Characteristics and outcome of 16 periprosthetic shoulder joint infections

PURPOSE

Shoulder arthroplasties are increasingly performed, but data on periprosthetic joint infections (PJI) in this anatomical position are limited. We retrospectively investigated the characteristics and outcome of shoulder PJI after primary arthroplasty from 1998 to 2010 in a single centre.

METHODS

Periprosthetic joint infection was defined as periprosthetic purulence, presence of sinus tract or microbial growth. A Kaplan-Meier survival method was used to estimate relapse-free survival of prosthesis.

RESULTS

From 1,571 primary shoulder prostheses, we evaluated 16 patients with a PJI at different stages, i.e, early (n = 4), delayed (n = 6) and late (n = 6) infections. The median patient age was 67 (range 53-86) years, and 69 % were females. The most commonly isolated microorganism was Propionibacterium acnes in 38 % of patients (monobacterial in four and polymicrobial in two patients). In 14 of the 16 patients, surgical interventions consisting of debridement and implant retention (6 patients), exchange (7) and explantation (1) were performed. Four patients had a relapse of infection with P. acnes (n = 3) or Bacteroides fragilis (n = 1). The relapse-free survival of the prosthesis was 75 % (95 % confidence interval 46-90 %) after 1 and 2 years, 100 % in six patients following the treatment algorithm for hip and knee PJI and 60 % in 10 patients not followed up. All but one of the relapses were previously treated without exchange of the prosthesis.

CONCLUSIONS

As recommended for hip and knee PJI, we suggest treating shoulder PJI with a low-grade infection by microorganisms such as P. acnes with an exchange of the prosthesis. Cohort studies are needed to verify our results.

Cross-cultural adaptation, reliability and validity of the German Shoulder Pain and Disability Index (SPADI)

OBJECTIVE

To cross-culturally adapt the Shoulder Pain and Disability Index (SPADI) from English into German, and to test the reliability and validity of the German version.

METHODS

Cross-cultural adaptation of the SPADI was performed according to international guidelines. One hundred and eighteen patients who had undergone shoulder arthroplasty, on average 4 yr previously, completed a questionnaire booklet containing the German SPADI, the Short Form 36 (SF-36), the Disability of the Arm, Shoulder and Hand (DASH) questionnaire, and the American Shoulder and Elbow Surgeons (ASES) questionnaire for the shoulder to assess SPADI's construct validity. One week later, they completed the SPADI again to assess test-retest reliability.

RESULTS

The six-step cross-cultural adaptation procedure revealed no major problems with the content or language. The intraclass correlation coefficients for the individual items of the SPADI were between 0.68 and 0.89, and that for the SPADI total score was 0.94. The SPADI total score showed a correlation of 0.61-0.69 with the SF-36 physical scales, of 0.88 with the DASH and of 0.92 with the ASES.

CONCLUSIONS

The German SPADI is a practicable, reliable and valid instrument, and can be recommended for the self-assessment of shoulder pain and function.

[Shoulder joint instability after primary arthroplasty]

Instability is one of the most common complications after shoulder arthroplasty. The literature cites subluxation or luxation to occur between 0% and 38% in various studies. Instabilities may present either as subluxation or frank dislocation, and may be directed in an anterior, posterior, inferior or, depending on the state of the rotator cuff, cranial direction. The stability of any shoulder joint is given by the balance of the muscles directing the forces around the shoulder joint in association with the passive stabilizers of the shoulder joint capsule as well as the bony contours between glenoid and humeral head. Any disturbance of this delicate balance will lead the shoulder into instability, particular so if bony erosion patterns such as posterior glenoid wear in osteoarthritics will develop subluxation early on. Therefore implantation of any prosthesis is required to be done in the appropriate version as to avoid secondary instability through the prosthetic components. In the study undertaken here instability was found to be the most common complication in 44 shoulder revision surgeries. The result with an average Score of 41.9 recorded after Constant demonstrates that the excellent and good results obtained with primary arthroplasties can not be expected in revision surgery. Posterior instability may be present just as well as the more easily observed anterior instability. Separate to frank luxation or instability is the late cranialisation of the rotator cuff deficient shoulder which, although resulting in many cases in superior anterior subluxation, will mostly be seen as a late complication after arthroplasty.

[Indications for shoulder prosthetics in degenerative and inflammatory diseases]

Shoulder arthroplasty has since it's more widespread introduction in the early seventies found a general acceptance as an excellent tool for treating late stage arthritis of the shoulder joint. The indications will vary from primary osteoarthritic disease to inflammatory diseases such as rheumatoid arthritis, or psoriatric arthritis. It is also used as a primary tool in multifragmented shoulder fractures, which can not be restored anatomically, or are felt at risk for avascular necrosis. The surgeon setting out for this procedure has to decide whether a total arthroplasty is required in cases with glenoid destruction, or at risk of developing secondary degenerative changes in the glenoid early on. A hemiarthroplasty will only replace the humeral side of the joint, but while well accepted in the fracture patient, the arthritic patients tend to fare better with a total joint replacement for pain relief.

[Infection following shoulder and elbow arthroplasty. Diagnosis and therapy]

The rate of infection reported in recent publications is 0.8% after shoulder arthroplasty and ten times higher (8.1%) after elbow arthroplasty. The figures for shoulder arthroplasty correspond well with our own rate of revision for infection of 0.5% after 363 primary shoulder replacements. However, our average rate of revision for infection (1.8%) after 278 GSB-III elbow arthroplasties was considerably lower and included rheumatoid as well as post-traumatic indications. Our experience concerning etiologic factors, nature, diagnosis, treatment options, and long-term consequences of superficial and deep infections after shoulder and elbow arthroplasty are discussed for each joint separately and in relation to the literature.