Michael J. Codsi

Rotator cuff repair augmentation in a canine model with use of a woven poly-L-lactide device.

BACKGROUND Despite advances in surgical treatment options, failure rates of rotator cuff repair have continued to range from 20% to 90%. Hence, there is a need for new repair strategies that provide effective mechanical reinforcement of rotator cuff repair as well as stimulate and enhance the intrinsic healing potential of the patient. The purpose of this study was to evaluate the extent to which augmentation of acute repair of rotator cuff tendons with a newly designed poly-L-lactide repair device would improve functional and biomechanical outcomes in a canine model. METHODS Eight adult, male mongrel dogs (25 to 30 kg) underwent bilateral shoulder surgery. One shoulder underwent tendon release and repair only, and the other was subjected to release and repair followed by augmentation with the repair device. At twelve weeks, tendon retraction, cross-sectional area, stiffness, and ultimate load of the repair site were measured. Augmented repairs underwent histologic assessment of biocompatibility. In addition, eight pairs of canine cadaver shoulders underwent infraspinatus injury and repair with and without device augmentation with use of identical surgical procedures and served as time-zero biomechanical controls. Eight unpaired, canine cadaver shoulders were included as normal biomechanical controls. RESULTS At time zero, repair augmentation significantly increased the ultimate load (23%) (p = 0.034) but not the stiffness of the canine infraspinatus tendon repair. At twelve weeks, the poly-L-lactide scaffold was observed to be histologically biocompatible, and augmented repairs demonstrated significantly less tendon retraction (p = 0.008) and significantly greater cross-sectional area (137%), stiffness (26%), and ultimate load (35%) than did repairs that had not been augmented (p < 0.001, p = 0.002, and p = 0.009, respectively). CONCLUSIONS While limiting but not eliminating tendon repair retraction, the augmentation device provided a tendon-bone bridge and scaffold for host tissue deposition and ingrowth, resulting in improved biomechanical function of the repair at twelve weeks.

Latissimus Dorsi Tendon Transfer for Irreparable Posterosuperior Rotator Cuff Tears: Surgical Technique

BACKGROUND The purpose of this study was to evaluate the clinical results of latissimus dorsi tendon transfer in patients with an irreparable posterosuperior rotator cuff tear to help determine which patient and anatomic factors affect clinical outcome. METHODS Fourteen patients with a latissimus dorsi tendon transfer were clinically evaluated with use of the PENN (University of Pennsylvania) shoulder score as well as with quantitative measurement of isometric muscle strength and the range of motion of both shoulders at a minimum of twenty-four months postoperatively. The anatomic results were evaluated with postoperative magnetic resonance imaging and electromyography. RESULTS Nine patients were satisfied with the outcome, had significant clinical improvement, and reported that they would have the operation again under similar circumstances. The other five patients were dissatisfied with the result and had significantly worse PENN scores, active elevation, and objective measures of strength. Eight of the nine patients with a good clinical result were male, and four of the five with a poor result were female. Patients with a good clinical result had had significantly better preoperative function in active forward flexion and active external rotation compared with the patients with a poor result. The magnetic resonance imaging demonstrated healing of the tendon to the greater tuberosity in twelve patients and equivocal healing in two. There was no significant atrophy of any of the transferred muscles. Electromyography demonstrated clear activity in the transferred latissimus muscle during humeral adduction in all fourteen patients, some electrical activity with active forward elevation in only one patient, and some electrical activity with active external rotation in six of the nine patients with a good clinical result. None of the patients with a poor clinical result demonstrated electrical activity of the transferred muscle with active forward flexion or external rotation. CONCLUSIONS Synchronous in-phase contraction of the transferred latissimus dorsi is a variable finding following the surgical treatment of irreparable posterosuperior rotator cuff tears, but when it is present it is associated with a better clinical result. Preoperative shoulder function and general strength influence the clinical result. Female patients with poor shoulder function and generalized muscle weakness prior to surgery have a greater likelihood of having a poor clinical result.

The three-dimensional glenoid vault model can estimate normal glenoid version in osteoarthritis.

Glenohumeral arthroplasty can involve correcting pathologic glenoid tilt or version. Predicting the physiologic glenoid version for a particular individual can be difficult. We propose using a previously validated, 3-dimensional, glenoid vault model as a template to predict normal glenoid version. Computed tomography scans of both shoulders were obtained in 14 subjects with unilateral glenohumeral osteoarthritis. Custom-developed graphic software was used to create a 3-D reconstruction of each scapula. Within the software, the vault model was placed in a best-fit orientation into each glenoid vault independently by 3 observers who were blinded to the contralateral scapula. Measurement differences between the glenoid and vault model were analyzed by repeated-measures analysis of variance. Standard errors of measurement (SEM) were calculated. Interobserver and intraobserver reliabilities were assessed. The healthy glenoid version averaged -7.0 degrees (SEM, 0.7 degrees ; range, 0 degrees to -14 degrees ). The arthritic glenoid version averaged -15.6 degrees (SEM, 0.7 degrees ; range, 1 degrees to -33 degrees ; P < .0001). The version of the implanted vault model measured -7.1 degrees (SEM, 0.7 degrees ; range, -1 degrees to -15 degrees ) on the healthy side and -7.2 degrees (SEM, 0.7 degrees ; range -2 degrees to -11 degrees ) on the arthritic side. Measurements between observers were not significantly different (P = .98). Interobserver and intraobserver correlation coefficients were 0.79 (P < .001) and 0.80 (P < .001). In the arthritic glenoid, the vault model reproducibly closely approximated the version of the normal contralateral glenoid, -7.2 degrees vs -7.0 degrees (P = .99) and is a novel and accurate method of estimating the normal glenoid version. This technique may be valuable in correcting pathologic glenoid version due to arthritis.

Normal glenoid vault anatomy and validation of a novel glenoid implant shape

Current glenoid implants are designed to be secured to the articular surface. When the articular surface is compromised, a glenoid component could be implanted if it obtained fixation from the endosteal surface of the glenoid vault. The first step for designing such a glenoid implant is to define the normal three-dimensional anatomy of the glenoid vault. The purpose of this study was to define the variations in glenoid vault shape in a large group of cadaver scapula. Computed tomographic (CT) scans of 61 normal scapulae (mean, 25-34 years) from the Haman-Todd Osteological Collection, with a wide range of sizes, were examined to define the normal glenoid vault anatomy. A custom software program was used to manipulate and measure the scans to determine the morphologic variations among the different glenoid vaults. From these data, we defined a unique glenoid vault shape and empirically developed 5 sizes to represent the study population of the 61 scapulae. A second group of 11 cadaver scapulae were used to validate the shape defined using the other 61. Prototype implants were placed into the real 11 scapulae using standard surgical techniques and then CT-scanned to analyze the shape of the glenoid vault. In the 61 scapulae, 85% of the points defining the endosteal surfaces vary among scapulae by less than 2 mm. For each of the 11 cadaver scapulae, the implant size used in the virtual computer implantation was the same size used for the plastic components placed into the cadaver scapulae. Fifty percent of the measured distances between the outer dimensions of the plastic models was within 2.4 mm of the glenoid endosteal surface. Eighty percent of the surface area of the plastic models was within 3.1 mm of the glenoid endosteal surface. Five percent of the dimensions were less than 1 mm and were considered to be areas of point contact. Before designing implants that can be used in pathologic glenoids, the shape of the normal glenoid vault must first be defined. This study defined a normal glenoid vault shape that can accommodate different sized scapula with 5 sizes. This glenoid shape may be used as a template to design a glenoid implant that obtains fixation within the glenoid vault.

The effect of screw position on the initial fixation of a reverse total shoulder prosthesis in a glenoid with a cavitary bone defect.

Patients with rotator cuff tear arthropathy can be treated successfully with a reverse total shoulder prosthesis. In patients with significant glenoid bone loss, achieving stable bone fixation can be challenging, as the surgeon must know when bone grafting is necessary and when the plan to implant the reverse total shoulder prosthesis should be abandoned because of the likelihood of early implant loosening. The purposes of this study were (1) to determine the initial stability of a metal glenoid implant fixed in a glenoid with a central cavitary defect and (2) to determine whether an altered screw configuration would sufficiently resist implant micromotion and, thereby, allow bone ingrowth to occur. The Delta III reverse total shoulder glenoid implant was fixed into foam scapulae with a uniform density similar to normal glenoid bone density. The control group implants were fixed into foam scapulae without a glenoid defect, by use of the standard surgical technique for screw placement. The second group was fixed into foam scapulae containing a central cavitary glenoid defect, by use of the standard surgical technique for screw placement. The central cavitary defect was meant to simulate the bone loss typically found after the removal of a loose pegged glenoid implant, and it was created with a 4-pegged glenoid drill guide. A third group was fixed into foam scapula with a central cavitary glenoid defect, with an experimental screw configuration by use of a posterior screw directed toward the spine of the scapula and an anterior screw directed inferior to the central peg. All specimens were loaded with 500 cycles of 1 body weight (70 kg) to simulate the forces generated during arm elevation that occur during the first 3 months after surgery. Micromotion between the implant and the foam bone was measured with a digital video motion analysis system (accuracy, +/- 2.6 microm). After loading of the implant with 70 kg for 500 cycles in the superior direction, the mean micromotion was 54 microm (SD, 22) in the control group, 159 microm (SD, 70) in the second group, and 86 microm (SD, 32) in the third group (P = 0.003). Fixing the posterior screw into the spine of the scapula and directing the anterior screw below the central peg decreased the micromotion of a metal glenoid implant fixed in a glenoid with a cavitary defect by 46% and, more importantly, reduced the micromotion below the critical threshold of 150 microm, which is necessary for bone ingrowth and long-term survival of the implant.

Thermal Capsulorrhaphy for the Treatment of Shoulder Instability

Thermal capsulorrhaphy has been used to treat many different types of shoulder instability, including multidirectional instability, unidirectional instability, and microinstability in overhead-throwing athletes. A device that delivers laser energy or radiofrequency energy to the capsule tissue causes the collagen to denature and the capsule to shrink. The optimal temperature to achieve the most shrinkage without causing necrosis of the tissue is between 65° and 75° centigrade. This treatment causes a significant decrease in mechanical stiffness for the first 2 weeks, and then, after the tissue undergoes active cellular repair from the surrounding uninjured tissue, the mechanical properties return to near normal by 12 weeks. If the thermal energy is applied in a grid pattern, then the tissue heals with more stiffness by 6 weeks. Clinical studies on thermal capsulorrhaphy for the treatment of multidirectional instability have shown a high rate of recurrent instability (12%-64%). The clinical studies on unidirectional instability showed much better recurrence rates (4%-25%), but because most of the patients also underwent concomitant Bankart repairs and superior labral anterior posterior lesion repairs, the efficacy of the thermal treatment cannot be ascertained. A randomized controlled trial would be needed to assess whether instability with Bankart lesions requires augmentation with thermal capsulorrhaphy. For the patients with microinstability who are overhead-throwing athletes, thermal capsulorrhaphy has shown varying results from a 97% rate of return to sports to a 62% rate of return to sports. Complications of this technique include temporary nerve injuries that usually involve the sensory branch of the axillary nerve and thermal necrosis of the capsule, which is rare.

Inter-rater reliability of an arthritic glenoid morphology classification system

To our knowledge, no independent analysis of the inter-rater agreement of the widely used Walch classification for osteoarthritic glenoid morphology has been performed. The computed tomography scans of 24 shoulders with primary osteoarthritis were used by 4 experienced shoulder surgeons to classify the glenoids independently according to Walch et al. The weighted kappa statistic was calculated to determine the inter-rater and intrarater agreement among observers. The overall inter-rater agreement for the Walch classification was fair (kappa = 0.37) when classified into the 5 types (A1, A2, B1, B2, and C). Agreement for the various subclassifications was as follows: A1, kappa = 0.22; A2, kappa = 0.33; B1, kappa = 0.17; B2, kappa = 0.32; and C, kappa = 0.86. When the classification system was simplified to just the 3 major types (A, B, and C), overall agreement was moderate (kappa = 0.44). Agreement for each type was moderate for A (kappa = 0.59) and B (kappa = 0.59) and almost perfect for C (kappa = 0.89). Overall intrarater agreement was fair (kappa = 0.37). We conclude that only fair agreement was found among experienced shoulder surgeons when classifying arthritic shoulders using the classification system of Walch et al. A glenoid classification scheme that relies more upon glenoid morphology and less upon humeral head position may demonstrate greater observer agreement and, therefore, may offer greater value.

Assessment of rotator cuff repair integrity using ultrasound and magnetic resonance imaging in a multicenter study

BACKGROUND This study compared ultrasound and magnetic resonance imaging (MRI) evaluation of the repaired rotator cuff to determine concordance between these imaging studies. METHODS We performed a concordance study using the data from a prospective nonrandomized multicenter study at 13 centers. A suture bridge technique was used to repair 113 rotator cuff tears that were between 1 and 4 cm wide. Repairs were evaluated with MRI and ultrasound at multiple time points after surgery. The MRI scans were read by a central radiologist and the surgeon, and the ultrasounds were read by a local radiologist or the surgeon who performed the ultrasound. RESULTS The concordance between the central radiologists MRI reading and the investigators MRI readings at all time points was 89%, with a κ coefficient of 0.60. The concordance between the central radiologists MRI and ultrasound readings at all time points was 85%, with a κ coefficient of 0.40. The concordance between the investigators MRI and ultrasound readings was 92%, with a κ coefficient of 0.70. CONCLUSIONS In the community setting, ultrasound may be used to evaluate the integrity of a repaired rotator cuff tendon and constitutes a comparable alternative to MRI when evaluating the integrity of a rotator cuff repair. Clinical investigators should compare their postoperative ultrasound results with their postoperative MRI results for a certain time period to establish the accuracy of ultrasound before relying solely on ultrasound imaging to evaluate the integrity of their rotator cuff repairs.

Natural Extracellular Matrix Grafts for Rotator Cuff Repair

The results of open or arthroscopic repair of the rotator cuff vary widely in the literature.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 The factors that have been shown to affect outcome relate to the technique of surgery,3,9,16, 17, 18 the size of the tear,9, 10, 11 the quality of the tissue and age of the patient,10,11,15 the chronicity of the tear,9, 10, 11,19,20 the degree of muscle atrophy, and the degree of tendon retraction.9, 10, 11,20 In many cases, the size of the tear is correlated with the degree of tendon retraction, muscle atrophy, and loss of tissue quality. Postoperative care influences outcome and is dependent upon the length and type of protection in the first 6 weeks after surgery,9,17,21 as well as the progression of the rehabilitation program from passive range of motion through active motion and resistance exercises. The larger and more chronic the tear, the more likely the patient will benefit from an abduction brace or pillow and a slower progression of the rehabilitation program.