Editorial Commentary: Shoulder Arthroscopy, Shoulder Hemiarthroplasty, and Total Shoulder Arthroplasty for Glenohumeral Osteoarthritis

Pyrocarbon hemiarthroplasty and the shoulder: biomechanical and clinical results of an emerging treatment option

While shoulder hemiarthroplasty is still used to treat young patients with shoulder pathology, the use of this procedure has substantially declined in recent years due to its significant complication profile. Glenoid wear with arthrosis is one of the major postoperative complications following shoulder hemiarthroplasty, and efforts to prevent this complication led many scientists to explore alternative weight-bearing surfaces on arthroplasty implants to decrease joint wear and improve patient outcomes. Pyrolytic carbon, or pyrocarbon, is a material that has better biocompatibility, survivorship, strength, and wear resistance compared to the materials used in traditional shoulder hemiarthroplasty. Pyrocarbon implants have been used in orthopedics for over 50 years; recently, their utility in shoulder hemiarthroplasty has garnered much interest. The purpose behind the use of pyrocarbon in shoulder hemiarthroplasty is to decrease the risk of progressive glenoid wear, especially in young active patients in whom joint preservation is important. Promising survivorship and outcomes have been demonstrated by recent studies, including limited glenoid wear following pyrocarbon hemiarthroplasty. Nevertheless, these clinical studies have been limited to relatively small case series with limited long-term follow-up. Accordingly, additional research and comparative studies need to be conducted in order to properly assess the therapeutic efficacy and value of pyrocarbon hemiarthroplasty.

Evidence-Based Practice Should Supersede Evidence-Based Medicine Through Consideration of Clinical Experience and Patient Characteristics in Addition to the Published Literature

On the surface, the benefits of evidence-based medicine (EBM) seem self-evident. However, reliance on the scientific literature alone has limitations. Studies may be biased, statistically fragile, and/or not reproducible. Reliance solely on EBM may ignore physician clinical experience and individual patient characteristics and input. Reliance solely on EBM may overvalue quantitative, statistical significance, resulting in a false sense of certainty. Reliance solely on EBM may fail to consider lack of generalizability of published studies to individually unique patients. The concept of evidence-based practice goes beyond EBM and incorporates (1) EBM, (2) clinical expertise, and (3) individual patient characteristics, values, and preferences. Even if branded as evidence-based, a suggested treatment may not be the best treatment. Evidence-based practice must be considered before determining what is best for our patients.

In vitro comparison of wear characteristics of PyroCarbon and metal on bone: Shoulder hemiarthroplasty

BACKGROUND

There are concerns regarding glenoid erosion with metal shoulder hemiarthroplasty. PyroCarbon may offer an alternative because of favorable wear characteristics and preservation of the glenoid. The purpose of this study was to assess in vitro bone wear characteristics of PyroCarbon relative to cobalt chromium alloy hemiarthroplasty in a shoulder wear simulator.

METHODS

Wear of PyroCarbon and cobalt chromium prostheses articulating with bone were characterized by means of bone wear penetration rate, changes to surface roughness, and wear particle analysis.

RESULTS

PyroCarbon prostheses produced significantly less damage to bone and were less damaged by the bone than cobalt chromium prostheses. Cobalt chromium testing was halted at approximately 320,000 cycles because the bone was consumed. Wear testing of PyroCarbon specimens continued through five million cycles. Linearized bone penetration rate, bone volume loss rate, and surface roughness for cobalt chromium test specimens were 30 times greater than for PyroCarbon.

CONCLUSIONS

Results demonstrate significantly less damage to bone in simulated shoulder function testing for PyroCarbon hemiarthroplasty implants relative to conventional cobalt chromium implants. Our study supports use of PyroCarbon in humeral head hemiarthroplasty as a viable alternative to conventional metal hemiarthroplasty. Further investigation of PyroCarbon performance in clinical settings is warranted.

Editorial Commentary: Multidirectional Shoulder Instability

Multidirectional shoulder instability responds to physical therapy and rehabilitation. For patients who fail rehabilitation, arthroscopic capsular plication seems the treatment of choice.

Editorial Commentary: Hamstring Tendon Regeneration After Autograft Harvest

While radiographic and histologic data show features of hamstring tendon regeneration after harvest for ligament reconstruction, we remain skeptical that hamstring regeneration is clinically meaningful. We cannot recommend reharvest for revision surgery.