Three Cases of Femoral Stem Failure in Rotating Hinge Revision Total Knee Arthroplasty: Causes and Surgical Considerations.

Catastrophic failure of stemmed components in arthroplasty is an uncommon but a serious complication. Stem fractures and techniques for addressing these have been described following hip arthroplasty but much less so following total knee arthroplasty (TKA). We review three cases of catastrophic failure of the stem in rotating hinge revision TKA prostheses. We discuss the possible mechanism of failure and review the current literature addressing this topic. Metaphyseal support needs to be optimized in order to minimize load transfer to the stem and to the junction (and the risk of fracture) if a modular component is used. When constrained components are used, radiographs need to be carefully assessed for signs of proximal loosening. Nonmodular stems are also an option in this situation.

The characterisation of unexplained pain after knee replacement.

BACKGROUND: The aims of this study were to characterise the pain experienced by patients with chronic pain after knee replacement (KR), in whom no apparent 'orthopaedic' problem could be identified, and to establish how many have pain sensitisation problems (including neuropathic pain). METHODS: A total of 44 patients were prospectively evaluated at a multidisciplinary tertiary referral clinic by an orthopaedic surgeon, pain specialist, rheumatologist and physiotherapist. These patients had been pre-screened by an orthopaedic surgeon to remove cases where there was an obvious cause of pain that could be treated with revision surgery. They were then followed up to find out whether any subsequent interventions had occurred. RESULTS: The mean time since surgery was 29 months (range: 3-108 months), and 18% were revision KR. Patients were evaluated for symptoms of nociceptive pain, allodynia, pains elsewhere and psychosocial factors. The patients were categorised into nociceptive pain 43% (n = 19), pain sensitisation 25% (n = 11) and mixed pain 32% (n = 14). Mean Visual Analogue Score (VAS) pain scores were 6.7/10 with high scores for both constant (66%) and intermittent (70%) pain elements, and pain caused high levels of interference with life. Fifty percent suffered depression and 25% suffered widespread pains (more than three pains elsewhere in the body). Patients with widespread pains suffered more pain (p = 0.01) and higher rates of both pain sensitisation (p = 0.07) and thermal allodynia (p < 0.04). CONCLUSION: Patients after KR can experience severe pain that interferes with their lives, depression and many have pain sensitisation problems rather than any local, nociceptive cause. We advocate screening patients with unexplained pain after KR for pain sensitisation problems, pains at other sites and depression. Appropriate further treatment and multidisciplinary interventions can then be arranged.