Conservative Hip Surgery Case Title: Subcapital Realignment in Unstable SCFE
Demographics
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Age: 12 years Sex: Female BMI: 19
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Relevant Past Medical History
Principal pathologies: Inconspicuous anamnesis Previous surgical procedures: None Medication: None
Other: None
History of presenting complaint: Left groin pain beginning during light physical activities such as running in the gym. The pain increased during the following hours to the extent that walking became impossible. Hospital admission on the same day, clinical findings looked like a hip fracture
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Clinical Examination
Symptoms: Spontaneous leg position in the pronounced external rotation. Severe groin pain with any movement
Range of motion: Not tested because of pain
Specific tests: No specific tests
Main disability: Pain and inability to stand on the leg or walk
Neurovascular evaluation: No neurovascular abnormality
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Preoperative Radiological
Assessment/Imaging (Fig. 1.17)
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Preoperative Planning
Diagnosis: Unstable SCFE (Fig. 1.17).
Possible treatment options: (1) Pinning in situ and Imhauser osteotomy later when needed. (2) Gentle closed reduction and pinning. (3) Subcapital realignment with Dunn technique. (4) Subcapital realignment with surgical dislocation and extended retinacular flap technique.
Chosen treatment method: Subcapital realignment with surgical dislocation and extended retinacular flap technique (Fig. 1.18).
Selection of implants if applicable and rational: 2–3 fully threaded 3 mm pins.
Expected difficulties: Difficulties to execute the trochanteric osteotomy due to the limited internal rotation. Disconnected epiphysis.
Strategies to overcome difficulties: When a fixed external rotation does not allow correct positioning of the saw plate, the osteotomy may have to be performed with an osteotome placed under the vastus lateralis and advanced proximally. With the diagnosis of an unstable slip, emergency surgery is indicated. If an experienced surgeon is not available, prophylactic in situ fixation of the epiphysis should be performed, and the definitive surgery be postponed.
Templating: Possibly measuring intraosseous pin length on the healthy opposite hip.
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Fig. 1.17 The left hip with severe slip, diagnosed as unstable
Extended retinacular flap
Extended retinacular flap Retinaculum Capsule
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Fig. 1.18 Sketch of the extended retinacular flap
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Surgical Note
Patient’s position: Lateral decubitus position with holders placed against the lower lumbar spine and the symphysis. Skin preparation and draping for a free leg.
Type of anesthesia: General or conductive anesthesia.
Surgical approach: Surgical dislocation approach as described in “Case Title: Surgical Hip Dislocation as the First Step for Revision of Instability from Arthroscopy” (Ganz R, Leunig M) (Sect. 1.5).
Main steps: As mentioned above, in severe slips with limited internal rotation, placement of the oscillating saw for correct trochanteric osteotomy can be rather difficult; occasionally, the osteotomy has to be performed with an osteotome cutting from distal to proximal. The mobilized trochanter is then gradually retracted anteriorly and superiorly. Further flexion and external rotation of the leg facilitate visualization of the anterior, superior, and posterosuperior capsule. In the case of SCFE, a possible hemar-throsis is documented and also whether it is under pressure. After capsulotomy, the epi-metaphyseal stability is tested. When disconnection is obvious or even in doubt, 2–3 Kirschner wires are inserted from the trochanteric area to temporarily stabilize the head or to increase the stability. No attempt to reduce the epiphysis is made at this moment. Rupture of the anterior periosteum near the epiphysis is frequent; progression of the rupture into the retinaculum is rare and should be documented. When accessible, the epiphyseal cartilage is perforated with a 2 mm drill; bleeding from the drill hole indicates perfusion of the epiphysis. Only now the head is subluxated; the round ligament is cut with curved scissors and the head carefully and gradually dislocated placing the leg into a sterile bag on the opposite side of the table. Placing a large Hohmann retractor around the posteroinferior rim allows inspection of the entire acetabulum. Damage to the anterosuperior labrum and cartilage can come from impacting or inclusive impingement, which can be observed with
flexion and internal rotation of the reduced head. The need for acetabular debridement or refixation of a ruptured labrum is rare. The next step is the subperiosteal dissection of the posterolateral retinaculum containing the necessary vessels for a sufficient perfusion of the epiphysis; the flap length from insertion at the head-neck junction to the level of the lesser trochanter is necessary to avoid overstretching of the vessels during manipulations for the osteotomy. It starts with piecemeal resection of the stable trochanter down to the level of the posterior neck applying a strictly subperiosteal execution. All external rotators are part of this flap. More proximally, the periosteum of the neck is longitudinally incised at the anterior border of the retinaculum. Both parts together are further dissected from the bone toward the posterior neck using a sharp periosteal elevator. While the preparation of the posterolateral retinaculum is best performed with the head reduced, dissection of the posteromedial retinaculum including Weitbrecht’s ligament with the vessel providing perfusion of the inferomedial epiphysis is easier with the dislocated head. The end result is a posterior half tube of the periosteum allowing circumferential access to the neck without interfering with the perfusion of the epiphysis [16].
Reconstruction techniques: Before any attempt
is made to reorient the epiphysis, a swab is placed into the acetabular socket, to avoid accidental reposition of the mobile epiphysis. It is only now that Kirschner wires fixing the epiphysis are removed. During this process, the epiphysis is manually preserved from being rotated. If necessary, further mobilization of the epiphysis is achieved with a curved osteotome introduced in the anteromedial metaphysis at the cartilage border and slightly propagated. Few parallel cuts may be necessary before levering attempts with the osteotome together with the careful external rotation of the leg result in increasing mobilization of the epiphysis. During this process, the complete posterior detachment of the periosteal tube from the neck must be secured. Further external rotation allows full presentation of the stump of the neck, while the epiphysis connected
to the retinacular fold remains posteriorly. The posterior neck surface is now checked for callus formation. It has to be emphasized that such posterior bone apposition has been found even in cases of unstable slips without clinical warning signs, and it was also present in the case illustrated here. Such bone formation can be seen or palpated and has to be resected flash to the normal neck surface to prevent adverse tension in the retinaculum during anatomic epiphyseal alignment. Before attempting epiphyseal repositioning, debris of the growth plate has to be curetted, while the epiphysis is manually fixed to avoid adverse rotation. This is often resulting in visible bleeding from the epiphyseal bone. During manual positioning of the epiphysis on the metaphysis, the tension of the retinaculum is constantly tested, and if found too high, the neck has to be shortened millimeter by millimeter. Care has to be taken that the posterolateral retinaculum is unfolded before realignment of the epiphysis. While the position of the epiphysis is manually secured, an optimal offset all around the neck is visually examined. The first fixation is achieved with a retrograde wire inserted through the fovea capitis. Before reduction of the head into the socket, the swab has to be pulled from the acetabulum. The optimal spatial positioning of the epiphysis is controlled with fluoroscopy. Thereafter fixation is completed with two additional fully threaded wires, inserted from the subtrochanteric level of the lateral cortex and spaced out in the epiphysis. One may now repeat the drill holes to check the perfusion. Retinacula and joint capsule are readapted without any tension. The trochanteric fragment is refixed with two 3.5 mm screws, slightly distal to the original position. Before trochanteric fixation, a careful test for joint stability can give information about the amount of distal advancement of the trochanter (Figs. 1.19 and 1.20).
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Intraoperative Challenges
Challenges and solutions: Many patients with SCFE are overweight; for sufficient exposure of the proximal femur, a marked distal and proximal
extension of skin and subcutaneous tissue incision may become necessary. The gluteus maximus may act as a hammock limiting dislocation of the femoral head. Separation of the fibrous insertion on the femur can create the necessary muscle release to allow the dislocation. Dislocation may become impossible when external rotation is limited due to extra-articular impingement between the basis of the grater trochanter and posterior acetabular wall. Trimming of the posterior trochanteric bone being part of the execution of the retinacular flap may be brought forward to increase external rotation. Although the retinaculum was not damaged at direct visualization, one or several drill holes may not show discharge of blood. Nevertheless, surgery has to be continued as planned. The perfusion test may become positive after reduction of the epiphysis as seen in several cases [26]. Even when the perfusion test after reduction remains negative, surgery should be completed; the patient has to be informed about the increased risk of necrosis but also that uneventful outcome has been reported [26, 27].
Unanticipated problems and solution: (1)
Rarely the posterolateral retinaculum is found to be almost completely disrupted. (2) Severe acetabular cartilage damage may become visible at dislocation and inspection of the joint, especially when a chronic slip becomes unstable. The head may migrate into the cartilage defect after anatomic correction. (3) Joint instability due to excessive shortening of the neck.
Thorough description of decision making, including the reason for the final decision: (1) One should omit to perform a dislocation in order to keep the ligamentum teres as additional blood supply intact. The posterior callus may be resected through the retinacular rupture although this is a delicate maneuver. An alternative would be to continue the procedure with in situ pinning and to wait for the further evolution of the case. (2) When such a cartilage damage was not anticipated, e.g., by a preoperative MRI, any surgery to re-center the head has to be discussed first with the patient. Further imaging including abduction/adduction views may help in the decision making. In the case of a high femoral anteversion, a subtrochanteric derotation
would be in line, while an intertrochanteric correction is rather excluded in the presence of pins in the trochanteric area. A very powerful method to regain joint stability is a periacetabular osteotomy [28]. (3) To overcome this problem, the levering bone has to be removed and sufficient distal advancement of the greater trochanter be performed. Attempts to stabilize the joint with purse-string sutures of the capsule should be omitted. Additional fixation in a plaster may be discussed.
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Postoperative Radiographs
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Fig. 1.19 Anteroposterior projection five years after surgery showing the anatomic alignment of the epiphysis without signs of necrosis
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Fig. 1.20 Lateral view after five years with correct orientation of the vital epiphysis
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Postoperative Management
Chemoprophylaxis and anticoagulant treatment period: The patient received routine antibiosis for 24 h. No anticoagulation treatment was given at this young age.
Gait/limb loading until full loading: Non-weight bearing with two elbow crutches for eight weeks followed by gradually increasing the load. Unrestricted walking after three months.
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Follow-Up and Complications
The presented patient had no postoperative complications. In an earlier series, three patients needed revision surgery for metal failure (1); there was no head necrosis related to the surgery in stable and intraoperatively verified unstable slips (2).
Scoring if available: At 5-year follow-up, the HHS was 100.
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Discussion
Advantages of the applied method: Anatomic realignment at the level of the deformity with low risk of surgically induced epiphyseal necrosis.
Disadvantages of the method: Dissection of the extended retinacular flap and execution of the subcapital realignment are technically demanding. It can hardly be learned from textbooks or video clips. The best way is to assist an expert on several occasions and do the first cases under his supervision.
Alternative evidence-based techniques for the case: The classic Dunn procedure can lead to similar results. However, it is less safe due to the limited subperiosteal exposure of the neck and the fact that the epiphysis remains in the socket during manipulations. Both aspects increase the
risk of overstretching or rupture of the retinaculum.
Why is the chosen technique better for this case? In unstable SCFE, closed reduction has a high incidence of necrosis. The reason is the bone apposition in the posterior neck. Such bone formation may be present even in cases without warning signs [26], as it was seen in this case. The more the reduction will be anatomic, the more the retinaculum will be deviated and stretched over this bone, regardless whether the reduction was performed gently or not. With the open procedure as described, the incriminating bone can be removed before, and the retinacular tension can be controlled during epiphyseal reduction.
Indications and contraindications for your technique: The procedure is indicated for stable slips with an angle of 30° or more and all unstable slips. The procedure is not indicated when the physis is closing or already closed.
Learning curve and how to manage complications: As outlined above the learning curve is steep when the procedure is studied in a center with a reasonable volume of cases, and technique-related complications can be reduced when the first cases are executed under supervision.
Level of evidence concerning the superiority of this method against others: Despite the high technical demand, the procedure has gained increasing interest in the literature [29].
