Septic Arthritis in Children

Fig. 30.1

(a) X-rays and (b) appearance of a child who presented with the residua of ankle septic arthritis and osteomyelitis. (c) A plantigrade foot was salvaged by fusing the distal tibia and fibula to the calcaneus, recognizing that limb lengthening would be required at a later date to treat leg length discrepancy

This section illustrates the principles as applied to the sequelae of septic arthritis of the hip. While many of the strategies described are technically demanding and require specialized training, experience, and equipment, most are commonly performed at the tertiary level in resource poor settings, and a visiting surgeon must assess whether his or her training and experiences are sufficient to tackle these challenging cases. While the long-term outcomes following these salvage procedures have not been well defined, the goals are to provide symptomatic relief and functional improvement and to delay or eliminate the need for interventions such as total joint arthroplasty.

Sequelae of Hip Sepsis

The sequelae of hip sepsis include a wide range of morphologic abnormalities of the proximal femur. Secondary changes in the acetabulum can also occur, either as a result of the infection or in response to altered anatomy of the proximal femur. In addition to direct damage to the articular cartilage and the effects of the host’s inflammatory response, increased intra-capsular pressure may result in avascular necrosis. Growth distrubance may also result in altered proximal femoral anatomy. The risk of a poor outcome is increased if diagnosis and treatment are delayed and if coexisting proximal femoral osteomyelitis is present. Growth disturbances of the femoral head or neck, such as coxa magna (Fig. 30.2a–d), femoral neck pseudoarthrosis (Fig. 30.3a, b), septic dislocation with the femoral head present or absent, or post-septic fusion (Fig. 30.4a–e), may also occur. In infants up to 18 months of age, transphyseal vessels allow metaphyseal osteomyelitis to extend to the epiphysis and the joint explaining some of the head and neck changes. Clinical findings may include pain, instability during ambulation, leg length discrepancy, and loss of motion.

../images/270913_2_En_30_Chapter/270913_2_En_30_Fig2_HTML.png — Fig. 30.2

Sequelae of hip sepsis. (a, b) In addition to proximal femoral varus or valgus deformities and rotational deformities, coxa magna is commonly observed due to hyperemia or AVN, while coxa breva is due to altered growth of the femoral neck. (c) Septic arthritis can be associated with proximal femoral osteomyelitis. (d) Multiple joint sepsis often results in significant limb shortening and joint abnormalities

../images/270913_2_En_30_Chapter/270913_2_En_30_Fig3_HTML.png — Fig. 30.3

(a, b) Pseudoarthrosis of the femoral neck

../images/270913_2_En_30_Chapter/270913_2_En_30_Fig4_HTML.png — Fig. 30.4

A spectrum of abnormalities may complicate septic arthritis of the hip and its treatment, including (a) septic dislocation, (b) destruction of the femoral head with a segment of the femoral neck articulating with the acetabulum, (c) loss of the femoral head and neck without proximal migration, (d) destruction of the head and neck with proximal migration, and (e) spontaneous fusion

The history focuses on the impact of symptoms on activities of daily living, particularly the presence, location, and intensity of pain, and the activities or positions that precipitate or relieve it. The source of pain may be intra-articular from damage to the articular cartilage or impingement or extra-articular due to soft tissue contracture or abductor insufficiency. The physical examination focuses on range of motion, limb alignment and length, and presence of pain when the hip is placed in certain positions. Plain radiographs may be the only imaging available, though arthrography or direct surgical inspection may be required to delineate the status of articular cartilage and the relationship between the proximal femur and the acetabulum (Fig. 30.5a–b).

../images/270913_2_En_30_Chapter/270913_2_En_30_Fig5_HTML.png — Fig. 30.5

(a, b) Arthrography is an excellent way to visualize the anatomy of the proximal femur and acetabulum. In this case there is subluxation with interposed material in the acetabulum, with flattening or an oblong shape to the femoral head. (Courtesy of Premal Naik)

Treatment

Treatment goals are to relieve pain, improve the absolute range of motion or the functional arc of motion, improve abductor mechanics, restore stability, and correct leg length discrepancy. Treatment must be individualized, focusing on symptoms, physical findings, and the pathoanatomic changes in the femoral head and acetabulum.

The classification presented by Forlin et al. is simple and practical and helps plan treatment [1]. The scheme focuses on (1) stability and (2) the degree of destruction of the proximal femur. The four categories are:

IA Femoral head present and reduced
IB Femoral head/neck absent but remaining proximal femur has not migrated superiorly (Fig. 30.4b)
IIA Femoral head present but dislocated (Fig. 30.4a)
IIB Femoral head/neck absent and remaining proximal femur is dislocated or superiorly migrated (Fig. 30.4c)

Forlin et al. identified a better prognosis for hips that were reduced than for hips that were dislocated, whether or not the femoral head was present. Arthrographyms, ultrasound, and CT (with 3-D reconstruction) can each provide valuable information about the shape of the femoral head and its relationship with the acetabulum and, in turn, stability.

For cases in which the femoral head is present and the hip is reduced (Forlin IA), treatments include femoral osteotomies to correct abnormalities in the neck-shaft angle (coxa vara or valga) and/or rotational abnormalities (anteversion or retroversion). Pelvic osteotomies such as Salter, Dega, or Shelf can be used alone or with a femoral procedure to improve coverage. For patients with inadequate abductor mechanics, distal transfer of the greater trochanter may improve abductor function Al-Tayebi studied a number of cases using three dimensional computed tomography and identified a variety morphologic alterations of the femoral head and neck [2]. He recommended osteochondroplasty via a modified anterior iliofemoral approach to address this spectrum of abnormalities [2].

Infants and toddlers in whom the femoral head is present but the hip is dislocated (Forlin IIA) are treated by an exam under anesthesia and an attempt at closed reduction and spica casting. An intraoperative arthrogram may be useful. If a closed reduction is unsuccessful, an open reduction with or without a shortening varus femoral osteotomy and/or pelvic osteotomy is required. Johari et al. found that closed reduction and percutaneous adductor tenotomy were only successful in 9/21 patients, and the remaining patients required a variety of procedures to reduce the hip [3]. Factors associated with poor results included preoperative stiffness, avascular necrosis, and premature fusion of the triradiate cartilage. The authors suggested closed reduction be attempted for all patients under 2 years, with open surgical treatment for those who fail closed reduction or are older than 2 years.

In Forlin IB patients, femoral head/neck absent but remaining proximal femur has not migrated proximally, consider an open reduction and capsulorrhaphy to keep any residual femoral neck reduced in the acetabulum, along with a femoral and/or pelvic osteotomy as needed to enhance stability, recognizing that additional procedures will likely be required. A modified anterior iliofemoral approach facilitates exposure for any additional interventions such as joint debridement, osteochondroplasty, capsulorrhaphy, and femoral or pelvic osteotomy.

Treatment when the femoral head and neck are absent with proximal migration of the residual femur (Forlin IIB) depends on the age of the patient and whether restoration of stability, limb alignment, or lengthening is the goal. For asymptomatic patients options include observation and management of leg length discrepancy with a shoe lift or epiphysiodesis on the opposite side. Symptomatic patients may benefit from greater trochanteric arthroplasty, pelvic support osteotomy, or arthrodesis. The first two are motion-sparing techniques, recognizing that arthrodesis may be undesirable in cultures where hip mobility is required for activities of daily living. Rarely is a total hip arthroplasty available, affordable, or reasonable in adolescents and young adults.

Trochanteric arthroplasty involves debridement of any neck remnants or fibrous tissue in the acetabulum by an iliofemoral approach. The trochanteric apophysis is placed into the acetabulum, and the gluteus medius is advanced and sutured to the lateral aspect of the femur. A varus subtrochanteric osteotomy of the proximal femur may facilitate placing the trochanter into the acetabulum, but there is a risk of nonunion if extensive soft tissue dissection compromises proximal femoral blood supply. An adductor tenotomy or psoas release may be needed to restore motion. Trochanteric arthroplasty can be considered for the infant or young child who is symptomatic and in whom a pelvic support procedure is contraindicated because of rapid loss of correction due to remodeling. Variations of greater trochanteric arthroplasty include a modified Harmon arthroplasty described by Choi et al. [4] and the modified Albee arthroplasty described by Li et al. [5], in which the medial portion of the greater trochanter is angulated into varus via an incomplete osteotomy to reduce the trochanteric cartilage into the acetabulum. A triangular iliac crest graft is wedged into the osteotomy to maintain correction (Fig. 30.6a–e). While the long-term prognosis for trochanteric arthroplasty is guarded, the goal is to relieve symptoms, improve gait mechanics, and delay or eliminate the need for other reconstructive options.