The Harvard Shoulder Service has maintained a commitment, not only to excellent clinical care and teaching, but also to ongoing research. Our goal is to improve the practice of shoulder surgery. Our short and long-term goals deal with both basic science and clinical research questions. These goals are briefly summarized below.

I. Shoulder Arthroplasty:

Clinical Research: New third generation component designs have been developed which are based on critical analysis of the three dimensional anatomy of the proximal humerus. These humeral prostheses are distinguished from the original (second generation) modular components in that they allow for variation in neck-shaft angles, version, and humeral head off-set, relative to the humeral anatomic axis. We have recent-ly analyzed the anatomic accuracy of proximal humeral recon-struction using one type of third generation prosthesis and have compared it to a popular second-generation modular component. Clinical outcome was correlated with careful radi-ographic analysis. It was determined that the clinical outcome in short-term follow-up (two year minimum) was not affected by component design, although the third generation modular components do allow reconstruction of the humeral head to within 2 mm of the normal humerus. This was compared to a range of 1-2 cm variability from normal anatomy when the second-generation components were used for hemiarthroplas-ty. It remains unclear whether the anatomic accuracy has an effect on component durability. Our hypothesis is that com-ponent malpositioning is associated with more glenoid erosion and component loosening.

Dr. Warner is Chief, Harvard Shoulder Service, and
 Associate Professor of Orthopaedic Surgery, 
Harvard Medical School

Dr. Gill is an Attending Surgeon at Massachusetts 
General Hospital and Instructor of Orthopaedic
 Surgery, Harvard Medical School

Dr. Apreleva is a Principal Investigator at the Beth
 Israel Deaconess Medical Center Orthopaedic 
Biomechanics Laboratory and Instructor of 
Orthopaedic Surgery, Harvard Medical School.

Please address correspondence to:

GRB 606, Dept. of Orthopaedics
Massachusetts General Hospital
Boston, MA 02114

We have also evaluated the radiographic incidence of glenoid erosion following hemiarthroplasty in young patients with normal or near normal glenoid articular surfaces. We found that glenoid erosion did occur over a period of six months to 5 years and was correlated with clinical outcome. A greater degrees of erosion was associated with decreased func-tion and more pain. It appeared that humeral component malpositioning and stiffness may have contributed to glenoid wear due to increased joint reactive forces across the glenoid. The message of this study was that anatomic proximal humeral reconstruction combined with extensive soft-tissue releases might decrease the incidence of glenoid erosion in cases where a hemiarthroplasty is performed in a shoulder with a normal glenoid.

Ongoing clinical research will prospectively evaluate newer modular component designs in order to determine if clinical outcome is improved and if this is associated with anatomic reconstruction.

Basic Science:

The Shoulder Service Research Group has found a new home in the Orthopaedics Biomechanics Laboratory (OBL) at the Beth Israel Hospital. With the arrival of Maria Apreleva, Ph.D. from Pittsburgh, many projects are in planning. Guoan Li, Ph.D. joined the OBL in 1998, having become an expert in the field of robotics while in Pittsburgh. Dr. Li has graciously allowed the Shoulder Research Group access to his six degree of freedom robotic manipulator so that we can design studies to analyze joint reactive forces in the normal shoulder and the shoulder with simulated disease. The robot allows precise control of motion allowing not only kinematic measurement but also quantitative information regarding joint reactive forces. We hope to design an experimental set-up that will allow for operative manipulation of the shoulder. We will attempt to model articular defects of the humeral head, proximal humer-al arthroplasty with different types of components and positioning, and soft-tissue injuries. These studies should provide insight into forces across the capsule and labrum after capsu-lar repairs for instability. In addition, we expect to learn whether variable and adaptable third generation proximal humeral reconstruction affects forces across the glenoid. This information may help evaluate the potential durability of different types of proximal humeral reconstruction for arthritis.

II. Instability:

Clinical Research:

Clinical effectiveness and cost effectiveness of arthroscop-ic techniques of instability repair need to be evaluated when compared to the gold standard of open Bankart repair. We believe that these techniques offer reduced patient morbidity as well as clinical outcome equivalent to open techniques at a lower cost. We have therefore initiated a prospective study to evaluate arthroscopic Bankart repair and arthroscopic thermal capsulorrhaphy. The latter technique is particularly interest-ing, as it has gained a large following in the orthopaedic com-munity with very little scientific evidence of its effectiveness. Thermal shrinkage is based on an understanding that the col-lagen molecule has heat sensitive cross-links which denature above about 62°C. This causes the collagen molecules to uncoil from their orderly triple helix, crystalline arrangement, into a random coil with a shortened configuration. As a result, the tissue shrinks. It has been shown that the glenohumeral joint capsule may be shortened up to 50% of its original length, reducing laxity by as much as 40%. 1 Complications have also been reported. We have thus established a multi-center Thermal Capsulorrhaphy Study Group (TCSG), comprised of seven shoulder surgeons, in order to collect data on the clinical effectiveness, incidence of complications, and cost of this procedure.

Theoretically, arthroscopic Bankart repair offers advantages over open Bankart repair by having smaller incisions, being less invasive, and having less postoperative pain. A prospective study will be launched soon with Dr. Bert Zarins, Chief of the Sports Medicine Service at MGH, and the Department of Physical Therapy to determine if these assump-tions are true.

III. Rotator Cuff Disease:

Basic Science:

Many factors influence the outcome of rotator cuff repair. Besides initial strength of repair, one variable is the configuraof the tendon repair to bone. We are currently analyzing three-dimensional anatomy of the rotator cuff insertion and evaluating the anatomic configuration of different methods of rotator cuff repair. We believe this may provide insight into the preferred method(s) of repair, as surface area of contact of a tendon may have a bearing on success in healing after tendon repair.

Clinical Research: Management of massive and complex tears in revision situations continues to be the most challenging problem in rotator cuff surgery. We are particularly inter-ested in factors predicting outcome and have begun the initial steps in developing a research initiative with our colleagues in the magnetic resonance imaging facility (MRI) at the MGH. Our goal is to develop a method to quantitate rotator cuff muscle volume with three-dimensional visualization. This has been shown to be a prognostic factor for the outcome of ten-don repair (2). However, it is unknown to what degree atrophy of rotator cuff muscles may recover after repair. We hypothesize that the degree of muscle atrophy will correlate with tendon quality. Therefore, it may be possible to establish a MRI repara-bility index prior to surgery.

III. Summary and Overview:

The future of research and growth of the Harvard Shoulder Service is bright. This year has marked the beginning of our collaboration with the Dr. Christian Gerber and the University of Zurich in Switzerland. The Transcontinental Shoulder Fellowship offers a depth and breadth of academic and cultural experience unmatched by any other postgraduate educational experience in Shoulder. Future shared research projects are currently being planned. During the past year, over twenty visiting foreign orthopaedic surgeons have participated in the research activities of the Shoulder Service at Massachusetts General Hospital and Brigham and Women's Hospital. A formal visiting scholar program has been established, and over the next several years, a number of foreign orthopaedic surgeons will visit for six months to one year to participate in this programs. These visiting surgeons will come from Asia, Europe, South America, and Africa.

In addition, an additional shoulder surgeon will be hired during the coming year to augment our efforts in clinical care and basic research.

In aiming for the highest degree of excellence in the qual-ity of patient care, we continue to try to improve the practice of shoulder surgery. To accomplish this goal, we strive to answer important questions in basic science and clinical research by conducting well-designed studies in an atmos-phere of international collaboration.