13.2b Juvenile idiopathic arthritis: surgical management

Juvenile idiopathic arthritis (JIA) is classified into three subtypes: systemic onset arthritis (10–20% of patients), typically involving fever and extra-articular manifestations, such as rash and myalgias; oligoarthritis (50–60% of patients) with four or fewer joints affected asymmetrically; and polyarthritis (20–30% of patients) characteristically involving multiple joints symmetrically. These are discussed in greater detail in Chapter 13.2a. The most common presentation to an orthopaedic surgeon is with subtalar arthritis and an associated valgus hindfoot but the most frequently involved joint is the knee.

As the aetiology and pathogenesis of JIA is unknown, treatment is supportive rather than curative, requiring specialist care from a multidisciplinary team. A holistic management plan to restore full function should include a rheumatologist, physiotherapist, occupational therapist, ophthalmologist, orthopaedic surgeon, and a psychologist for support and to ensure the child and their family cope optimally with the demands of JIA, enabling the child to integrate fully with their peer group.

Surgery now has a well-established role in the management of JIA with approximately 10% of children treated by a rheumatology unit requiring open surgical procedures. Short-term management is aimed principally at maintaining function, controlling inflammation, and reducing the resultant joint deformity, and thus in the long term, promoting normal growth and development and encouraging education and rehabilitation. The goal is to use the simplest, safest, and least invasive treatment strategy to maintain a normal lifestyle and to minimize morbidity and hospitalization.

Inflamed, arthritic joints will develop flexion deformities rapidly if managed inappropriately whilst prompt medical management, physiotherapy, and judicious splintage will maintain correct joint position and function. Should contracture occur despite this, the procedures to consider include intra-articular steroid injection, synovectomy, soft tissue release, epiphysiodesis, osteotomy, and arthroplasty. Arthrodesis is rarely indicated, other than in advanced disease of the hand or foot where splintage has failed.

The perioperative management of patients with JIA requires input from a multidisciplinary team. Anaesthesia can be problematic (Box 13.2b.2) due to the small airway, hypoplastic mandible, and stiff or unstable cervical spine and preoperative radiographic evaluation of the cervical spine is essential. Difficult airways may require malleable or fibreoptic intubation, or emergency tracheostomy. Laryngeal masks are useful in patients who cannot be intubated. To reduce the risk of postoperative infection, oral steroids should be stopped on the day of theatre; parenteral therapy is used during the perioperative period until the patient is able to tolerate oral medications.

Disease-associated hypervascularity in combination with disuse, means the bones of a JIA patient can be osteoporotic, especially when corticosteroids have been administered, so intraoperatively the limbs should be handled with care. Often the bones are smaller than normal due to growth retardation but, should JIA start in adolescence, bones may be of normal size with a large medullary cavity secondary to a thin cortical rim.

Postoperative rehabilitation can be hampered by general disease activity or more specifically adjacent joint disease activity. It is crucial to identify signs of JIA in adjacent joints preoperatively, as this will affect the success of the planned operation.

Due to their deleterious side effects, systemic steroids should be avoided where possible. Intra-articular injections of corticosteroid such as triamcinolone hexacetonide, have been shown to be safe and effective at controlling synovitis (see Chapter 13.2a). They provide rapid analgesia and facilitate physiotherapy allowing reduction or withdrawal of systemic therapy and a swifter return to normal activity than with systemic treatment alone. The early and repeated use of steroid injections reduces leg length discrepancy in oligoarthritis and prevents joint contractures. The joint effusion should be aspirated prior to injection and the fluid sent for microbiological analysis.

The post-injection regimen of rest, splintage, and physiotherapy remains controversial and has not been studied prospectively in children. It may be difficult to enforce rest in ambulatory children and whilst physiotherapy is helpful, splintage to prevent contractures is unnecessary given the efficacy of intra-articular steroids.

Outcome studies should be interpreted critically: there is inconsistency in the disease subtype studied and the time spans at which response is measured. In the largest published series to date (almost 1500 joint injections), the median duration of improvement was 74 weeks and the most effective injection was the first injection into a single joint.

The side effects of intra-articular steroid injections in JIA have not been studied prospectively but subcutaneous atrophy is a well-recognized complication. Infection rates following steroid injection are estimated at 1:100 000 with no reported cases of septic arthritis in the paediatric population. Damage to intra-articular structures has not been seen.

Synovectomy is indicated when a persistent synovitis has not responded to medical management, in a joint with well-preserved articular cartilage. Given the high rate of spontaneous remission in children, judging the appropriate timing of surgical intervention can be difficult. Some units recommend waiting up to 18 months provided the joint space is maintained. Synovectomy is traumatic and can lead to a temporary increase in pain and this coupled with an uncooperative child can itself lead to stiffness and contracture. As joint damage is underestimated radiographically, MRI is recommended to assess the articular cartilage accurately prior to synovectomy (Figure 13.2b.1).

Historically, synovectomy was most commonly performed in the wrist and knee. Recently, the trend has been to avoid wrist synovectomy and to concentrate on intensive physiotherapy and appropriate splintage. Should the wrist stiffen, maintaining an appropriate position will preserve function. Synovectomy of the knee is still accepted practice. Arthroscopic or open synovectomy can prevent the development of permanent contractures by relieving pain, conserving range of motion, and preventing articular damage. However, it will not improve range of motion or fixed deformity without associated corrective procedures.

There are few studies comparing open with arthroscopic synovectomy in the JIA patient. Open synovectomy requires a considerable incision and has a significant infection rate, whereas the arthroscopic procedure is less invasive and more accurate allowing early mobilization, preservation of range of motion, and reduced hospitalization. The recurrence rate for arthroscopic synovectomy is high (around 40%) and is more likely in patients who show systemic signs of disease progression. Synovectomy should not be delayed to allow systemic ‘flares’ to settle. The aim of synovectomy should be to lengthen the life span of articular cartilage and to remove pannus as once the articular cartilage is destroyed, articular function cannot be restored (Figure 13.2b.2).

The initial management of a soft tissue contracture should be physiotherapy and splintage. If this fails, soft tissue releases are often used especially for the hips and knees. Prior to release, joint decompression with or without synovectomy should be undertaken in order to reduce intra-articular pressure. Elevated pressure can lead to ischaemia, subluxation, porotic fractures, cartilage necrosis, and subarticular microfracture.

Fixed deformities lead to accelerated articular damage and secondary deformities in the ipsilateral adjacent joints and corresponding contralateral joint. As movement is restored after release, joint congruency and overall joint nutrition is improved. Should disease remission occur simultaneously, healing of the articular cartilage can occur and prevent more radical operations. If, conversely, the disease progresses then the subsequent prosthetic replacement is more straightforward as the soft tissue release has improved joint alignment Anterior hip and posterior knee releases are performed commonly. Hip involvement is the most important factor affecting mobility and independence and the typical deformity is that of fixed flexion and adduction. McCullough recommends the following algorithm:

His colleagues report good short- to medium-term pain relief, improvement in gait, and reduction in fixed deformity with total hip replacement necessary in three of 17 patients at a mean 6.3 years after release.

Knee flexion contractures represent a major cause of disability in JIA patients. Soft tissue release can be considered as long as there is a joint space and the valgus deformity does not exceed 15 degrees. A particularly difficult problem is that of posterior subluxation of the proximal tibia, secondary to anterior cruciate ligament contracture; however, ligament resection still remains controversial. Soft tissue release of the knee is technically demanding and aims to release hamstrings, long head of biceps femoris, and the origin of gastrocnemius if required, correcting the flexion deformity and improving mobility. Intraoperative isolation of the common peroneal nerve is vital to reduce the risk of nerve injury. Good improvements in FFD and pain have been reported.

Limb length inequality develops in JIA as a result of multiple local and systemic factors. Given the propensity for knee involvement in JIA, limb length discrepancy (LLD) most commonly occurs in the lower limb. The distal femoral and proximal tibial physes contribute around 2cm per year to limb length. As a result of the inflammatory process, the arthritic knee is hyperaemic adjacent to the physes causing accelerated growth. With oligoarticular disease, or early onset JIA, the medial and lateral aspects of the physis are usually affected equally, lengthening the limb symmetrically. Leg length can return to normal in 2 years with no intervention, either as the arthritis heals or the contralateral knee becomes involved. In a patient with polyarticular disease, a valgus deformity at the knee is common: this too tends to decrease with age. A LLD less than 2cm tends to be asymptomatic and should be treated conservatively with orthoses. If the LLD is due to a FFD that is not amenable to soft tissue release then osteotomy or physeal arrest is indicated. Examination of the ipsilateral hip and ankle is mandatory to ensure there is no other deformity present.

Temporary or permanent epiphysiodesis at the knee is a safe technique even in the immunocompromised child. In a child with JIA the traditional techniques of growth prediction, such as Greulich and Pyle atlas and the Eastwood and Cole graph, are less reliable due to systemic effects of corticosteroids limiting growth and local hyperaemia stimulating growth. Nevertheless, the aim is to achieve correction at skeletal maturity. This requires careful timing of surgery in addition to rigorous follow-up particularly if a temporary epiphysiodesis technique has been used. The possibility of rebound growth following staple removal or further growth of the arthritic joint must be taken into account.

The main indication for osteotomy is correction of an angular or a rotational deformity. Most commonly a supracondylar femoral osteotomy is undertaken to correct a valgus deformity at the knee. Care should be taken when performing the osteotomy as osteoporosis is common. Internal fixation is often difficult given the porotic nature of the bone and a plaster cast may be required for added stability and to maintain joint position. The plaster cast is usually removed at 1 month to enable early mobilization. Some patients require repeat osteotomies for recurrence of the deformity associated with excessive growth.

As the goal is to preserve range of motion, arthrodesis is rarely performed. However, arthrodesing a deformed wrist in a functional position is beneficial for hand function. This can be achieved by the use of a low profile arthrodesis plate or by intramedullary fixation with a Steinmann pin passed down the third metacarpal via the carpus into the distal radius.

Arthroplasty is reserved for those patients who have irreversible articular damage with associated restriction of movement, deformity, and significant pain. The choice of treatment and the timing may be influenced by the overall pattern of joint involvement (Figure 13.2b.3). Arthroplasty in a patient with JIA requires care pre-, intra-, and post-operatively to ensure that potential pitfalls specific to the patient group are avoided. Other treatments should be pursued prior to arthroplasty and whilst they may only delay prosthetic replacement, improvement in systemic symptoms and increased growth may be vital for the success of an arthroplasty. The survival rate of total hip arthroplasty (THA) and total knee arthroplasty (TKA) improves with increasing patient age. Currently, joint replacements are undertaken for the hip, knee, shoulder, elbow, wrist, and ankle.

In JIA patients, THA has been used successfully, in terms of functional recovery, for 40 years. The main indications for THA in addition to those mentioned earlier are subluxation/dislocation and protrusio acetabuli. THA is usually undertaken once skeletal maturity has been reached. However, an open physis is only a relative contraindication to surgery as the proximal femoral physis only contributes 15% to limb length and is often damaged by JIA. There is a slightly higher rate of acetabular failure with an open triradiate physis and in our opinion THA should be performed when the triradiate is fused (which may be early as a result of JIA). The relationship between diaphyseal expansion of the femur and the longevity of a cemented or uncemented femoral prosthesis in a growing patient is still unknown. JIA patients are protected by their low weight and low activity but still experience significant rates of aseptic loosening. The growing, remodelling skeleton, associated osteopenia and steroid treatment may contribute to early prosthetic loosening. Component wear rates are low in JIA populations because of their low demand.

Should hip and knee arthroplasty be indicated, then the THA should precede the TKA. THA is less painful than TKA and rehabilitation post-THA is possible in the presence of stiff knees. Hip deformity can contribute to knee deformity and correction of the former may suffice. Conservative management of knee contractures are possible with a THA in situ and the best TKA outcomes are seen in patients with strong hip muscles.

In young patients, THA will not usually last a lifetime: the current consensus is, where possible, to use uncemented components. With cemented femoral prostheses, it is difficult to centralize the prosthesis and obtain an adequate cement mantle. Subsequent cement fracture, subsidence, osteolysis, and reduction in bone stock lead to failure. Although cementless stems are technically challenging, careful, gradual reaming and the use of longer modular stems helps preserve bone stock. In early press-fit design stems there was a higher failure rate due to a lack of early fixation. With the advent of porous and hydroxyapatite coating, the results of uncemented femoral components have improved. Despite the characteristics of JIA bone, rapid osteointegration has been demonstrated.

Early to mid-term function is improved in the JIA patient regardless of the fixation method. Postoperatively, function improves more slowly than in patients with other pathologies because of the polyarticular nature of the disease and systemic treatment but both sitting and activities of daily life show marked improvement. In one study, 94% of THA patients were wheelchair bound preoperatively but 88% were still ambulatory at 11-year follow up. Survival at 15 years for cemented THA in JIA is approximately 70% and 90% acetabular and 100% femoral component survival rates for uncemented prostheses have been reported at 13 years.

TKA is indicated in JIA patients with marked functional impairment or disabling pain from advanced joint involvement. As with THA, skeletal immaturity is only a relative contraindication. However, incomplete distal femoral physeal closure can lead to progressive angular deformity and arthroplasty should be delayed in those patients with significant growth potential. Contraindications to arthroplasty include systemic or local knee infection, hyperextension deformity, quadriceps weakness, and Charcot neuropathic arthropathy.

Preoperative physiotherapy and serial casting should be employed to minimize flexion contractures and facilitate the surgery. Postoperative bracing and manipulation to maintain or regain ranges of motion are preferable to increasing the distal femoral excision to accomplish intraoperative correction of deformity. This allows the knee to function more naturally and reduces the propensity to raise the joint line. As little bone as possible should be removed and bone graft used to address bony defects. At the time of TKA, JIA is usually burnt out; however any remaining synovium should be excised. The patella, which is frequently small, deformed, laterally subluxed, and high riding, should be resurfaced and the osteophytes excised.

In the presence of severe flexion contracture or posterior tibial subluxation, the posterior cruciate ligament (PCL) must be sacrificed to achieve optimal soft tissue balancing and alignment. Proponents of the PCL sacrificing prosthesis argue that it allows improved deformity correction, increases joint congruency, and reduces polyethylene wear. However, cruciate retaining prostheses preserve bone stock, allow femoral roll-back, facilitate stair climbing, and absorb shear forces better. There are no long-term studies comparing cruciate retaining or sacrificing prostheses in the JIA patient.

Potential long-term cement failure with component loosening and osteolysis has led to increased interest in uncemented prostheses. As JIA patients are young, uncemented prostheses have obvious benefits; maintenance of bone stock for revision, lack of biological response to polymethylmethacrylate, reduced operating time, no cement extrusion and associated wear debris. There are no long-term results for uncemented TKA and as cement is tolerated better in the knee than the hip, there is less urgency to abandon its use in younger patients.

Radiolucent lines are common and remain a concern: the majority are asymptomatic and their clinical significance remains to be established. Regular and long-term follow-up of this young patient group is essential.

The literature indicates that TKA in JIA patients with severe and disabling knee joint involvement provides predictably good pain relief and functional improvement. Survival rates ranging from 100% at 4 years to 77% at 10 years have been reported.

Shoulder involvement is seen later in the course of systemic or polyarticular JIA, with an incidence of 15% at 15 years. Indications for shoulder arthroplasty are pain, reduced function and joint destruction in patients who have failed more conservative treatments. Significant improvement in joint movement has been reported.

Encouraging results have been reported following total elbow arthroplasty with 87% of joints showing increased function and a reduction in pain at 2 years postoperatively. Indications include destruction of the ulnohumeral joint with gross restriction of movement (<30 degrees) and pain.