Introduction: The principal aim of total knee replacement (TKR) surgery is to relieve chronic knee pain. However, following recuperation from surgery, 10–30% of patients report chronic pain in the replaced joint. There has been little research investigating the impact of this continuing pain on patients’ lives or exploring the way in which individuals adjust to this pain. Therefore, the aim of this study is to explore, from their own perspectives, patients’ experiences of chronic pain following this end-stage treatment of TKR.

Participants and Methods: Participants were twenty-eight patients who had undergone a TKR with the National Health Service at Bristol, Southwest UK, and who reported chronic pain in the replaced knee joint at least one year post-operatively. Purposive sampling was used in order to recruit participants both of a range of ages and with moderate to severe chronic pain. In-depth, semi-structured interviews were conducted with participants. Interviews explored individuals’ perceptions of the identity of their condition, its cause, duration and consequences and whether they had any control over it. Data was analysed using thematic analysis.

Results: Analysis revealed that, while all participants experienced chronic pain which necessitated the use of pain relief medication, there was great variation among individuals in terms of their adjustment to their condition: while some were well adjusted and accepting of their pain, for others the pain constituted a source of ongoing distress.

Regardless of their expectations concerning level of pain following TKR, those participants who perceived an improvement in pain as a result of their TKR were less likely to expect a cure for their residual pain and were either very well or reasonably well adjusted to the pain. Nevertheless, those who had moderate expectations of outcome were more likely to perceive an improvement than those with high expectations. Those individuals who reported having held high expectations of TKR outcome and subsequently experienced increased pain were likely to experience distress in relation to their pain; those who also felt that a cure for their current pain may be possible experienced particularly high levels of distress.

Discussion: The findings show the significance of cognitions, beliefs and expectations to individuals’ adjustment to chronic pain following TKR. They highlight a group of patients for whom adjustment may be problematic, which could indicate the need for assessment and intervention. There could be potential for surgeons to influence their patients’ adjustment positively by attempting to instil realistic expectations both prior to surgery and when chronic pain is experienced after recovery from TKR.

Introduction: The surface of articular cartilage is adapted to low-friction movement. It is important for lubrication, resists shear and compression, and allows transfer of fluid, nutrients and metabolites between synovial fluid, matrix and cells. Surface damage is common following trauma and in early osteoarthritis. The use of intra-articular hyaluronan (visco-supplementation), or oral glucosamine and chondroitin, is claimed to enhance surface protection and/or repair. To validate such treatment biologically, a better understanding of normal structure and function of the cartilage surface is required.

Methods: The surface of femoral condylar cartilage of sheep was examined using transmission electron microscopy (TEM), scanning electron microscopy and polarising microscopy. Fresh specimens were obtained before and after wiping the surface with lens tissue.

Results: TEM of un-wiped normal cartilage showed a thin surface coating of amorphous electron-dense material containing occasional microvesicles and bundles of detaching collagen fibrils. In wiped cartilage this coating was absent, suggesting the superficial layer described in previous studies (lamina splendens of MacConaill), is an adherent coating, probably aggregated proteoglycan, hyaluronate and matrix degradation products. The definitive cartilage surface was a smooth network of fine collagen fibres supported by a mesh of collagen containing microvesicles and particles. More deeply a denser layer of collagen ran parallel to the joint surface. The most superficial zone would allow rapid surface exchange of fluid and particles while the deeper collagen would protect the underlying cells and limit fluid moving deeper during joint loading.

Conclusions: The findings have implications for therapy aimed at cartilage surface protection and/or repair.

The three-dimensional architecture of bovine articular cartilage collagen and its relationship to split lines has been studied with scanning electron microscopy. In the middle and superficial zones, collagen was organised in a layered or leaf-like manner. The orientation was vertical in the intermediate zone, curving to become horizontal and parallel to the articular surface in the superficial zone. Each leaf consisted of a fine network of collagen fibrils. Adjacent leaves merged or were closely linked by bridging fibrils and were arranged according to the split-line pattern. The surface layer (lamina splendens) was morphologically distinct. Although ordered, the overall collagen structure was different in each plane (anisotropic) a property described in previous morphological and biophysical studies. As all components of the articular cartilage matrix interact closely, the three-dimensional organisation of collagen is important when considering cartilage function and the processes of cartilage growth, injury and repair.