We performed a database review the patients with Perthes disease treated with hip salvage procedures at our tertiary referral center between January 2003 and January 2009. Eighteen consecutive patients with Perthes disease were identified: three patients had primary periacetabular osteotomies to improve femoral head coverage coupled with a simultaneous osteochondroplasty of the femoral head through an anterior arthrotomy. Fifteen subjects were treated with surgical dislocation, osteochondroplasty of the femoral head-neck junction, fourteen of patients also had a relative neck lengthening via trochanteric advancement. Two of these patients underwent a staged surgical dislocation and osteochondroplasty with trochanteric advancement followed by a periacetabular osteotomy to correct acetabular deficiency8
. We elected to retrospectively analyze the presentation, surgical treatment and clinical and radiographic outcomes of the fourteen patients that underwent both SDO and trochanteric advancement. All fourteen hips met the inclusion criteria which also included availability of pre and postoperative radiographs, histories and physical exams, and postoperative followup of six months or greater.
Of the fourteen patients who underwent trochanteric advancements via surgical dislocation, there were four female and ten male patients, with an average age of 19.6 years old (range 14–28). Prospectively collected clinical data on all patients, including presenting medical history, pre and postoperative Harris Hip Scores, clinical, operative, and radiographic findings were reviewed retrospectively. Patients typically had signs and symptoms of impingement as well as discomfort with activity.
Radiographs demonstrated a shortened femoral neck (coxa breva) in varus (coxa vara) as well as a flat, mushroom shaped head (coxa magna), and a relative overgrowth of the trochanter with a decreased or negative center-trochanteric distance (CTD)7, 9
. () In addition to dysmorphic proximal femurs, hips with Perthes disease sometimes also have shallow acetabuli, up-sloping sourcil (acetabular roof) with varying degrees of anterior and/or lateral deficiency. ()
Anteroposterior radiographs pre and post surgical dislocation and relative femoral neck lengthening demonstrating improved head-neck offset and center trochanteric distance.
FIGURE 2 Anteroposterior radiographs pre (left) and post surgical dislocation and relative femoral neck lengthening (center) andpost staged periacetabular osteotomy (right). Post surgical dislocation radiograph demonstrates improved head-neck offset andcenter (more ...)
Preoperative radiographs were evaluated for standard measurements including acetabular index, anterior and lateral center edge angles, and acetabular angle of Sharp. The center of the femoral head used for measuring radiographic measurements such as center-edge angles and CTD was determined by the intersecting of the longest and shortest diameters of the femoral head “egg.” () The modified classification system of Stulberg et al was used: Stulberg class-II femoral heads fit within 2 mm of a circle on both anteroposterior and frog-leg lateral radiographs; class-III were aspherical by more than 2 mm on either view; class-IV femoral head as one with at least 1 cm of flattening of the weight-bearing articular surface10
. Radiographs were evaluated for crossover sign11–13
, signifying acetabular retroversion, and posterior wall sign, signifying posterior acetabular deficiency11, 12
FIGURE 3 Anteroposterior hip radiographs. Preoperative radiograph on the left demonstrates a method for determining acetabular coverage when measuring center edge angles in hips with aspherical femoral heads associated with Perthes disease. Postoperative radiograph (more ...)
Additionally, we measured pre and postoperative CTD,7
which is recorded in millimeters, indicating if the tip of the trochanter is above or below the level of the center of the femoral head, rather than the articulo-trochanteric distance (ATD)14, 15
which merely notes whether the tip of the trochanter is positive or negative, above or below the femoral head’s center. () Omeroğlu et al. described pathological CTD as distances greater than +7 millimeters and less than −17 millimeters. We were not aware of this classification or recommended range for normal prior to the surgeries reported in this study7
Surgical Dislocation and Osteochondroplasty Technique
We utilize a lateral skin incision that was carried down through the subcutaneous fat and through the fascia lata using sharp dissection. The vastus lateralis was sharply elevated off the anterior proximal femur. The interval posteriorly between the medius and the posterior edge of the trochanter was developed. A trochanteric osteotomy was performed using a inch oscillating saw and completed with a straight osteotome. The gluteus minimus and medius were left attached to the superior aspect of the trochanteric fragment and the vastus lateralis remained attached to the inferolateral aspect as described by Ganz et al5
. A Wagner retractor was placed over the anterior rim of the acetabulum to facilitate exposure. The interval between the piriformis and the short external rotators was left intact. With external rotation of the hip, the entire anterior hip capsule extending from the piriformis posteriorly to the anterior-inferior portion of the hip capsule was exposed.
A Z-shaped capsulotomy was then performed and sutures are placed in the flap corners. At this point, range of motion assessed including flexion as well as internal and external rotation which helps identify areas of impingement16
. After transecting the ligamentum teres, the femoral head was dislocated without difficulty.
Special attention was given to identifying femoral head-neck morphology including offset, as well as severity and location of damage to the femoral and acetabular articular cartilage and the acetabular labrum. Osteochondritis dissecans (OCD) lesions of the femoral head were diagnosed on preoperative radiographs and magnetic resonance arthrography when present and confirmed intraoperatively. The lesions were treated with osteochondral autograft from the anterolateral aspect of asphericity of the femoral head that is removed with osteotomes to improve femoral head morphology. After the OCD lesion was debrided and burred to bleeding bone, the autograft was shaped with rongeurs and osteotomes to size and press fit into the lesion, attempting to make the cartilage surface flush with the adjacent articular surface. An absorbable pin (Arthrex Trim-It Drill Pin™, 2mm × 100mm) was utilized in one hip due to concern regarding autograft stability.
When Outerbridge III and IV acetabular cartilage damage or labral lesions were encountered the labrum was sharply transected from the affected rim with a long handled knife, leaving the anterior and posterior labrum attached like a “bucket-handle” as described by Espinosa et al17
. The labrum was then debrided back to non-degenerated labrum and the cartilage lesions were treated with resection of the acetabular rim back to normal cartilage. A burr was used to create a bleeding cancellous bed along the extra-articular acetabular rim allowing for reattachment of the labrum via suture anchors. The femoral head-neck junction was debrided with the use of osteotomes and a high-speed burr to improve offset. The femoral head was returned to the acetabulum and correction of impingement was confirmed.
Using towel clips for traction, the trochanteric fragment was advanced distally and inspected for position using fluoroscopy. When a satisfactory increase in the CTD was accomplished, a high-speed bur was used to create a smooth bleeding bone bed along the lateral surface of the proximal femur for stable positioning of the distalized greater trochanter. Attention should be made to limit the thickness of the trochanteric fragment and observe the degree trochanteric prominence after distalization. Too much offset has been shown to increase the risk for trochanteric bursitis and therefore debulking the trochanteric fragment in some cases may be necessary18
K-wires were used for preliminary trochanteric fixation. After fluoroscopic confirmation of satisfactory distalization, two fully threaded, large-fragment cortical lag screws were placed. After distalization of the trochanteric fragment, there was usually a remaining spike or bulge of the previous medial aspect of the stable greater trochanter still attached to the superior base of the femoral neck. A combination of osteotomes, rongeurs, and a high-speed bur were used to contour the newly formed anterior and superior femoral neck-trochanter transition. A Freer elevator was used to elevate the retinaculum off the femoral neck during contouring to protect the blood supply. The capsule was then repaired without tension using interrupted absorbable suture, before closing the fascia, subcutaneous, and skin layers.
Occasionally, soft-tissue tension of the posterior retinaculum and soft tissues was noted when there was scarring from previous surgeries or need for greater distalization. In this situation, pedicalization of the posterior trochanteric fragment may be advisable19
. This was accomplished by dissecting the vascular pedicle posteriorly before performing the initial trochanteric osteotomy. A small osteotomy of the posterior greater trochanter may be performed to allow the retinaculum to fall posteriorly and distally without tension on the retinacular vessels. The osteotomized posterior trochanteric fragment can then be debrided with a rongeur.
We compared the age, and preoperative and postoperative HHS of subgroups using Student’s t test. All of the collected data were analyzed using a commercially available software package (FileMaker® Pro 7.0, FileMaker, Inc, Santa Clara, CA; and Microsoft® Excel®, Microsoft Corp, Redmond, WA).