces debrided using a basket punch plus shaver, punch plus RF wand, RF wand alone, and untreated control. Treatment time of each case was 24 seconds at wand power 7. We characterized an injury zone, as well as viability and metabolic activity of meniscal cells and tibial articular cartilage chondrocytes.

RESULTS

Chondrocyte viability of the tibial articular surface was 96% to 98%. We saw no differences in viability or injury zone (0 to 150 microm) among debrided groups or versus the control for any experimental surface, with no significant difference in metabolic activity in menisci debrided surfaces versus control. Meniscal viability was variable with analyses showing substantial levels (150 to 500 microm) of cell death in debrided and control groups. Metabolic activity in treated meniscus was lower than in cartilage specimens. No significant differences were observed among treatment groups versus control.

CONCLUSIONS

Focal areas of chondrocyte cell death were not seen. Meniscal samples showed cell death (150 to 500 mum) throughout the tissue.

CLINICAL RELEVANCE

Debridement of menisci with a bipolar RF wand produces levels of cell injury and death similar to those of debridement with a basket punch mechanical shaver. The RF wand did not harm underlying articular surfaces and produced a precise cut to the meniscal surface.

Arthroscopy of the subtalar joint and arthroscopic subtalar arthrodesis

Subtalar arthroscopy has become a valuable adjunct to the tools used in lower extremity surgery. For the past 25 years, ankle arthroscopy has been in vogue for treating a variety of conditions. Subtalar arthroscopy has more treatment limitations and is more technically difficult to perform than ankle arthroscopy because of the anatomic confines and structure of the subtalar joint. Most procedures are performed on the posterior aspect of the subtalar joint. The subtalar joint is composed of three articulations (posterior, middle, and anterior facets) and is surrounded by a variety of intra-articular and extra-articular ligaments, whose anatomy must be fully understood before attempting this procedure. Subtalar arthroscopy may be indicated for diagnostic purposes and for débridement of synovial impingement syndromes in the sinus tarsi. It may be used to examine loose bodies or osteochondral lesions, to address fractures of the lateral process of the talus, and to evaluate subtalar instability to determine appropriate stabilization methods. Arthroscopic subtalar arthrodesis also has gained credibility over the past 10 years as an acceptable surgical procedure. Arthroscopic evaluation of subtalar instability is useful in planning the appropriate stabilization. Subtalar arthroscopy is usually performed with the patient in the lateral decubitus position without traction. Anterior and posterior portals as well as an accessory anterior portal are usually necessary to perform all of the above procedures. Because of the limited confines of the joint, care must be taken to prevent any articular cartilage damage. When performing subtalar arthroscopy in conjunction with ankle arthroscopy, the subtalar arthroscopy should be performed first to avoid excessive extravasation from the ankle arthroscopy, which could obscure entry to the subtalar joint. Complications of subtalar arthroscopy are similar to those encountered in ankle arthroscopy, such as damage to the sural and superficial peroneal nerves.

Microtenotomy using a radiofrequency probe to treat lateral epicondylitis

PURPOSE

To evaluate the safety and effectiveness of microtenotomy using a radiofrequency (RF) probe to treat chronic tendinosis of the common extensor tendon origins of the elbow (lateral epicondyle).

TYPE OF STUDY

Prospective, nonrandomized consecutive case series.

METHODS

The average age of the 13 patients was 48.3 +/- 5.5 years. Before receiving the microtenotomy, all patients had tendinosis symptoms for 6 months or longer and had failed conservative treatment. The RF-based microdebridement was performed on the symptomatic tendon using the TOPAZ Microdebrider device (ArthroCare, Sunnyvale, CA). Patients were followed-up at regular postoperative intervals for 24 months. Pain status was documented using a visual analog scale self-reported measure. Functional outcome was assessed using the upper limb DASH evaluation and grip-strength measures. Quality of life assessment was evaluated using the SF-36 questionnaire. Magnetic resonance imaging was performed at regular intervals over the follow-up period.

RESULTS

Patients reported significantly reduced pain from baseline at the 7- to 10-day postoperative examination (P < or = .01). Pain reduction was statistically stable from 7 to 10 days through the 24-month postoperative period (P < or = .01). Limb-specific functional outcomes and quality of life scores were improved over baseline values. There were no perioperative or postoperative complications related to the procedure.

CONCLUSIONS

The RF-based microtenotomy procedure was safe and effective through at least 2 years. This procedure provides a valuable addition for treating patients with lateral epicondylitis associated with tendinosis who have failed conservative therapy.

LEVEL OF EVIDENCE

Level IV.

Chondrocyte viability and metabolic activity after treatment of bovine articular cartilage with bipolar radiofrequency: an in vitro study

PURPOSE

Some controversy exists regarding the effects of radiofrequency (RF) probes on articular cartilage. To further elucidate these effects, we examined the chondrocyte viability and metabolic activity after treatment of fresh bovine articular cartilage with bipolar RF probes.

TYPE OF STUDY

In vitro assessment.

METHODS

Three fresh bovine knees served as a baseline control for chondrocyte viability, yielding 6 samples (1 from each medial femoral condyle and 1 from each lateral femoral condyle). After the baseline expected chondrocyte viability was determined, 3 additional bovine knees served as the experimental specimens for the study. Under sterile conditions, 2 different bipolar RF probes were used to treat the articular surface in a light contact mode, moving at a linear rate of 3 to 4 mm/s to provide tissue debridement. Full-thickness articular cartilage was then harvested from each of the treatment areas. Six samples per probe were then assessed for chondrocyte viability using fluorescent double-staining followed by confocal microscopy; 6 samples per probe were assessed for metabolic activity using an 35SO4 incorporation assay; and 12 additional untreated samples were obtained to serve as controls for viability (n = 6) and metabolic activity (n = 6).

RESULTS

The depth of chondrocyte death (mean +/- standard deviation) was 109.4 +/- 22.1 microm after treatment with the ACD-50 probe, and was 172.3 +/- 34.3 microm after treatment with the 2.5-mm/90 degrees probe. The 35SO4 uptake (mean +/- standard deviation) was 2584 +/- 1388 cpm/mg dry cartilage for the ACD-50 probe and 1995 +/- 852 cpm/mg of dry cartilage for the 2.5-mm/90 degrees probe. The 35SO4 uptake for the control was 2647 +/- 1380 cpm/mg dry cartilage.

CONCLUSIONS

The 2 probes tested created a well-controlled debridement with smooth edges and a defined margin of chondrocyte death that extended approximately 100 to 200 microm deep to the treatment area. There does not appear to be a significant effect on the metabolic activity of the chondrocytes adjacent to the treatment zone, but with the small sample size we lacked sufficient statistical power to definitively determine these effects.

CLINICAL RELEVANCE

The 2 bipolar radiofrequency probes tested created a well-controlled debridement in normal articular cartilage with smooth edges and a defined margin of chondrocyte death that extended approximately 100 to 200 microm into the treatment area.

Bioabsorbable implants in orthopaedics: new developments and clinical applications

The use of bioabsorbable implants in orthopaedic surgical procedures is becoming more frequent. Advances in polymer science have allowed the production of implants with the mechanical strength necessary for such procedures. Bioabsorbable materials have been utilized for the fixation of fractures as well as for soft-tissue fixation. These implants offer the advantages of gradual load transfer to the healing tissue, reduced need for hardware removal, and radiolucency, which facilitates postoperative radiographic evaluation. Reported complications with the use of these materials include sterile sinus tract formation, osteolysis, synovitis, and hypertrophic fibrous encapsulation. Further study is required to determine the clinical situations in which these materials are of most benefit.

Arthroscopic ankle arthrodesis

The obvious socioeconomic advantages are quite dramatic, with early weight-bearing and AFO immobilization allowing patients an early return to work. Outpatient surgery is a cost-effective benefit. Patient satisfactions as well as comfort are greatly enhanced, requiring only oral pain medication. All patients have tolerated their postoperative regimen and same-day discharge. Arthroscopic subtalar arthrodesis is a technically demanding procedure that requires some rather advanced arthroscopic skills to perform. Joint access is tight, restricted, and requires small instrumentation. Deformities cannot be corrected; therefore, at this stage, a fusion in situ must be considered. The learning curve is certainly far steeper because of the smaller patient population available for enhancing surgical skills. Overall, this procedure has stood the test of time and follow-up. The results appear to be excellent in terms of patient satisfaction, fusion rate time until union, and postoperative morbidity. The recognition and enhancement of this technique as well as the development of more advanced technology will certainly allow this arthroscopic subtalar arthrodesis technique to mature even further over time.

Multiquadrant digital analysis of shoulder capsular thickness

PURPOSE

Nonablative thermal capsular shrinkage has been developed in an attempt to address the plastic capsule deformation thought to cause increased rates of recurrent instability following arthroscopic stabilization procedures. Although the temperature required to optimize collagen shrinkage is known, a safe depth of thermal penetration, in various locations about the shoulder capsule, has not been defined. The purpose of this study was to measure shoulder capsule thickness by quadrant and circumferentially from the glenoid to the humerus so that thermal energy in shoulder procedures can be more precisely applied to limit possible injury to pericapsular structures.

TYPE OF STUDY

This is an anatomic study using a cadaveric shoulder specimens.

MATERIALS AND METHODS

Soft tissue was dissected from 8 fresh cadaveric shoulders to isolate intact glenohumeral joint capsules. The humeral insertion was released and the capsule was cut into 6 longitudinal quadrants around the glenoid. The capsule specimens were then flash frozen and stored at -80 degrees C. Quadrant tissue was cut into longitudinal sections 14 to 16 microm wide and stained with hematoxylin and eosin. The specimens were then digitized under a dissecting microscope and measured using computer imaging software at approximately 4-mm intervals. Two-way analysis of variance (ANOVA) was performed on the measurements of the intact capsule specimens 2.5 cm off the glenoid. Humeral insertion data were recorded separately.

RESULTS

A total of 248 separate measurements were made throughout the capsule in 8 specimens. Capsular thickness increased from an average of 2.42 mm anteriorly to 2.80 mm in the inferior capsular pouch and again thinned to 2.22 mm posteriorly. Global shoulder capsule thickness ranged from 1.32 to 4.47 mm. When analyzed by position, from glenoid to humerus, a general thinning was noted with a mean thickness of 3. 03 mm at the glenoid to 2.17 mm at the humeral insertion. Two-way ANOVA showed a significant thickness variation along the specimen (P <.05), a nearly significant thickness variation with regard to quadrant (P <.03), and no significant interaction (P >.07) when applied to specimen measurements approximately 2.5 cm off the glenoid.

CONCLUSIONS

The thickness of the shoulder capsule ranges from 1.32 to 4.47 mm, with a significant thinning laterally from the glenoid to the humerus. Further, capsule thickness ranges from 2.76 to 3.18 mm in the regions in closest proximity to the axillary nerve. These data may help determine the proper amount of thermal penetration necessary when performing shrinkage procedures and provide safety guidelines to limit the depth of thermal penetration to avoid possible injury to pericapsular structures.

Current uses of radiofrequency in arthroscopic knee surgery

Radiofrequency energy is a promising new technology in arthroscopy. Further basic science work is needed to define the mechanical characteristics of tissues in vivo at different times postoperatively. Long-term clinical follow-up studies are needed to determine the useful applications of this technology in the future.