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New mother with hip pain

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Source/Disclosures


Source:
Bayram S, et al. J Bone Joint Surg Am. 2020;doi:10.2106/JBJS.19.00988.


Disclosures:
Liporace, Romanelli and Tang report no relevant financial disclosures.


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A 22-year-old woman presented to the orthopedic clinic with worsening left hip pain, fatigue and inability to keep up with her 2-year-old child.

She reported her birth was complicated by breech delivery with later “hip issues” as a child. Throughout her life, the patient lived with an obvious leg length discrepancy (LLD) without use of a shoe lift, but managed with a relatively sedentary lifestyle. Having recently given birth to her child, she began experiencing significant, severe left hip pain with inability to carry her daughter and fatigue that now caused her to rarely leave her home. The patient had been seen by multiple providers and, failing conservative treatment, she was referred for surgical intervention.

Mark E. Cinque
Mark E. Cinque
Filippo F. Romanelli
Filippo F. Romanelli

The patient had no past medical history, no previous surgical history and did not take any medications. On physical examination, she had an obvious clinical left LLD of three finger breadths when assessed at the medial malleoli. She retained full range of motion (ROM) of her left hip with flexion to 120°, external rotation of 70° and internal rotation of 30°, which was comparable to her right side. She demonstrated 4/5 strength to resisted hip flexion and abduction but, otherwise, had full motor strength. She was able to heel and toe walk.

Radiographic evaluation revealed a left hip Crowe grade 4 dysplasia with a superiorly migrated femoral head with a 6-cm LLD and signs of acetabular dysplasia with absent sourcil and shallow walls (Figure 1).

reoperative anteroposterior (AP) radiograph of the pelvis demonstrating a left hip Crowe grade 4 dysplasia with superiorly migrated femoral head with a 6-cm LLD
1. A preoperative anteroposterior (AP) radiograph of the pelvis demonstrating a left hip Crowe grade 4 dysplasia with superiorly migrated femoral head with a 6-cm LLD is shown.

Source: Filippo F. Romanelli, DO, MBA

A lengthy preoperative discussion was had with the patient and family to review expectations, as well as the potential risks and complications of surgical intervention. The patient was given time for consideration and requested to proceed with surgery at her follow-up visit.

What are the best next steps in management of this patient?

See answer below.

Left THR with subtrochanteric shortening osteotomy

The patient was indicated for a left total hip replacement with a subtrochanteric shortening osteotomy to safely restore her native hip center and avoid over-traction of the sciatic nerve.

The likely residual postoperative LLD was addressed along with the initial need for shoe lift. The potential for a future internal limb lengthening procedure utilizing a NuVasive intramedullary magnetic expansile nail to restore equal leg lengths was also discussed.

Details of surgery

A posterior approach was utilized with lateral positioning on a radiolucent table in the event fluoroscopy was required. Dissection was carried down to the iliotibial band, which was incised with careful attention to identify the proximal migration of the femur. The gluteus maximus fibers were separated to allow for appropriate visualization of the proximal femur. The gluteus maximus tendon insertion was released to obtain proximal femur visualization for subtrochanteric osteotomy and femoral mobilization.

The short external rotators and piriformis tendons were tagged and tenotomized. The sciatic nerve was dissected and visualized at the level of the quadratus femoris to assess tension throughout the procedure. The hip capsule was identified and incised in T-shaped fashion. Mobilization of the femoral head from the pseudocapsule was performed. A large inferior capsular release was performed and the psoas tendon was released to further improve mobilization. The femoral head was then exposed as it was already dislocated and the femoral neck was cut. The hypertrophic capsular tissue was excised and the foveal remnant was used to identify the cotyloid fossa to establish the true anatomic hip center. The superior aspect of the obturator foramen, as well as the ischial tuberosity, was identified as secondary references prior to reaming the new hip center. Sequential reaming starting with a 36-mm reamer was performed in appropriate inclination and version. A 42-mm acetabular cup was impacted and two 6.5-mm screws were placed for additional fixation and the liner was placed.

Osteotomy site preparation

Next, the femur was addressed. A ruler was used to determine the length of the subtrochanteric osteotomy needed based on the preoperative plan and intraoperative findings. Using the tip of the greater trochanter as representation of the center of the femoral head, the distance to the center of the acetabulum was confirmed to be 6 cm. Preparation of the osteotomy site was performed by elevation and retraction of the vastus lateralis anteriorly. Bovie marks were placed on either end of the osteotomy site prior to osteotomy to ensure appropriate rotation after fixation. A 6-cm transverse subtrochanteric osteotomy was performed starting at a level 1-cm distal to the lesser trochanter. A 2.5-mm drill bit was used to create drill holes bicortically to establish means for controlled osteotomy with an osteotome. The 6-cm clamshelled fragments were left as biological grafts with special attention made to maintaining viability by retaining perfusion with muscular attachments. Both ends of the newly osteotomized femur were temporally reduced and held in place with large Vaber clamps while maintaining appropriate rotation. Subsequent reaming of the femoral stem was performed and trials placed to establish appropriate length and offset. A standard offset size 15-mm x 225-mm Wagner stem was then impacted while maintaining appropriate femoral rotation and implant version (Figure 2).

A saw bone model of a femur illustrating each step of the SSO procedure
2. A saw bone model of a femur illustrating each step of the SSO procedure is shown. A bovie was used to mark each end of the osteotomy site (a). A 6-cm transverse osteotomy was then performed 1 cm distal to the lesser trochanter (b). A 2.5-mm drill bit was used to create drill holes bicortically to allow for controlled osteotomy with osteotome (c). The 6-cm clamshelled fragments were used as autografts and kept viable by retaining perfusion with muscular attachments (d, e). Both ends of the newly osteotomized femur were reduced using large Vaber clamps while maintaining appropriate rotation (f, g). Subsequent reaming and stem implant trials were placed to establish appropriate length and offset. A standard offset size 15 mm x 225 mm Wagner stem was chosen and then impacted into the femoral canal while maintaining appropriate femoral rotation and implant version (h, i).

The osteotomized bone with surrounding bone block graft was fixed utilizing four 1.7-mm tensioned cables. Additional fixation was provided with a 3.5-mm custom-contoured reconstruction plate with the appropriate screw fixation within the femoral shaft and greater trochanter. Once fixation was established, trialing of the appropriate head was performed and a modular, dual-mobility, 22-mm + 3 ceramic head was placed (Figure 3).

Postoperative AP (a) and lateral (b) radiographs demonstrating a left THR in place of the osteotomized femur
3. Postoperative AP (a) and lateral (b) radiographs demonstrating a left THR in place of the osteotomized femur stabilized with four 1.7-mm tensioned cables and a 3.5-mm custom-contoured reconstruction plate are shown.

The patient was taken through a full ROM and found to be stable. The short external rotators and posterior capsule were closed through bone tunnels in the greater trochanter. The patient was to be kept toe-touch weight-bearing with posterior hip precautions for 6 weeks. A postoperative leg length study was performed to establish her LLD for custom shoe lifts (Figure 4).

postoperative scanogram demonstrating maintenance of the preoperative 6-cm LLD is shown
4. A postoperative scanogram demonstrating maintenance of the preoperative 6-cm LLD is shown.

Discussion

A subtrochanteric shortening osteotomy (SSO) is a safe, effective and reliable option to restore the anatomic hip center in patients with Crowe 4 hip dislocations. Depending on severity, this option does not necessarily restore LLD but has been shown to greatly improve functional scores in this patient population. The decision to pursue shortening osteotomy is made by a combination of careful preoperative planning based on LLD and intraoperative evaluation of the patient’s soft tissue tension both before and after any necessary releases, with special attention to tension of the sciatic nerve. The SSO can be combined with de-rotation to correct any variance in femoral version, which is commonly encountered in this patient population. Studies have found both the diagnosis of hip dysplasia and leg lengthening during THR to be independent factors associated with sciatic nerve palsy. The reported safe increase in leg length during THR has ranged from 0.6 cm to 4.3 cm in various studies, with recently reported mean safe limits to be 3% of femoral length and 1.7% relative to anterior superior iliac spine to medial malleolus distance, which was only 1.42 cm in this case. Currently, no absolute maximum value of lengthening has been established for this specific patient population as the causes for nerve palsy are multifactorial and not due solely to lengthening, but also to the difficulty of intervention, retractor placement, intraoperative technique, as well as other patient factors.

Several osteotomy techniques have been studied to address Crowe 4 hip dysplasia, which include the greater trochanter osteotomy, lesser trochanter osteotomy and subtrochanteric osteotomy. The subtrochanteric osteotomy can be performed either via transverse (which is the simplest), oblique, double chevron (V-shaped), step-cut (Z-shaped) or sigmoid approaches. The transverse osteotomy is still the most reported in the literature as it is the simplest, least technically challenging and least time-consuming while being effective and reliable with satisfactory patient-reported outcomes. Currently, no difference has been found in union rates, reoperations or patient-reported outcomes based on osteotomy type, although a heterogeneous mode of fixation and stem types have been studied. With respect to the transverse osteotomy, healing times have varied from 2 months to 6 months with reported nonunion rates ranging from 0% to 20%. To mitigate the risks of nonunion, we recommend minimizing the soft tissue stripping at the osteotomy site, avoiding saw thermal necrosis by use of an osteotome and providing stable fixation with long, splined stems with plate augmentation, in addition to tensioned cables (Figure 3).

Possible complications

While studies have reported excellent results, patients with Crowe 4 hip dysplasia present unique challenges and may still be at risk for postoperative complications, which include intraoperative femur fracture, nonunion of the osteotomy, hip dislocation and nerve palsy, either secondary to direct iatrogenic injury or excessive lengthening. In patients with severe LLD that persists, such as the patient who presented with a 6-cm LLD, patients may undergo contralateral THR to restore leg lengths (when indicated) or lengthening of the operative limb to correct any residual shortening. Our patient will continue with a custom shoe lift until radiographic union is achieved. Once healed, we plan to proceed with intramedullary distraction osteogenesis via a magnetic expandable nail. This distraction osteogenesis will be achieved by performing a distal femoral osteotomy about 7.5 cm proximal to Blumensaat’s line and insertion of a retrograde NuVasive Freedom nail secured at either side of the osteotomy site. Magnetic distraction of the remaining 6 cm of leg length will then be performed by lengthening 0.8 mm daily starting on postoperative day 7 until appropriate leg lengths are achieved.

Key points

SSO is an effective treatment option that has shown to greatly improve functional scores in patients with Crowe 4 hip dislocation by safely restoring anatomic hip center while avoiding overtraction of the sciatic nerve.

The SSO can be combined with de-rotation to correct femoral version and avoid impingement, which is commonly encountered in this patient population.

The decision to pursue a shortening osteotomy is made by a combination of careful preoperative planning based on LLD and intraoperative evaluation of the patient’s soft tissue tension both before and after any necessary releases with special attention on tension of the sciatic nerve.

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