Sunday, January 22, 2017

The risk of shoulder joint replacement infection is doubled by prior surgery on the shoulder

Is previous nonarthroplasty surgery a risk factor for periprosthetic infection in primary shoulder arthroplasty?

These authors reviewed 4577 patients including 2890 with total shoulder arthroplasties, 1233 with hemiarthroplasties, and 454 with reverse total shoulders 813 (18%).

Medical records and the surgeon’s clinical notes and operative reports were reviewed to determine the type of prior surgery. These were categorized as rotator cuff repair (353), open reduction and internal fixation (185), débridement for nonseptic reasons (235), acromioplasty (111), capsular repair (131), hardware removal (35), and other surgeries (152).

Deep postoperative infection of the shoulder was diagnosed in 68 patients (1.49%). An infected arthroplasty was diagnosed by the presence of 1 or both of the following: (1) positive joint fluid culture from needle aspiration, arthroscopic procedure, fluid obtained at surgery, or fluid draining from a wound communicating  with the humerus or (2) positive synovial or bone tissue culture. In those patients without a positive joint fluid culture, the presence of a clinical infection was determined when the treating orthopedic surgeon believed an infection was present on the basis of clinical presentation (history and physical examination), documentation in the surgeon’s note, and one or both of the following: (1) operative findings including purulent joint fluid, thick serosanguineous joint fluid, or the presence of necrotic synovial tissue or (2) a positive blood culture. The criteria for diagnosing 'infection' obviously affect the rate with which it is diagnosed. On one hand the authors recognize the possibility of 'culture negative' infection. On the other hand, it is recognized that cultures of joint fluid aspirates may be negative in the presence of positive deep cultures of tissue and explants as is emphasized in this link. The authors do not provide the data on the type of organisms cultured.

Of the 813 patients who had undergone previous surgery, 20 (2.46%) developed a deep postoperative infection. 

Of the 3764 patients who did not have previous shoulder surgery, 48 patients (1.28%) sustained deep shoulder infection. This difference was significant in both the univariate (P = .0094) and multivariate analyses (P = .0390). A higher number of previous surgeries was significantly associated with an increased risk of deep postoperative infection (P = .0272).

Younger age and male gender were significantly associated with a higher risk of deep postoperative infection (P = .0150 and P = .0074, respectively).  Patients undergoing SA for cuff tear arthropathy (HR, 3.49; 95% CI, 1.60-7.27; P = .0020) or in the setting of acute trauma (HR, 4.49; 95% CI, 1.33- 10.61; P = .0117) had a significantly increased risk of deep postoperative infection in the multivariable analysis.

Comment: The messages are clear: (1) surgeons need to be aware that even 'minor' surgeries (such as joint debridement) can increase the risk of infection in a subsequent joint replacement and (2) surgeons and patients need to discuss the fact that a shoulder arthroplasty on a previously operated shoulder has almost twice the risk of becoming infected. Surgeons need to consider obtaining 'preemptive' cultures at the time of arthroplasty in such cases and to be aware that a deviation from the expected postoperative course may represent the stealth presentation of a periprosthetic infection.

These authors are not the first to point out the relationship between prior surgery and shoulder arthroplasty infection. Their findings are similar to those of a prior article, our post on which is reproduced here:
Infection after primary anatomic versus primary reverse total shoulder arthroplasty.

These authors reviewed 814 primary total shoulder arthroplasties and found deep periprosthetic infections in 16: 6 anatomic total shoulders (aTSA)  and 10 reverse total shoulders (rTSA).

The surgical technique included the use of surgical hoods, limitation of operating room traffic, 
antibiotic prophylaxis with intravenous cefazolin (or clindamycin in cases of b-lactam allergy) at
least 30 minutes before the incision, followed by 3 additional postoperative doses. Preparation of the surgical site was with chlorhexidine.

The infections were determined by retrospective chart review. An infection was diagnosed by joint fluid culture or tissue/bone culture. Infections occurred in 7 women (44%) and in 9 men (56%).
The isolated causative organisms were Staphylococcus  spp in 7 patients (43.8%), Propionibacterium
acnes  in 7 (43.8%), Escherichia coli  in 1 (6.3%), and both Staphylococcus  spp and P acnes  in 1 (6.3%). The prior surgeries included rotator cuff repair in 5, Bankart repair in 1, ORIF for fracture in 1, and arthroscopic debridement/biceps tenotomy in 1. The patient with the E coli infection had no prior surgery.

Shoulders with previous nonarthroplasty operations undergoing primary TSA exhibited a significantly higher (P = .016) infection rate compared with shoulders with no operative history. 

Both aTSA and rTSA performed in previously operated-on shoulders demonstrated higher infection rates compared with shoulders with no prior operative intervention. 

Comment: We prepared this chart to make the data from this study a bit easier to grasp.

These data indicate that patients with prior surgery have an increased risk of sustaining an infection after shoulder arthroplasty - information that should be shared with candidates for this procedure.

It is likely that these numbers underestimate the number of infections in that we recognize that Propionibacterium infections may present as pain, stiffness and component loosening many years after the index procedure as described in this post.


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