Septic failure of a shoulder arthroplasty due to a low-grade infection is generally called septic loosening. However, it is often not investigated if a prosthesis is genuinely loose. We present a case of a failed resurfacing prosthesis in a 70-year-old woman. This prosthesis failed due to a low-grade infection and a revision procedure was mandatory. All intraoperative cultures were positive and revealed a combination of bacteria. Nevertheless, histology revealed a macroscopic and a microscopic stable prosthesis with full osseointegration beneath the prosthesis. The general conception is that an infection leads to interface formation (with neutrophils) and loosening of the prosthesis. We debate this with the presentation of this case of a failed shoulder prosthesis and we think that periprosthetic infection and septic prosthetic loosening are two different entities.
Infectious failure of a shoulder arthroplasty is a devastating complication requiring revision surgery. In orthopedic literature, a differentiation between septic and aseptic prosthetic loosening is often made.[–] It is thought that cellular processes of the periprosthetic membrane with mobility of the implant lead to disintegration, osteolysis, and bone defects causing (septic) prosthetic loosening.[,,] We present a case of a patient with a failed uncemented resurfacing shoulder arthroplasty due to a low-grade infection. Nevertheless, histology revealed a fully osseointegrated prosthesis. To our knowledge, a prosthetic failure due to low-grade infection with a histological proven stable prosthesis has never been reported.
Since this initial period, she suffered progressive shoulder pain. At examination, there was a painful arc and the supraspinatus resistance test was painful, but there were no clinical signs of a cuff rupture. It was thought that rotator cuff tendinitis caused this pain and an arthroscopic subacromial decompression was performed. Preoperative 1 gr of cefazoline was given. During surgery the rotator cuff was intact. At this time, an infection was not considered and therefore the glenohumoral joint was neither inspected nor aspirated. However, the subacromial decompression did not relieve the complaints and the range of motion gradually decreased. At 2 years after the arthroplasty, the patient had pain on the anterior side of the shoulder, mild rest pain, increased pain whilst lifting, and a restricted forward flexion of 90° and external rotation of 50°. No clinical infectious signs were present and the cuff seemed intact. Her erythrocyte sedimentation rate (ESR) was slightly elevated since the first operation (between 30 and 45) with a normal C-reactive protein (CRP). However, the biochemical markers are not completely reliable for an infection due to her diverticulitis. The X-rays showed a well-positioned prosthesis without signs of loosening and some progression in glenoid erosion . To exclude an infection, a culture of intra-articular fluid (obtained by fine-needle aspiration) was done, which was negative.
These findings led to the conclusion that the resurfacing prosthesis failed due to a painful low-grade infection, without loosening of the prosthesis. According to the advice of the microbiologist, prolonged antibiotic regiment was started until the ESR and CRP normalized after 3 months. The rehabilitation period was longer than after the first operation, but uneventful and no wound problems occurred. At the last follow-up, 24 months postoperative, she was satisfied with her shoulder. She had a pain-free active forward flexion of 140°, endorotation of 70°, and exorotation of 30°. There were no clinical or biochemical signs of infection and the X-ray showed a correct position of the prosthesis with no signs of loosening .
In our case, the histological analysis of the shoulder prosthesis did not fit the standardized histological classification. This was due to the fact that we did not find a periprosthetic interface as the bone was fully integrated onto the hydroxyapatite-coated undersurface of the prosthesis. This is in contrast to the theory that an infection leads to interface formation and subsequently loosening of the prosthesis.
In conclusion, we present a case of a failed hemi-shoulder prosthesis due to a periprosthetic infection, which was histologically fully osseointegrated. The general conception is that an infection leads to interface formation (with neutrophils) and loosening of the prosthesis. We debate this with the presentation of this case and we think that periprosthetic infection and septic prosthetic loosening are two different entities.
The major causes of failure in hip replacement are: dislocation of the joint, loosening of the stem and cup, and failure of the stem. Dislocation of the prosthesis can occur immediately after surgery if you move your leg into a prohibited position. It is therefore necessary to avoid extremes of , , and for about 12 weeks until a thick capsule forms around the artificial joint. If you dislocate, you will need to be put under deep anaesthesia so your hip muscles can relax sufficiently to allow the artificial hip joint to be reduced. Care should be taken to avoid dislocation as the sciatic nerve, which supplies large leg muscles, is in danger of damage when your hip dislocates.
Replacement involves shaping or cutting the bone ends and applying a metal or polyethylene component to the surface. Usually both sides of the joint are replaced. One can either replace all parts of the knee, which is a total knee replacement or just one part of the knee, which is a partial replacement. Like osteotomies, partial replacement can only be used for certain patterns of osteoarthritis. In general we try to put off joint replacement procedures for as long as possible because of concerns about long-term wear and loosening. In addition, replacement procedures are only compatible with low impact sporting activities. Golf, social or doubles tennis, cycling, and snow skiing are reasonable whereas running, basketball, netball, or any type of football should not be considered, because of the risk of premature wear and loosening of the prosthesis.