DISEASES AND DISORDERS 9. 53 10. Rheumatoid arthritis 59 11. Spondyloarthropathies 69 12. Connective tissue diseases 77 13. Osteoporosis and metabolic bone disease 95 14. Crystal arthropathies 103 15. Paediatric joint disease 109 16. Fractures 119 17. Trauma 127 18. Infection of bones and joints 133 19. Fibromyalgia 139 20. Surgical principles in the treatment of bone and joint disease 143 21. Pre and postoperative care 149 22. Bone tumours/malignancy 155 23. Disorders of the spine 163 24. Sports injuries 173 25. Peripheral nerve lesions 181 26. Soft tissue disorders 185
9 Objectives You should be able to: Define and classify osteoarthritis (OA). List the causes of secondary OA. Outline the pathological processes in the development of OA. Describe the clinical features of OA. Describe the X-ray features of OA. Understand the basic conservative and surgical treatments for OA. Definition (OA) is a non-inflammatory disorder of synovial joints characterized by articular surface wear and formation of new bone (attempts at repair). It is also known as degenerative joint disease and characterized by joint pain, stiffness and swelling of joints. Incidence is the most common joint disease, affecting up to 85% of the population at some time in their lives. It is often asymptomatic and the true prevalence of symptomatic OA in the western world is around 20%. Pathology and aetiology Histologically the weight-bearing cartilage surface degenerates and eventually wears away completely, exposing the subchondral bone, which becomes eburnated (Fig. 9.1). Cysts occur because of microfracture of the articular surface and new bone laid down (sclerosis) in the surrounding bone. Disorganized new bone is produced at the margins of joints (osteophytes) as the disease progresses. In addition to this, the synovial lining becomes thickened and inflamed, often producing excess synovial fluid (an effusion). These changes explain the four cardinal features seen on X-ray of joint space: narrowing, sclerosis, cysts and osteophytes. is described as primary where no underlying cause is found or secondary where there is a clear predisposing factor. Primary osteoarthritis has many aetiological factors but the exact cause is not known. A variety of genetic and environmental factors are implicated in causing osteoarthritis. This type of arthritis is more common in women and increases with age. In secondary osteoarthritis a cause is clearly identified and these are shown in Figure 9.2. Clinical features The presenting complaints of patients with osteoarthritis are variable. The patient is usually systemically well and complains of pain which is usually aching or burning in nature and localized to the joint but may be referred to the joint below. The history is often of gradually increasing, asymmetrical joint pain over several years, the level of which is variable but can be severe. The pain is 53
Early changes Secondary causes of osteoarthritis Synovium inflamed Joint capsule inflamed Fibrillation and fissuring of cartilage Narrowing of joint space Congenital/developmental Developmental dysplasia of the hip Perthes disease Slipped upper femoral epiphysis Acquired Trauma: Fractures involving joint surfaces Fractures causing significant deformity Ligamentous injury causing joint instability Infection septic arthritis Avascular necrosis Inflammatory arthritis, e.g. rheumatoid arthritis Neuropathic Charcot joints Metabolic, e.g. Paget's disease Iatrogenic post-surgery, e.g. meniscectomy Fig. 9.2 Secondary causes of osteoarthritis. Changes secondary to loss of cartilage (Outgrowth of bone) osteophytes worse after activity and relieved by rest, and as the disease progresses night pain can be a feature. Occasionally patients present with rapidly destructive OA, which can mimic a septic or inflammatory arthritis. 54 Subarticular cyst Fig. 9.1 Pathological changes in osteoarthritis. Classically pain in the hip can be referred to the knee. Hyperplasia of synovium Thickening and eburnation of bone Patients can present with only one or multiple joint involvement. Other symptoms include swelling, deformity (bow legs varus knee), stiffness and weakness (usually secondary to wasting). Patients will also complain they are unable to do certain activities, which may be recreational or more basic activities of daily living (for example, patients with severe osteoarthritis of the hip are unable to put on socks or cut their own toenails). Almost any synovial joint can be affected by osteoarthritis, most commonly the knee, hip, hands (often the first carpometacarpal joint), fingers (distal interphalangeal (DIP) joints) but also the spine, shoulder, elbow and wrist (Figs 9.3 and 9.4). The examination begins as the patient enters the room. Look for a limp, use of a stick and how reliant the patient is on relatives for simple tasks such as undressing for examination. Deformity may be obvious but also note previous scars, redness, swelling and wasting of muscles on inspection. Palpate for an effusion, joint line tenderness and crepitus (cracking noise can be heard in severe cases). The range of movement of the particular joint will be diminished and there may be fixed deformity. The joints above and below should be examined.
9 Hips Distal interphalangeal joints First metatarsophalangeal joints Cervical spine Lumbar spine First carpometacarpal joint Knees Diagnosis and investigation In many cases the diagnosis is clear from the history and clinical examination, and apart from a plain X- ray further investigation may be unnecessary. Blood tests may be required to exclude septic or inflammatory arthritis in atypical cases if the treating doctor is not certain of the diagnosis. X-rays will usually show decreased joint space, sclerosis, subchondral cysts and osteophytes (Fig. 9.5). Management There is no cure for osteoarthritis and treatment is aimed at relieving pain and maintaining function. The treatment for osteoarthritis can be conservative or surgical. Fig. 9.3 Joints commonly affected by osteoarthritis. A detailed social history is very important in patients who have osteoarthritis. Ask about occupation, activities of daily living and hobbies. What is their normal mobility? These type of questions help to assess patients quality of life and how their condition affects them. Fig. 9.4 of the hand, showing Herberden s nodes at the distal interphalangeal joints and Bouchard s nodes at the proximal interphalangeal joints (from Haslett C, Chilvers E R, Boon N A et al (eds) 2002 Davidson s principles and practice of medicine, 19th edn. Churchill Livingstone, Edinburgh). Classic features of osteoarthritis include Herberden s nodes of the DIP joint and a Baker s cyst behind the knee. Conservative Initially lifestyle advice including weight loss, regular exercise and avoidance of impact loading activities is given. Non-steroidal antiinflammatory drugs such as diclofenac are good in the early stages providing the patient does not have a history of peptic ulceration. Other regular analgesia such as codeine and paracetamol should be prescribed if required. Physiotherapy improves gait and function of an affected limb, and simple measures such as a walking stick reduce pain on walking. Glucosamine is widely taken by the population at large but the small beneficial effect shown in some studies is probably a placebo effect. Injections of corticosteroids are useful for temporary relief, especially in patients unfit for surgery; however, there is a small risk of infection. New treatments such as hyaluronic 55
A acid derivatives given by injection are expensive and not yet proven. Surgical Surgical treatments for osteoarthritis depend on the age of the patient, the joint involved and the level of pain and disability experienced. This is dealt with in more detail in Chapter 20. The decision to operate can be difficult to make, as all surgery has risks and complications. Surgery may help when the patient says, I cannot cope any longer with the pain. B Varus deformity with medial compartment OA Wedge of bone removed Bone removed Fig. 9.5 Features of osteoarthritis on X-ray: (A) hip; (B) knee. Fig. 9.6 Osteotomy of the knee. Alignment corrected 56
9 Arthroplasty surgery is not risk free and patients should be told that although the pain should improve, the joint will never function like a normal joint. Surgery can also have serious complications including infection and thromboembolism which in a small percentage of patients may be fatal. This must be explained during the consent process. There are five things a surgeon can do to a joint: 1. Debride and washout. This is usually done for osteoarthritis of the knee and gives temporary relief in some patients although there is little evidence to support this. 2. Joint replacement (arthroplasty). This is most commonly of the hip or knee. It gives excellent pain relief in 90% of patients for at least 10 years. 3. Joint fusion. The two sides are removed and fused together. This is most commonly used around the foot and ankle; good pain relief is achieved provided fusion occurs but obviously movement is lost. 4. Joint excision. This is less commonly used nowadays. It is still used occasionally in the first metatarsophalangeal (MTP) joint and where other methods have failed (e.g. hip Girdlestone s procedure). 5. Realignment surgery. Increased load passing through a joint because of a deformity often leads to osteoarthritis. The surgeon can realign the limb by breaking the bone above or below the joint, removing a wedge of bone and correcting the deformity. The most common site for this procedure is the knee. The patient will usually have a varus deformity of the knee (bow legs). The tibia is realigned to redistribute the load more evenly, slowing the progression of osteoarthritis. See Figure 9.6. Further reading Miller M D 2004 Review of orthopaedics, 4th edn. WB Saunders, Philadelphia Solomon L, Warwick D, Nayagan D (eds) 2001 Apley s system of orthopaedics and fractures, 8th edn. Hodder Arnold, London Orthoteers website: http://www.orthoteers.co.uk 57