Orthopedics - Oleksa A.P. 2006

Congenital and Acquired Deformities of the Lower Extremity
Congenital and Acquired Deformities of the Hip
Stable and Unstable Epiphysiolysis

The traditional Classification of Slipped capital femoral epiphysis (SCFE) is based on the duration of clinical symptoms and radiological findings.

Kallio et al. (Kallio P.E., Peterson D.C., Foster B., 1993) argue that SCFE can be classified in greater detail based on objective sonographic data. The authors suggest that the presence of joint effusion indicates epiphyseal instability or recent disease progression. At the same time, remodeling serves as a sign of chronicity.

Acute SCFE, characterized by marked synovitis, represents instability in their view, which justifies gentle closed reduction or traction. In cases of chronic progressive slippage (without synovitis), improvement cannot be achieved through closed reduction.

Kallio and co-authors state that acute-on-chronic SCFE (manifested by intra-articular synovitis and femoral HEAD remodeling) can be partially corrected using Conservative Methods.

According to these authors, the presence of intra-articular synovitis is an indication for surgical stabilization of the epiphysis.

Loder et al. (Loder R.T., Richards B.S., Foster B., 1993) also propose a classification system, dividing SCFE into stable and unstable categories based on Clinical presentation. They note that patients with unstable slips are unable to bear any weight on the hip joint, whereas patients in the stable group can be managed conservatively or without specific Treatment.

These authors report a favorable prognosis in patients with stable SCFE (96% of patients) compared to 47% of those with unstable SCFE. A lower incidence of avascular necrosis is also observed (0% in stable versus 50% in unstable SCFE).

Based on their observations, There is a significant difference in prognosis between patients classified according to their system and those classified using Traditional Methods. The number of patients treated by the authors with internal fixation did not correlate with the degree of slippage when using preoperative traction, the degree of reduction, or the number of pins used for fixation.

Degree of slippage. The extent of epiphyseal displacement can be objectively calculated as the percentage of epiphyseal offset relative to the diameter of the femoral neck.

If the displacement is 1/3 or less of the neck diameter, it is classified as grade I slip (mild displacement).

If the displacement reaches 2/3 of the neck diameter, it is considered grade II SCFE (moderate displacement).

When the displacement exceeds 2/3 of the metaphyseal diameter, it is classified as grade III (complete displacement).

Another METHOD FOR DETERMINING slippage, described by Southwick (Southwick W.O., 1967), involves drawing a line along the physeal borders of the epiphysis and a perpendicular to that line. A line is then drawn along the long axis of the femoral diaphysis, and the angle between this axis and the perpendicular is measured (Fig. 161).

A complete displacement (grade III) occurs when the angle exceeds 60°, moderate slippage is between 30° and 60°, and mild slippage is 30° or less. Normally, an angular deviation of up to 10° is considered acceptable.

Class="center">

Fig. 161. Determination of the degree of slipped capital femoral epiphysis according to Southwick W.O. (1967): a — angle in the anteroposterior projection in normal and SCFE conditions, b — angle in the lateral projection in normal and SCFE conditions.

Treatment. Treatment should begin as soon as the Diagnosis is established.

Children are not permitted any weight-bearing regardless of the degree of slippage, even in stable SCFE. These patients are advised to use crutches or a wheelchair and should be hospitalized as soon as possible. It is important to evaluate children to rule out previously undiagnosed endocrinopathy, which dictates the management strategy.

There are also varying opinions regarding traction. Traction is useful in acutely painful hips, which may be associated with flexion-adductor contracture and synovitis.

Significant improvement from traction is also observed in acute slips; furthermore, data indicate that traction reduces the incidence of avascular necrosis (Crawford A.H., 1988; Casey E.H., Hamilton H.W., Bobechko W., 1972). However, the specific protocols for traction are not yet fully standardized (Fig. 162).

Bryant traction is generally sufficient. In acute slips (grade II chronic SCFE), a weight of approximately 3 kg is applied to improve the condition and achieve a grade I slip within 24 hours.

Patients with stable slips who have a full range of motion may not require traction. This also applies to patients with minimal displacement who can undergo pin fixation directly.

Forcible manipulation of displaced epiphyses is contraindicated due to the high risk of avascular Necrosis of the femoral head.

Similarly, any form of manipulation is contraindicated in chronic slips.

Kallio et al. demonstrated that joint effusion detected by ultrasound in acute or acute-on-chronic SCFE indicates instability. In such cases, they recommend improving the physeal alignment through gentle reduction or traction.

Kallio et al. (1993) suggest that these acute slips, identified according to their criteria, can be partially corrected. However, attempts to exceed this threshold to achieve ideal results in chronic slips significantly increase the risk of avascular necrosis.

Reduction of an acute slip is performed on an orthopaedic table under general anesthesia. Any intraoperative manipulations that may damage the posterior vascular network of the femoral epiphysis generally lead to catastrophic consequences.

A significant percentage (25%) of avascular necrosis cases are precisely caused by the reduction of acute slips—a critical factor to consider when striving for perfect anatomical reduction (Boyer D.W., Mickelson M.R., Ponsetti I.V., 1981).

Pin Fixation. Most grade I and II epiphysiolyses, as well as pre-epiphysiolyses, are treated with percutaneous pin fixation. This method serves to prevent further slippage and accelerates physeal closure.

Fig. 162. Radiographic outcomes of acute slipped capital femoral epiphysis reduction according to Bruks: a - before reduction, b - after reduction.

In the past, multiple-pin bundles were used; however, each pin insertion carries a risk of damaging the articular Cartilage.

The incidence of chondrolysis decreases significantly when specialized pins or screws (Fig. 164) are placed in the central portion of the head, at least 5 mm away from the articular surface (Morrisy R.T., 1990; Riley P.M., Weiner D.S., Gillespie R., 1990).

It is essential that the fixation devices do not reach the superolateral angle of the epiphysis due to the risk of segmental necrosis caused by arterial injury (Brodetti A., 1960). Fixation is performed under fluoroscopic control in two projections to ensure the screw is centrally positioned (Fig. 163).

Cannulated screws are inserted over guide wires, allowing for minimally invasive, atraumatic placement and providing reliable epiphyseal stability.

The ideal screw placement is illustrated in Fig. 164.

Epiphyseal growth disturbances may occur following pin fixation, but these can be avoided by using a cannulated screw or a Steinmann pin (Laplaza E.D., Burke S.W., 1995).

In stable slips, the lateral projection in the "frog-leg" position is optimal for determining the insertion angle of the guide pin. After the pin is inserted, full range of motion in the joint is checked to confirm that the joint has not been breached by the pin.

Care must be taken to ensure that the screw is not inserted too distally into the cortical bone of the metaphysis.

Complications during and after implant insertion are unpredictable due to The properties of the metal; titanium implants must not be reused under any circumstances.

Following surgery, the child uses crutches for 4-6 weeks until synovitis resolves. In stable slipped capital femoral epiphysis, crutches can be used for a short period, whereas in unstable cases, some authors recommend non-weight-bearing for 6-12 weeks.

Fig. 163. Radiographs of the femoral neck and head fixed with a thin screw for grade I slipped capital femoral epiphysis.

Fig. 164. Extra-articular corrective osteotomy at the Base of the femoral neck (a), wedge (b), fixation of bone fragments with screws (c).

The outcomes of single-screw fixation for slipped capital femoral epiphysis demonstrate the lowest incidence of chondrolysis and avascular necrosis (Ward W.T., Steko Y., Wood K.B., 1992).

Bone graft epiphysiodesis.

This Procedure is performed to avoid complications associated with pin insertion and to accelerate physeal closure, particularly in cases of acute or unstable slips.

The surgery is performed via an anterolateral or lateral approach. A bone tunnel is drilled from the subtrochanteric region toward the epiphysis. A cortico-cancellous graft, harvested from the iliac crest, is impacted into the tunnel. This procedure was proposed by Howorth (Howorth B., 1957), who reported no postoperative complications (such as chondrolysis or avascular necrosis) in 200 operated patients. The favorable outcomes of this technique were subsequently confirmed by Herndon and Heyman (Herndom C.N., Heyman C.R., 1963).

However, recent reports by several authors indicate dissatisfaction with the results of this operation. For instance, Ward and Wood (Ward W.T., Wood K.V., 1990) described postoperative complications and abandoned the procedure. Rao and Crawford (Rao S.B., Crawford A.H., 1996) reported heterotopic ossification in 44 out of 64 patients treated in this manner. Due to these and other complications, they also abandoned the technique. The authors now consider bone graft epiphysiodesis to be a salvage procedure, reserving it for unstable slips and supplementing it with internal fixation.

A positive aspect of the surgery is the reduction of the anterolateral angle, which sometimes restricts medial hip rotation.

Osteotomies.

Some authors attempt to correct angular deformities using corrective osteotomies. Varus deformity, posterior head tilt, and lateral rotation lead to excessive femoral neck retroversion and alter joint anatomy and biomechanics, which contributes to The Development of osteoarthritis.

Transcervical femoral osteotomies. Intracapsular corrections are anatomically logical and well-founded, but it is difficult to imagine performing such an osteotomy without damaging the Blood supply and causing avascular necrosis.

Surgery via a direct transtrochanteric approach was described by Dunn and Angel (Dunn D.M., Angel Y.C., 1978). The Joint Capsule was incised in a T-shape near the acetabular limbus and along the axis of the neck in the area of vascular branching. The posterior vascularized wall of the synovial membrane on the neck was gently elevated subperiosteally, ensuring vascular connection with the epiphysis. Next, the distal part of the neck was resected, the fragments were repositioned, and fixed with pins. This reduced the tension of the capsule and vessels along the posterior surface.

Fish (Fish Y.B., 1994) modified this procedure by introducing an anterior closing wedge, but this operation is risky and is therefore no longer used.

The incidence of avascular necrosis following transcervical femoral osteotomies is nearly 25 %.

Extracapsular osteotomies of the femoral neck base. This procedure was described by Ward (Ward W.T. et al., 1992) as more reliable and not complicated by avascular necrosis (Fig. 164).

Biplanar osteotomy is performed along a line just outside the joint capsule from the greater to the lesser trochanter via an anterolateral approach. The surgical plan is based on a careful study of radiographs in two projections. Because the wedge osteotomy is extracapsular, the vessels are not injured. The base of the wedge should not be wider than 2 cm; otherwise, adequate neck length will not be preserved, and increased anteversion may occur.

These same authors note that difficulties arise when inserting pins if an attempt is made to correct a deformity by more than 55°.

Screw fixation following osteotomy is easier to perform than fixation with multiple pins in cases of moderate and severe slippage. Typically, a single screw is passed through the epiphysis (if it is not yet closed), while the fragments, following wedge removal, are fixed with two shorter screws. As noted, the screw should not be directed toward the superior pole of the femoral head. The authors state that following osteotomy in unilateral cases, a limb length discrepancy between the operated and healthy leg may occur. If it exceeds 1.5 cm, they recommend epiphysiodesis of the distal femoral epiphysis on the healthy side. These authors do not use the combination of multiple pins and a screw described previously.

Intertrochanteric osteotomy was proposed by Newman (Newman P.N., 1960) to correct biomechanical abnormalities in severe (displaced) slipped capital femoral epiphysis. This procedure does not carry the risk of avascular necrosis, but it may lead to significant femoral shortening.

Southwick (Southwick W.O., 1967) improved surgical planning. Using radiographs in two projections, he calculated the correction angle to restore the normal neck-shaft angle during surgery.

Newman and Southwick perform flexion-valgus and internal rotation osteotomy to correct posterior tilt, lateral rotation, and Varus deformity of the Femur.

One must keep in mind the possibility of total hip arthroplasty in adults following this procedure for coxarthrosis, as well as the high incidence of chondrolysis resulting from these surgeries.

Chondrolysis can occur as a complication both after surgery and following pin fixation. According to these authors, chondrolysis is more common in Black children, and the exact cause remains unknown. Fewer cases of chondrolysis are observed when screws are used.

Avascular necrosis occurs less frequently now that forceful reduction has been abandoned. It is also absent in stable slipped capital femoral epiphysis and occurs frequently (47 %) in unstable cases (Loder R.T. et al., 1993). It is possible that significant slippage compresses the vascular network, which affects the incidence of osteonecrosis.

It is also believed that preoperative traction reduces The rate of avascular necrosis, which is more commonly seen after closed reduction under general anesthesia on the operating table (Green N. et al., 1991).

Magnetic Resonance imaging (MRI) is the most effective diagnostic method for detecting early osteonecrosis.

If avascular necrosis develops, any hardware must be removed before head compression occurs, and children should be restricted from weight-bearing until Bone Structure remodeling is complete.