Archives of Orthopaedic and Trauma Surgery

, Volume 133, Issue 6, pp 773–780

The use of a structural free iliac crest autograft for the treatment of acetabular fractures

Authors

  • Yun-tong Zhang
    • Department of Orthopaedics, Changhai HospitalSecond Military Medical University
  • Yang Tang
    • Department of Orthopaedics, Changhai HospitalSecond Military Medical University
  • Xue Zhao
    • Department of Orthopaedics, Changhai HospitalSecond Military Medical University
  • Chun-cai Zhang
    • Department of Orthopaedics, Changhai HospitalSecond Military Medical University
    • Department of Orthopaedics, Changhai HospitalSecond Military Medical University
Orthopaedic Surgery

DOI: 10.1007/s00402-013-1736-3

Cite this article as:
Zhang, Y., Tang, Y., Zhao, X. et al. Arch Orthop Trauma Surg (2013) 133: 773. doi:10.1007/s00402-013-1736-3

Abstract

Introduction

Bone and cartilage deficits in the posterior acetabular wall are severe complications resulting from the unsuccessful management or delayed treatment of acetabular fracture. This potentially disastrous condition cannot be treated reliably with the use of reconstruction plates and screws alone. Therefore, this technical report describes a modified anatomical reconstruction method that uses a structural iliac crest autograft and an acetabular tridimensional memory alloy fixation system (ATMFS) to treat late-stage deficits in the posterior wall of the acetabulum. This paper also describes a clinical study of 22 patients with an average of 6.3 years follow-up to evaluate the clinical outcomes of this method.

Methods

Twenty-two patients, who had an acetabular reconstruction between January 2000 and December 2011 that used a structured free iliac crest autograft to treat late-stage bone and cartilage deficits in the posterior acetabular wall were followed annually with clinical and radiographic evaluations. The average age of the patients was 36.4 years at the time of the procedure, and the average time of follow-up was 6.3 years.

Results

None of the patients in this study lost reduction after surgery, and there were no cases of implant failure. Radiographic analysis using Matta’s X-ray evaluation criteria were excellent in eleven cases, good in eight, and fair on three. The Merle D’Aubigné and Postel clinical outcomes at the final follow-up were as follows: seven cases were excellent, ten cases were good, three cases were fair and two cases were poor.

Conclusions

The use of a modified iliac crest grafting and ATMFS fixation, as a biological method to reconstruct the acetabulum anatomically may offer better congruence of the joint surface and may ensure good hip joint stability during early postoperative exercise. The medium to long-term results of this method are encouraging.

Keywords

Structural free iliac crestAutograftAcetabular fractureAcetabular three-dimensional memory fixation system

Introduction

Fracture of the posterior wall of the acetabulum is the most common type of acetabular fracture, accounting for approximately one quarter of all acetabular fractures [1]. Although complete functional recovery after a posterior wall fracture of the acetabulum is uncommon, a successful long-term result can be expected after anatomic reduction and internal fixation of the fracture [1, 2]. However, studies have found that operative treatment of these fractures has produced varying results. The recent reviews have shown that 21–32 % of patients have poor results [35]. In addition, there is up to a 30 % failure rate within 1 year of fixation of posterior wall fractures, even when surgically treated by experienced orthopedic traumatologists [1]. Because a severe complication of unsuccessful management or treatment-delayed cases, late-stage bone and cartilage deficits in the posterior acetabular wall is a disastrous condition that is a huge challenge for orthopedic surgeons. The main treatment method for this condition is a total hip arthroplasty (THA). Because acetabular wall fractures occur predominantly in younger people [6], these patients are typically active and may face premature failure of the arthroplasty, thus requiring numerous revisions later in life. In this paper, we describe the surgical technique and the variations required to maximize the probability of obtaining an anatomic reduction in these surprisingly challenging fractures.

Surgical technique

The goal of acetabular reconstruction with a structural autograft is to obtain a stable construct with the hip center of rotation positioned at the level of the native acetabulum.

Pre-operation

All injuries were evaluated preoperatively with radiographs in the anteroposterior, obturator oblique, and iliac oblique views with two-dimensional computed tomography (CT) and three-dimensional CT reconstruction analysis. Patients received autogenous and heterogeneous blood transfusion, and skeletal traction was applied via the femoral condyles in all patients to obtain joint distraction.

Operation procedures

Approach and exposure

The patient was positioned in the lateral decubitus position and a standard Kocher–Langenbeck posterior approach was used to expose the posterior wall fractures. Because of muscle contraction and the proximal motion of the great trochanter, the short rotators and position of old fractures were identified based on the specific anatomy to avoid damage to the sciatic nerve. In some cases, the great trochanter osteotomy was used to allow better access to a superior (weight bearing dome) fracture fragment.

Reduction

The screws and plates from the former operation, if any, were meticulously removed. The intraoperative findings included severely comminuted, smashed, and deficient posterior walls of the acetabulum. Bone sclerosis and free osteochondral fragments were found in the acetabular fossa. It is important to clean up the residual bone fragments, sclerosing bone, heterotopic ossification and scar tissues around the posterior wall until the fractured surfaces bleed. Traction was applied to the lower limb, and dislocation of the femoral head was reduced.

Anatomical harvesting and reconstruction

The ipsilateral ilium was reamed with an appropriately sized acetabular reamer centered 5-mm away from the anterior superior iliac spine and close to the inner margin of the iliac spine (Fig. 1). The size of the acetabular reamer was selected based on the diameter of the femoral head and the depth of the acetabular fossa (Fig. 2). The acetabulum rim of the defective section was replaced with the outer margin of the iliac spine, which had been reamed to 3–4 mm thickness. The modified ilium crest graft was then cut off and prepared by removing indentations and protrusions. Then, the graft was placed in the deficit and fixed temporarily with two K-wires (Figs. 3, 4).
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Fig. 1

Cadaveric model (The Second Military Medical University Anatomy Laboratory, Shanghai, China) of an acetabular defect. An appropriately sized reamer is being used to sculpt the iliac graft

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Fig. 2

The size of acetabular reamer was selected based on the diameter of the femoral head and the depth of the acetabular fossa

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Fig. 3

The modified ilium

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Fig. 4

Placement of the modified ilium in the deficiency

Application of ATMFS

To completely integrate the graft into the fractured site and achieve a physiological stress distribution, we designed a new method that anatomically reconstructs the acetabulum with an ATMFS internal fixation. This new method has been previously used for the satisfactory treatment of common fractures of the acetabulum [7, 8]. The fixation procedure used in the ATMFS is as follows: 2–4 mm thickness Nitinol plates were used, which were treated to have an one-way shape memory effect with the shape recovery temperature of 33 ± 2 °C. All of the ATMFS devices were cooled in ice water (0–4 °C) to expand the branches and arms before fixation. The fixation point of the implant was determined, and the fragments were fixed to obtain anatomical reduction of the articular surface. At the edge of the acetabulum, we drilled a tunnel at a 10°–15° angle to the posterior acetabular wall in the direction of the anterior inferior part of the posterior column ridge line, ensuring that the tunnel did not penetrate into the joint (Fig. 5). Then, the ATMFS series Ba and Bb, which are specifically designed for posterior wall fractures (Fig. 6), were used for fixation (Fig. 7). Component Bb was rewarmed, and then inserted to a suitable length as based on the length of the tunnel, the posterior fossa hook was then hung on the concave face of Ba or inserted through the drill hole to fix the bones of the anatomical reconstruction of the acetabular posterior wall (Figs. 8, 9).
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Fig. 5

Two holes sized 2–2.5 mm in diameter are drilled with an angle of 10°–l5° to the acetabular cup in the direction of the square region of the posterior wall

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Fig. 6

Series B of ATMFS

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Fig. 7

Fixation of fragments via Ba

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Fig. 8

Holes are drilled for the correct fixation of Bb. The aligning pin of Bb is inserted, and the arched edge used to clasp the edge of the acetabular cup

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Fig. 9

Fixation of fragments via Bb

Postoperative treatment

The operation area was cleaned completely to decrease the incidence of heterotopic ossification. A drainage tube was used for 3 days and removed when the drainage flow within 24 h was <20 ml. Isometric contraction training of the lower limbs was performed immediately after the patient awoke from anesthesia. On the following day, the patients were asked to gradually initiate extension and flexion of the hip while in bed, with gradual increases in the degrees of flexion. All patients were mobilized without weight bearing for 4 weeks. Partial, toe-touch weight bearing with the use of crutches or a walker was then allowed for a period of 3 months. Thereafter, full-weight bearing was allowed. Representative images of the surgical procedure are shown in Fig. 10a–d.
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Fig. 10

ad Autograft procedure during surgery

Clinical series

During the time period from 2000 to 2011, we performed the technique outlined in the previous section on 30 patients with late-stage bone and cartilage deficits in the posterior acetabular wall. The mechanisms of injury included motor vehicle crash, motorcycle crash, and falls. A total of eight patients were lost to follow-up. One patient, who died 4.5 years postoperation was included in the analysis. Therefore, 22 patients, with an average age of 36.4 years (ranging from 18 to 58 years old) at the time of the procedure, were evaluated at an average of 6.3 years postoperatively. None of the patients in this study experienced a loss in reduction after surgery, and there were no cases of implant failure. By an average of 48 days (ranging from 36 to 63 days) post-operation, patients could walk with full-weight bearing. In nine cases, hip function on the injury side was approximately equivalent to that of the normal side after an average of 6.2 months. Radiographic analysis of these cases using Matta’s X-ray evaluation categorized eleven cases as excellent, eight cases as good, and three cases as fair. The Merle D’Aubigné and Postel clinical outcomes at the final follow-up were as follows: seven cases were excellent, ten cases were good, three cases were fair and two cases were poor.

Typical cases

Case 1

A 42-year-old male patient with comminuted posterior wall acetabular fractures was treated using open reduction and internal fixation. However, he experienced gradual shortening of his limb, prompting him to have his hip checked through radiography at 2 months after his initial operation. The imaging showed catastrophic failure of the initial open reduction and internal fixation procedure, which was associated with a subluxation and posterior wall deficit of the acetabulum (Fig. 11a). The hip did not show signs of posttraumatic arthrosis. At 3 months after the initial injury, the reconstruction operation was performed with the use of a structural free iliac crest autograft. At the last follow-up, 2 years after the second surgery, the patient continued to walk pain free, and the hip range of motion was 80 % that of the normal side. The D’Aubigné and Postel’s clinical outcome evaluation was scored as excellent. The X-rays showed that more than 50 % of the joint space existed, and the femoral head was mostly congruent with the acetabulum. Although subchondral cysts and minimal signs of arthritis were observed in the femoral head and acetabulum, no evidence of collapse or necrosis was found in either the femoral or acetabular subchondral bone, which indicates a good radiologic result according to the criteria developed by Matta (Fig. 11b–d).
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Fig. 11

A 42-year-old male patient with comminuted posterior wall acetabular fractures was treated using open reduction and internal fixation. The imaging showed catastrophic failure of the initial open reduction and internal fixation procedure, which was associated with a subluxation and posterior wall deficit of the acetabulum (a). At 3 months after the initial injury, the reconstruction operation was performed with the use of a structural-free iliac crest autograft. The X-rays showed that more than 50 % of the joint space existed, and the femoral head was mostly congruent with the acetabulum. Although subchondral cysts and minimal signs of arthritis were observed in the femoral head and acetabulum, no evidence of collapse or necrosis was found in either the femoral or acetabular subchondral bone, which indicates a good radiologic result according to the criteria developed by Matta (bd)

Case 2

A 40-year-old male presented with subluxation, obsolete fracture and severe heterotopic ossification of the right hip joint at 4 months and 15 days after the primary operation (Fig. 12a). The anatomical reconstruction following the surgical resection of the heterotopic ossification was performed with the use of a structural free iliac crest autograft. At the last follow-up, 5 years after the second surgery, the patient could walk by himself, and the function of the injured joint was similar to the normal side. Matta’s X-ray evaluation was scored as good (Fig. 12b–c), and D’Aubigné and Postel’s clinical outcome evaluation was scored as excellent.
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Fig. 12

A 40-year-old male presented with subluxation, obsolete fracture and severe heterotopic ossification of the right hip joint at 4 months and 15 days after the primary operation (a). The anatomical reconstruction following the surgical resection of the heterotopic ossification was performed with the use of a structural-free iliac crest autograft. At the last follow-up, 5 years after the second surgery, Matta’s X-ray evaluation was scored as good (bc)

Discussion

The treatment principles for displaced posterior wall fractures of the acetabulum, include early anatomic reduction of the articular surface and stable fixation to allow immediate postoperative exercise [15]. However, the treatment of acetabular fractures that have major segmental acetabular defects or a severely comminuted and impacted posterior wall remains a difficult surgical challenge. The medical community has reached a consensus that the surgery should aim for anatomical reduction of the hip joint surface, especially in the weight bearing area [1, 2, 4]. The goal of surgical treatment of posterior wall fractures is stabilize the hip by restoring the normal shape of the acetabulum and restoring the normal pressure distribution within the joint by anatomic reduction of the articular surface. The integrity and stability of the anatomical reconstruction of the acetabulum are equally important for a successful outcome, and the stress distribution of articular surface should be as close as possible to the physiological state [9]. Bone autografts, especially those using the iliac crest, are often used for acetabular fractures that are combined with mass deficiency or marked impaction and comminution [10, 11]. However, we have not found any related research that focused on anatomical reconstruction. Olson et al. [12] measured the distribution of the contact area and pressure between the acetabulum and the femoral head in cadaveric pelvis samples in three different conditions: intact, with an operatively created fracture of the posterior wall, and after anatomical reduction and fixation. This study demonstrated the marked alteration in the mechanics of load transmission across the hip after a fracture of the posterior wall of the acetabulum and is consistent with the clinical observations that failure of the acute anatomical reduction in the posterior wall of the acetabulum predisposes the hip joint to osteoarthritis. This abnormal state of mechanical loading can remarkably raise the incidence rate of traumatic arthritis. In addition, instead of surface contact, the direct contact of the articular surfaces may cause necrosis of the femoral head. The key factors for surgical success, include maintaining the viability of the fracture fragments and the femoral head. An anatomically reconstructed acetabulum can only be achieved with low incidence of the complications described above.

Instead of traditional reconstruction plates, an ATMFS was used as an internal fixation device for posterior wall fractures of the acetabulum. This new device is made with NiTi shape memory alloy, this metal material has many advantages, including shape memory effect, lower elastic modulus, high resistance to abrasion and corrosion, as well as good histocompatibility. Furthermore, the continuous compression provided by this device improves the fixation stability, stanches bleeding of the fracture site and promotes fracture healing. Biomechanical evaluation of the contact area and load distribution of the ATMFS was found to be at levels similar to the intact condition [13].

As commonly observed in other surgical technique studies, our anatomical reconstruction technique has potential risks and limits. Our method is recommended for the significant impaction of posterior acetabular wall fragments and subsequent posterior wall deficits, which are a result of misdiagnosis, delayed treatment, and surgical failure, especially in younger to middle aged persons refusing arthroplasty. After radiologic follow-up in our patients, the reconstruction of the posterior wall did not restore the posterior acetabular wall back to full congruence. Therefore, with extension of the follow-up period, posttraumatic osteoarthritis of the hip may develop and progress earlier in some of the patients, ultimately requiring THA. However, the anatomical reconstruction significantly delayed the eventual THA, and the incorporated graft will provide the bone stock required for the prosthetic socket, which would be of great clinical significance. In addition, this technique is not recommended for patients with primary fractures. In this instance, we favor using conventional osteosynthesis of such comminuted or impacted fractures to generate better results.

Conflict of interest

The authors did not receive grants or outside funding in support of their research for or preparation of this manuscript.

Copyright information

© Springer-Verlag Berlin Heidelberg 2013