Larsen III–V destruction with significant clinical symptoms. Progressive bone destruction, particularly in the acetabular area (acetabular roof necrosis, protrusion, cysts, etc.).
Principles for determining treatment
Treatment is initiated earlier in rheumatoid patients than in arthritis patients in order to avoid simultaneous progressive destruction in multiple joints (see also indications for knee prosthesis, Chapter 7.2).
Progressive bone destruction in a rapidly progressing course: do not wait until the acetabular fossa is destroyed. Regular radiographic monitoring is recommended because progression can be relatively asymptomatic compared with the overall level of disease.
Specific disclosures for patient consent
Prosthetic loosening; dislocation. Bone fracture; perforation.
Instruments
Prosthesis set from the manufacturer of choice.
Position
The position will be according to the chosen approach (anterior, anterolateral, dorsal, minimally invasive). The superiority of one approach over another has not been established in rheumatoid patients. It is therefore recommended to use the approach that one is most familiar with. The use of a special hip table is recommended.
Fig. 8.1 A severely obese rheumatoid patient. The bone is frequently very osteoporotic. Traction is placed on the extremity, and the hook is adjusted accordingly. An extensive synovectomy is usually necessary.Fig. 8.2 (a,b) Exposure of the acetabular lamina interna. Overlying osteophytes may need to be removed with an osteotome. Reaming is initially directed primarily toward the center and then continued in the direction of the acetabular roof. The lamina interna must be reamed under direct visualization because it is very vulnerable if the bone is osteoporotic.Fig. 8.3 An uncemented press-fit acetabular cup can be anchored even in severely osteoporotic bone. Acetabular impaction bone grafting using the femoral head is also frequently performed. The femoral cancellous bone is placed centrally and compacted with a trial cup.Fig. 8.4 Severely osteoporotic bone requires a cemented socket or an additional acetabular reinforcement cage.Fig. 8.5 (a,b) Necrosis of the acetabular roof requires careful reaming (also reverse reaming for severely osteoporotic bone). Cancellous bone from the femoral head is used to perform an acetabuloplasty. In poor-quality bone, a rigid fixation is achieved by impacting the press-fit acetabulum and adding screws. An alternative is an acetabular cage with cemented cup.Fig. 8.6 (a,b) For severe protrusion, a wedge of bone is resected from the femoral head and stripped of its cortex. If the bone wedge is too hard, it is weakened by radial incisions made with an osteotome. The graft is placed in the center, impacted with a trial cup, and adjusted so that it lies entirely within the acetabular space.Fig. 8.7 (a–c) Severe acetabular protrusion in rheumatoid arthritis. A cancellous bone wedge is taken from the femoral head and used to reconstruct the acetabular cup.Fig. 8.8 (a,b) Severe acetabular protrusion in ankylosing spondylitis. A bone wedge is removed from the femoral head and used to replace the acetabular floor. The cup is additionally secured with a screw. There is pronounced coxa vara. The center of rotation is realigned by lateralizing the femoral shaft.Fig. 8.9 (a,b) Significant protrusion requires an acetabular reinforcement cage and a cup fixed with cement.Fig. 8.10 The type of reinforcement cage is dependent upon the amount of protrusion and how reconstructible it is.Fig. 8.11 (a,b) Because the bone is often significantly more fragile than suggested on the preoperative radiograph, the soft tissue on the shaft is very carefully exposed and released.Fig. 8.12 The potential for subluxation and impingement is thoroughly assessed in all directions of movement. In highly inflammatory forms, the periarticular soft tissues are often noticeably elongated.Fig. 8.13 Long-standing rheumatoid arthritis. Severe osteoporosis.Fig. 8.14 Intraoperative shaft fracture.Fig. 8.15 (a,b) Surgical internal fixation.Fig. 8.16 (a,b) Trochanter fracture 8 weeks postoperatively in a patient with long-standing rheumatoid arthritis and long-term cortisone therapy.
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