**6.5 Conclusion**

218 Biomedical Science, Engineering and Technology

Total joint replacement (TJR) has to be considered in patients with radiographic evidence of hip/ knee OA who have refractory pain and disability. Principally, OA occurs less commonly at ankle, elbow, and wrist and thus total joint replacements are less frequent at these sites than at the hip or knee. In the last few years, interest in total knee arthroplasty has resulted in a

The indications for TJR have evolved and are expanding. Currently TJR are offered to patients earlier in the course of the disease as the risks of complications associated with TJR

1. *Condvlar replacements:* The joint surfaces alone are replaced. Ligaments then are needed

2. *Hinge-type prostheses:* In this type the ligaments are sacrificed and stability is provided

This is an anatomically designed replacement for either the medial or the lateral femoral tibial articulation. It is designed to allow 120 degrees of flexion. The *unicondvlar* prosthesis is

The femoral component of the duocondylar prosthesis is similar in shape to that of the unicondylar model except that there is no anterior flange and instead the halves are connected by an anterior cross bar which is countersunk during insertion. Because of its anatomical shape, it is most suitable when deformity, instability, and flexion contracture are

The prosthesis is non-anatomical in that the curvature of the femoral component is of constant radius. The plastic tibial component is in one piece, with two halves connected by an anterior bar. The prosthesis is designed to allow a 90- degree arc of motion. The cruciate

The Guepar is a Vitallium hinge prosthesis (improved over the Young model) which is fully constrained, providing motion in a fixed axis without rotation. Guepar prosthesis was used

Innovation continues to characterize the TJR field. This clinical dilemma has stimulated a search for biomaterials that produce less wear debris and, in turn, cause less osteolysis, attendant bone loss, and implant failure. This is the rationale for several developments, including highly cross-linked polyethylene and ceramic- on-ceramic and metal-on-metal

Advances in tissue engineering and biologic therapy have led to a few limited successes.

in knees with extrerne deformity or instability due to rheumatoid arthritis and OA.

Perhaps the most notable is autologous chondrocyte implantation (ACI).

2. Isolated cartilage defects typically greater than 3 cm2 in size

The selection of a suitable prosthesis is dependent on the type and the indications

proliferation of prosthetic designs, and many different types are now aaialble.

**6.3 Total joint replacements and arthrodesis** 

by the design of the prosthesis itself.

ligaments are preserved. Two sizes are available.

**6.4 Surgical and biologic procedures** 

have reduced dramatically. The prostheses available are:

to provide stability.

used only for cornpartmental OA.

Types of prostheses 1. Unicondylar

2. Duocondylar

not too severe. 3. Geometric

4. Guepar

bearing surfaces.

Indications 1. Age <50 years It is clear from the foregoing that any simple unitary concept about the link between joint damage and symptoms in OA is untenable. We are faced with a complex interaction between local events in the joint, pain sensitisation, the cortical experience of pain, and what people are doing in their everyday lives.

In the absence of effective disease-modifying therapy, many patients with OA progress to advanced joint destruction. Therefore, surgery plays an important role in the management of OA. Advances in biomaterials and tissue engineering will continue to create exciting new opportunities to integrate surgical approaches in OA care.

Fig. 6. Total knee replacement

Fig. 7. **A**, Cartilage defect on femoral condyle. **B**, Cartilage defect treated with autologous cartilage implantation

### **7. References**

220 Biomedical Science, Engineering and Technology

Fig. 6. Total knee replacement

Fig. 7. **A**, Cartilage defect on femoral condyle.

**B**, Cartilage defect treated with autologous cartilage implantation

