Surgical procedure

Preoperative planning was based on computed tomography-assisted, three dimensional software (ZedHip, LEXI, Tokyo, Japan). After induction of general anesthesia, 1 g of tranexamic acid was intravenously injected before skin incision. Traction DAA for THA was performed with the patient in a supine position, lying on a novel mobile traction table, ~As You Walk ~ LECURE ® (Surgical Alliance, Tokyo, Japan) (Fig. 1). This table can be set up with a standard orthopedic surgical table, and can hold the leg in hip flexion/extension, internal/external rotation, adduction/abduction, or traction, distraction, or compression (Fig. 2). A non-scrubbed and non-sterile assistant handled the traction table. The table provides wide exposure of the proximal femur and the acetabulum both with direct visualization and fluoroscopy. The leather boot is designed to fit the foot and ankle snugly with a double locking bandage mechanism to avoid slipping off the foot. From the superior anterior iliac spine, Heuter’s interval between the tensor fascia lata and sartorius muscle is palpated. The skin incision runs along the mid-line of the tensor fascia lata. This line links the anterior superior iliac spine and the lateral femoral condyle and is more than one finger’s breadth from Heuter’s interval, avoiding injury of the lateral femoral cutaneous nerve. The incision begins 3 cm proximal from the tip of the greater trochanter and 9 cm distal to the trochanter (12 cm long in total). With fluoroscopy, a vertical line passing though the tip of the greater trochanter is identified and the pelvic tilt is adjusted by symmetry of the obturator foramina, centering the coccyx with the symphysis.

~As You Walk ~ LECURE ®, a novel mobile traction table

Movement of the mobile traction table. This table can hold the leg in hip flexion/extension (a), traction, distraction, or compression (b), internal/external rotation (c), or adduction/abduction (d)

The sheath of the tensor fascia lata is incised longitudinally in the direction of the muscle fibers. The muscle fibers of the tensor fascia lata are intentionally pulled laterally within the sheath by the surgeon’s index finger and relaxed by exposing the intermuscular space toward the anterior superior iliac spine. The deep fascia of the rectus femoris is identified by white tendinous fibers, muscle fibers as red, and fat tissue as yellow (tricolor sign). A wound retractor is utilized without a surgical arm or a sinker to hold the retractor. After hemostasis of the arteriole branch, the deep fascia is incised longitudinally at the boundary of the fat tissue to spare the rectus femoris within the sheath. The femoral head is outlined by two narrow Homann retractors, one at the piriformis fossa and the other at the medial aspect of the femoral neck. The triangle of the anterior capsule is visualized; the medial line is the inferior iliofemoral ligament, the lateral line is the insertion of the vastus lateralis muscle and the capsule, and the superior line is the superior iliofemoral ligament. After capsulectomy, the upper outline of the cervicotrochanteric junction is visualized, then 45° of external rotation makes the lower outline clear, and mild traction causes subluxation. The osteotomy is performed in situ, perpendicular to the anterior inter-trochanteric plane. With traction, the osteotomy site is spontaneously opened and the femoral head can be easily removed. The posterior capsule between the acetabulum and the greater trochanter (ischiofemoral ligament and superior iliofemoral ligament) is resected. A blunt forked retractor is placed at the recess of the posterior wall of the acetabulum.

Femoral preparation is recommended before acetabular reaming (femoral first technique). Elevating the calcar femorale with a blunt hook, a sharp fork retractor is inserted into the posterolateral aspect of the greater trochanter. To avoid a hinge phenomenon of the greater trochanter at the posterior wall of the acetabulum, it is useful to apply internal rotation in the neutral position first, and then to apply elevation and external rotation to 90° to visualize the calcar. The ischiofemoral ligament and the superior iliofemoral ligament need to be detached until sufficient anterior mobilization of the greater trochanter is obtained. The pubofemoral ligament also needs to be detached to obtain sufficient lateral mobilization of the calcar. Hyperextension of 35°, relaxation and compression, and adduction of 10° are applied with the traction table. This relaxation technique prevents excessive stretch of the femoral nerve and also assists femoral exposure. A Z-shaped canal finder (Tanaka Ika, Tokyo, Japan) is an essential tool to identify the axis of the medullary canal and anteversion of the calcar. The entry point of the canal finder is the piriformis fossa, avoiding flexion insertion or perforation of the femur. Varus insertion can be avoided by removing the cancellous bone of the lateral femoral canal with the shoulder of this canal finder. Femoral rasps are inserted sequentially.

Acetabular reaming is performed with a straight holder, avoiding excessive reaming of the anterior and posterior walls of the acetabulum. Fluoroscopy intermittently monitors the height and the depth of the reaming, and the cup position. In severely dysplastic hips, the outline for the reaming is prepared with a round chisel. Cup fixation is press-fit and screw fixation uses two 20 mm screws. Reduction is performed by internal rotation and traction. Alignment of the implant and leg length discrepancy are confirmed with fluoroscopy. Anterior stability is examined by external rotation of 90° with mild traction. The acetabular bone defect is reconstructed with morselized autograft. At closure, no suction drains are applied, the fascia of the tensor is sutured continuously but the skin is not sutured, rather it is coated with an adhesive agent (Dermabond, Ethicon, NJ). A water-proof wound dressing is wrapped with a compressive bandage for a few days to prevent hematoma. Postoperative rehabilitation begins on postoperative day one and the patients are allowed full weight bearing.