Treating post-traumatic hypertrophic non-union with Precice limb lengthening system

Diagnosis

Post-traumatic hypertrophic non-union of the right femur with a 5.5 cm limb length discrepancy

Surgeons

Salah Alsaifi, M.D. and Ahmed Abdelaziz, M.D. of Al-Razi Orthopedic Hospital Kuwait

Details

A 24-year-old male involved in a motor vehicle accident in October 2016. This resulted in bilateral femoral fractures and a posterior wall acetabular fracture that were treated at another hospital. Patient presented to me with a hypertrophic non-union of the right femur, complained of midthigh pain and had a noticeable limp due to a 5.5 cm post-traumatic limb length discrepancy.

Brief clinical history

  • October 2016: Previous history of bilateral femur fractures and right posterior wall acetabular fracture after involvement (Fig. 1) in a motor vehicle accident (MVA)
  • Patient in a medically induced coma for one month in ICU after MVA
  • November 2016: Bilateral femur and right acetabular ORIF
  • Right femur fixed with locked plate (Fig. 2)
  • June 2017: Diagnosed with hardware failure and non-union of the right femur (Fig. 3)
  • July 2017: Revised with interlocking nail (Fig. 4)
  • June 2018: Diagnosed with hardware failure and hypertrophic non-union of the right femur (Figs. 5a, 5b)
  • December 2018: Revised with large diameter interlocking nail (Fig. 6)
  • January 2019: Patient was referred to Lower Limb Deformity Clinic because of short limping gait due to limb length discrepancy

Physical examination

On physical examination, he was found to have a short limping gait. He was able to walk with both feet in a plantigrade position, but had a tendency to flex his left knee in stance. This disappeared and he was able to walk comfortably with a 5 cm shoe lift on the right side. He had a normal foot progression angle in both limbs.

In an upright standing position, a pelvic tilt was noted. However, the tilt disappeared when blocks were placed under the right foot to level the pelvis (Figs. 7a, 7b). In the standing position, observation from the front determined that his limb alignment appeared symmetric and he did not have noticeable genu varum or genu valgum deformity. Examination from behind while standing showed symmetric knee heights with pelvic tilt to right side. His spine was straight in an upright sitting position. Supine exam revealed a positive Galeazzi test (left knee higher than the right knee). Both knees were stable to ligamentous exam. There were no joint contractures noted in hip, knee or ankle. In the prone position, he had symmetric internal and external rotation of both hips and a normal thigh foot angle on both sides. He had intact sensation andnormal muscle strength in both lower extremities.

Radiographic analysis

Standing full-length, bilateral lower extremity radiographs were taken. A 3.5 cm block under the left foot did not fully correct his limb lengths. An additional 2 cm of discrepancy was present creating a total discrepancy of 5.5 cm. Analysis of the individual segments reveals the tibias to be symmetric in length, but the right femur is 5.5 cm shorter than the left femur (Fig. 8a). The mechanical axis is symmetrical and slightly medial to neutral in both knees. The mechanical lateral distal femoral angle measurements show a 2° difference between the 2 sides. The medial proximal tibial angle measurements show a 1° difference between the two sides (Fig. 8b).

Radiographic analysis (cont.)

The X-ray of the fracture site (right femur) showed a hypertrophic non-union with intramedullary locking nail fixed with one locking screw proximally, two locking screws distally and residual broken screw from previous hardware failure (Figs. 9a, 9b).

Treatment strategy

The decision making process was as follows:

  1. The right femur was chosen to lengthen because the majority of the leg length discrepancy was from the femur.
  2. After discussing the pros and cons of lengthening techniques using external fixator devices versus the intramedullary lengthening nail, the patient chose the intramedullary lengthening nail.
  3. Since the right femur still had an antegrade interlocking nail, it was decided to first remove the intramedullary nail and lengthen with a straight antegrade Precice nail.
  4. Based on the previous interlocking nail entry point and angulation, a piriforms entry antegrade straight nail was selected.
  5. Given the non-union of the right femur, the Precice nail will need to be pre-distracted with a fast distractor.
  6. The optimal implant length was determined to be 300 mm and the available implant was 275 mm, so the implant was pre-distracted 25 mm (Figs. 10a–10c).
  7. Since the limb length discrepancy was 55 mm, the 275 mm Precice nail had adequate stroke to achieve the lengthening objective.

In case of incomplete healing at the non-union fracture site, the Precice nail will be used, after complete consolidation of newly formed regenerate bone at the osteotomy site, to compress the hypertrophic non-union site in order to induce healing.

Surgical planning

  1. Since the femur was the segment chosen for lengthening, calibrated A/P radiographs of the right femur were obtained with metal ball (diameter is 25 mm) and metal wire (length is 275 mm) with the same length of Precice nail directly over the lateral skin of the right thigh at the same level (Fig. 11a).
  2. Calibrated lateral radiographs of the right femur were taken with metal ball (diameter is 25 mm) and metal rods directly over the anterior skin of the right thigh at the same level (Fig. 11b).
  3. On the A/P view, the length of the nail (300 mm) was determined to pass the old fracture site with enough length to provide adequate stability (Fig. 11).
  4. On the A/P view, the diameter of the nail was determined. It is recommended to over-ream 2 mm to safely insert the nail. Therefore, this additional 2 mm should be taken into account when determining the nail diameter. Planning determined that a 12.5 mm Precice nail would be optimal (Fig. 11a).
  5. On the lateral view, the proposed diameter of the nail was double-checked to make sure it would fit safely in both planes. The soft tissue distance was measured at the level of the magnet to confirm adequate tissue gap between the implant and ERC (Fig. 11b).
  6. The proposed osteotomy site is detected on the A/P view. To confirm that at least 5 cm of the thick portion of the nail remains in the distal segment throughout lengthening (for maximum stability), the osteotomy should not be within 13.5 cm of the distal tip of the nail [13.5 cm is 5.5 cm (amount of desired lengthening) plus 5 cm (thick portion of nail) plus 3 cm (male portion of nail extending out of female portion of nail)]. To avoid compromising the proximal interlocking screw location, the osteotomy should not be within 6 cm of the proximal end of the nail. The area between the proximal and distal osteotomy limits is the safe osteotomy zone (Fig. 12). The osteotomy level chosen is just above the callus area and in the safe zone.

Intraoperative

  1. The patient was placed in a supine position on a radiolucent table.
  2. The existing nail and locking screws were removed.
  3. The osteotomy level was identified using intraoperative imaging and preoperative planning.
  4. Vent holes were placed at the proposed osteotomy site.
  5. A ball tipped guide wire was placed through the entry hole at the piriformis fossa.
  6. Gradual reaming over a ball tipped guide wire was performed in 0.5 mm increments from 10–14.5 mm. The reaming allows bone graft to spill out of the vent holes around the planned osteotomy site and reaming to the non-united site will help improve healing.
  7. The nail was inserted to the level of the vent holes and the osteotomy was completed. The nail was then passed into the distal bone segment.
  8. Proximal screws were placed through the guide arm.
  9. Distal locking screws were placed using free hand technique.
  10. Nail function was tested in the operating room and 1 mm lengthening was performed.
  11. The location of the magnet was marked on the skin with a skin marker.

Postoperative course

  1. The patient required narcotic pain medication during the first two days postoperatively.
  2. He started gait training in physical therapy on postoperative day one. He was allowed right leg non-weight bearing mobilization with axillary crutches.
  3. Patient performed an at home program of strengthening and range of motion exercises to keep knee extension full and knee flexion to 90°.
  4. On postoperative day ten, he started distraction at 0.75 mm/day with three separate 0.25 mm treatments using the ERC.
  5. Weekly follow-up appointments to check health of regenerate formation (Fig. 8), joint alignment, amount of length gained and hip/knee range of motion until target lengthening goal of 5.5 cm was achieved.
  6. At the end of the distraction phase (11 weeks) the patient was able to maintain 0–30° right knee range of motion.
  7. He advanced to full weight bearing with crutches (120 days postoperatively).
  8. He advanced to full weight bearing without crutches (150 days postoperatively).
  9. The patient returned to many activities without restriction following his six month postoperative evaluation (Fig. 13).

Results

Target lengthening (5.5 cm) was achieved after 74 days of lengthening, complete consolidation for newly formed bone regenerate was achieved at 180 days postoperatively and complete union at the old fracture site was achieved 180 days postoperatively (Fig. 14). Compression at the original fracture site was not needed to achieve union.

Discussion

In addition to internally lengthening bone through distraction osteogenesis, the Precice nail can be used to treat nonunions by:

  1. reaming the intramedullary canal for nail insertion,
  2. gradual distraction osteogenesis (increase local growth factors),
  3. a new osteotomy site near the non-union site (increase blood supply), and
  4. option to compress non-union site.


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