Biomechanical analysis of hemipelvic deformation after corticospongious bone graft harvest from the posterior iliac crest

Strategies for large bone defect reconstruction after trauma, infections or tumour excision: a comprehensive review of the literature

Large bone defects resulting from musculoskeletal tumours, infections, or trauma are often unable to heal spontaneously. The challenge for surgeons is to avoid amputation, and provide the best functional outcomes. Allograft, vascularized fibular or iliac graft, hybrid graft, extracorporeal devitalized autograft, distraction osteogenesis, induced-membrane technique, and segmental prostheses are the most common surgical strategies to manage large bone defects. Given its optimal osteogenesis, osteoinduction, osteoconduction, and histocompatibility properties, along with the lower the risk of immunological rejection, autologous graft represents the most common used strategy for reconstruction of bone defects. However, the choice of the best surgical technique is still debated, and no consensus has been reached. The present study investigated the current reconstructive strategies for large bone defect after trauma, infections, or tumour excision, discussed advantages and disadvantages of each technique, debated available techniques and materials, and evaluated complications and new perspectives.

Pelvis weight-bearing ability after minimally invasive stabilizations for periacetabular lesion

Periacetabular metastatic lesions cause debilitating weight-bearing pain and pose a risk of pelvic pathologic fracture. Minimally invasive percutaneous stabilization is an alternative palliative therapy over extensive open reconstructive surgeries. This study aimed to investigate the biomechanical behaviors of three distinct techniques of percutaneous periacetabular stabilization. A total of 20 composite hemipelves custom-made to contain Harrington type III periacetabular lesion based on a patient's computed tomograpy scans were assigned to treatment groups of cementoplasty alone using polymethyl methacrylate (Cement), screw fixation alone using ischial and posterior-to-anterior screws (Screws), cement-augmented screws (Screws&Cement), and a control group (Untreated). All hemipelves were loaded in a mechanical test configuration mimicking a single-legged stance, and failure load, failure deformation, and construct stiffness were determined. In the experiments, Screws&Cement demonstrated the highest yield strength (4711 ± 362 N) and was 12% higher than Cement (4005 ± 304 N, p = 0.019), 125% higher than Screws (2097 ± 359 N, p < 0.0001), and 184% higher than Untreated (1658 ± 254 N, p < 0.0001). No significant difference in yield strength was found between Screws and Untreated. Screws&Cement also demonstrated the highest stiffness (1013 ± 92 N/mm), followed by Cement (893 ± 49 N/mm), and both groups were significantly stiffer than Screws (543 ± 114 N/mm, p < 0.0001) and Untreated (580 ± 91 N/mm, p < 0.0001 for Screws&Cement, and p = 0.0003 for Cement). This study demonstrated that a cement-augmented periacetabular reconstruction is an effective option for percutaneous treatment of Harrington III periacetabular metastatic lesion. The addition of pelvic screws over cementoplasty significantly improved the pelvis load-bearing strength. When large periacetabular lesions are present, augmented screw fixation appears to be the superior choice of treatment.

Harvest of Iliac Crest Autograft Not Associated With Localized Pain

Background

There exists a wide variety of bone grafts, substitutes, and extenders, which are utilized in spinal arthrodesis surgery. While iliac crest autograft is the traditional gold standard for use in spinal arthrodesis, there is considerable discrepancy in the literature regarding its associated complications. Primarily among these is the perception that the procedure is painful and has a high infection rate. The purpose of this study is to determine if patients experience more pain postoperatively on the iliac crest autograft donor side of the pelvis than the contralateral side.

Methods

This study was a retrospective chart analysis of prospectively collected data on 76 patients who underwent elective lumbar arthrodesis with iliac crest autograft performed by one surgeon. The patients filled out a pain diagram with a five-region visual analogue scale, including each iliac crest, at the preoperative and each postoperative visit. Patient-reported pain data at various time points was compared from donor and contralateral sides and analysis included trends over time. Additionally, complications were noted when they occurred. The surgical approach involved a midline skin incision in all patients with epifascial and subperiosteal dissection to the posterior superior iliac spine.

Results

There were no significant differences in reported pain between donor and nondonor side. There was no significant main effect of side of measurement (P = .75) and no significant side by time of measurement interaction effect (P = .95). There was a significant main effect of time of measurement for both sides (P < .001). There were no cases of donor site complications.

Conclusions

Iliac crest harvest and reconstruction utilizing this technique does not result in increased pain on the side of the harvest. This study supports a low morbidity rate for iliac crest autograft harvest as no complications were seen in this series.

Level of Evidence

3.

Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting

BACKGROUND

Iliac crest bone harvesting is a frequently performed surgical procedure widely used to treat bone defects. The objective of this study is to assess the biomechanical quantities related to risk for pelvic fracture after harvesting an autologous bone graft at the anterior iliac crest.

METHODS

Finite element models with a simulated harvest site (sized 15 × 20 mm, 15 × 35 mm, 30 × 20 mm and 30 × 35 mm) in the iliac wing are created. The relevant loading case is when the ipsilateral leg is lifted off the ground. Musculoskeletal analysis is utilized to compute the muscle and joint forces involved in this motion. These forces are used as boundary conditions for the finite element analyses. Bone tissue stress is analyzed.

RESULTS

Critical stress peaks are located between the anterior superior iliac spine (ASIS) and the anterior edge of the harvest site. Irrespective of the graft size, the iliac wing does not show any significant stress peaks with the harvest site being 20 to 25 mm posterior to the ASIS. The harvest area itself inhibits the distribution of the forces applied on the ASIS to extend to the posterior iliac wing. This leads to a lack of stress posterior to the harvest site. A balanced stress distribution with no stress peaks appears when the bone graft is taken below the iliac crest.

CONCLUSION

A harvest site located at least 20 to 25 mm posterior to the ASIS should be preferred to minimize the risk of iliac fatigue fracture.

Iliac wing fracture following graft harvesting from the anterior iliac crest: literature review based on a case report

The morbidity of bone graft harvesting from the iliac crest has been widely discussed in the literature. For some authors, it is considered to be low and for others relatively high. We report on a case of a fracture of the iliac wing after graft harvesting from the anterior iliac crest despite good surgical technique. This complication is well known and most of these fractures heal uneventfully if treated conservatively. However, if anatomical and technical considerations are respected, the patient could be spared this inconvenience. Based on a literature review, we discuss the procedure's potential complications and how to avoid them in an update.

Posterior iliac crest pain after posterolateral fusion with or without iliac crest graft harvest

BACKGROUND CONTEXT

Considerable debate exists regarding the incidence of persistent pain from the iliac crest bone graft (ICBG) harvest site. Different study designs have led to a variety of reported rates.

PURPOSE

The purpose of this study was to determine the incidence and severity of bone graft site pain after iliac crest harvest.

STUDY DESIGN

Cross-sectional.

PATIENT SAMPLE

One hundred and twelve patients, who had a posterior lumbar fusion, seen at a tertiary spine center for a routine postoperative visit.

OUTCOME MEASURES

Numeric rating scales (0-10) for pain over lower back, right, and left posterior iliac crests.

METHODS

An independent investigator, not directly involved in the care of the patient and unaware of the type of bone graft used in the fusion, examined the patient for tenderness over the surgical site as well as the left and right posterior iliac crest. After the examination, data on the source of grafting material, complications during harvest, and backfilling of the graft site defect were collected from the medical records. The patients were then classified as to whether ICBG was harvested or not. Chi-square test was used to determine any difference in the proportion of iliac crest pain between the bone graft group and no bone graft group. Correlations between body mass index (BMI), time since surgery, and the incidence and severity of bone graft site pain were also determined.

RESULTS

There were 72 women and 40 men with a mean age of 56.6 years (range, 16-84). Mean follow-up was 41 months (range, 6-211 months) with a median of 25 months. Iliac crest bone graft was harvested in 53 (47.3%) patients through the midline incision used for lumbar fusion. In 59 patients (52.7%), recombinant human bone morphogenetic protein-2 was used with no graft harvest. There was no statistically significant difference in the proportion of patients complaining of tenderness over both or either iliac crest between the two groups. Only 10 patients had pain over the same crest from which the graft was harvested. No correlations between number of levels fused, levels fused, BMI, length of follow-up, and the incidence and severity of bone graft site pain were seen.

CONCLUSIONS

The results of this study highlight the difficulty in differentiating pain originating from the graft site versus residual low back pain. The incidence of pain over the iliac crest was similar in patients in which iliac crest was harvested and those in which no graft was harvested.

Accelerating autograft maturation in instrumented posterolateral lumbar spinal fusions without donor site morbidity

Properly harvested iliac crest bone autograft applied to a meticulously prepared fusion bed produces a consistently high rate of fusion with a low incidence of donor site morbidity. Some reports advocate substituting bone morphogenic protein (BMP) for iliac crest bone autograft, but in posterolateral lumbar spinal fusion, BMP appears better suited to facilitate iliac crest bone autograft maturation than to substitute for it. In this single-center, nonrandomized, prospective study (minimum 2-year follow-up), cancellous-only iliac crest bone autograft was harvested for use in posterolateral lumbar spinal fusion. Reviewers blinded to graft condition and age assigned fusion scores to the random radiographs of 31 consecutive patients who underwent 1- to 3-level posterolateral lumbar spinal fusion using iliac crest bone autograft supplemented with either an implanted spinal fusion stimulator or BMP. There was no significant immediate or remote iliac crest bone autograft harvest morbidity, and there was a significant reduction in pain scores postoperatively (P<.001). At 12 months, BMP radiographs were more likely than spinal fusion stimulator radiographs to be rated as fused (P<.019). All BMP patients were deemed fused at 12 months and all spinal fusion stimulator patients at 24 months. In this study, iliac crest bone autograft supplemented with either BMP or spinal fusion stimulator resulted in a solid contiguous fusion without significant iliac crest bone autograft harvest-related morbidity. Bone morphogenic protein-supplemented iliac crest bone autograft fused at a faster rate, producing the more mature-appearing, trabeculated, robust fusion.

Iliac crest reconstruction to reduce donor-site morbidity: technical note

The design of the study includes case series, technical note and review of the literature. Autogenous bone graft (autograft) harvest from the iliac crest remains the gold standard substrate for spinal fusion. Persistent donor-site pain is the most common cause of morbidity after autograft harvest, occurring in one-third of patients. Numerous techniques for reducing donor-site morbidity have been reported in the literature, including infusion of analgesics and post-harvest reconstruction of the iliac crest with ceramics, allograft or bone morphogenic protein. A case series of patients undergoing spinal fusion surgery is reported. All patients were treated with iliac crest reconstruction using Calcium Phosphate Cement and follow-up data of persistent donor-site pain was collected. Twelve patients underwent autograft harvest with iliac spine reconstruction using Calcium Phosphate Cement. 42% (5) had persistent donor-site pain (after 3 months). All pain scores were less than or equal to 2 out of 10 (mean 1.25). In conclusion, iliac spine reconstruction using Calcium Phosphate Cement following autogenous bone graft harvest is a relatively simple procedure which failed to decrease the incidence of donor-site morbidity in our patient population.

The incidence of donor site pain after bone graft harvesting from the posterior iliac crest may be overestimated: a study on spine fracture patients

STUDY DESIGN

A retrospective cohort study on patients with traumatic vertebral fractures who underwent fusion with iliac crest bone.

OBJECTIVE

To evaluate the influence of low back surgery on donor site attributed pain, we compared donor site pain between patients who underwent high and low level fusions.

SUMMARY OF BACKGROUND DATA

The most common complication of posterior iliac crest bone graft harvesting is postoperative pain at the donor site. The incidence of donor site pain after bone graft harvesting from the posterior iliac crest is mainly reported from studies in patients who underwent low lumbar or lumbosacral surgery. The close proximity of the primary surgery to the iliac crest could interfere with the reported incidence of donor site pain.

METHODS

Questionnaires regarding the iliac crest morbidity were sent to patients who underwent instrumented posterolateral fusion after traumatic spinal fractures. The incidence of donor site attributed pain was compared between patients whose fusion was between T2 and L2, with patients whose fusion extended to L3 or more caudally.

RESULTS

In patients with a fusion of high levels, the donor site pain was significantly lower compared with patients with fusion of low levels (14.3% vs. 40.9%).

CONCLUSION

Patients probably cannot differentiate between donor site pain and residual low back pain. The reported incidence of pain related to posterior iliac crest bone graft harvesting may therefore be overestimated.

Biomechanical evaluation of conventional internal contemporary spinal fixation techniques used for stabilization of complete sacroiliac joint separation: a 3-dimensional unilaterally isolated experimental stiffness study

STUDY DESIGN

Comparative 3-dimensional biomechanical testing.

OBJECTIVE

To compare 5 fixation techniques, 3 using screws or screw and plates and 2 spinal, used for stabilization of complete unilateral sacroiliac dislocation in composite models.

SUMMARY OF BACKGROUND DATA

Harrington compression rods have been used for posterior iliosacral stabilization. Recently, the use of compact spinal instrumentation has been introduced for stabilization of iliosacral joint separation to achieve immediate and permanent stability, allowing early mobilization. To the authors' knowledge, no comparative mechanical studies between commonly used internal fixation techniques and contemporary spinal instrumentation have been performed.

METHODS

Fifteen identical composite models of the left hemipelvis and sacrum were used to simulate consistently the "worst-case scenario" of complete unilateral sacroiliac dislocation. Subgroups of 3 models each were used to apply 5 (A-E) alternative fixation iliosacral joint fixation techniques: 1 multiaxial 7.5 mm Cotrel-Dubousset screw inserted in the posterior superior iliac spine and connected with a long Cotrel-Dubousset horizontal rod with 6.5 mm multiaxial Cotrel-Dubousset screws inserted bilaterally in the S1 pedicles (technique A); 1 multiaxial 7.5 mm Cotrel-Dubousset titanium pedicle screw inserted in the posterior superior iliac spine and connected with a short horizontal Cotrel-Dubousset-rod to a 6.5 mm multiaxial Cotrel-Dubousset-screw inserted to the ipsilateral S1 pedicle (technique B); 1, 6.5 mm cancellous AO-screw (technique C); 2, 6.5 mm cancellous AO screws (technique D); and 2 dynamic stainless steel compression plates (technique E) placed anteriorly. Constructs were biomechanically tested. The ilium was unilaterally rigidly fixed, the sacrum was put horizontal in the mediolateral direction with a forward tilt of 30 degrees (close to physiologic conditions) in the sagittal plane, and a vertical quasi-static compressive load ranging from 0 to 500 N was applied on the endplate of S1, reproducing a "worst case" loading scenario. Construct stiffness, frontal plus sagittal kinematics, and iliosacral joint gap size for all 5 techniques were measured.

RESULTS

The construct stiffness (N/mm +/- standard deviation) ranged for model: A, 121 +/- 18; B, 78 +/- 10; C, 168 +/- 13; D, 193 +/- 42; and E, 145 +/- 4. All other parameters exhibited minor variations between the different techniques of fixation: at the 400 N load level, the maximum iliosacral gap globally ranged 0.9-2.8 mm, the maximum mediolateral sacral tilt ranged 1.3-2.4 degrees, and the maximum anteroposterior sacral tilt ranged 0.6-3.0 degrees.

CONCLUSIONS

The iliosacral fixation with 2 6.5 mm AO-cancellous screws for complete sacroiliac dislocation demonstrated the highest stiffness and the short spinal instrumentation the poorest stiffness. All other fixation techniques could be generally considered of equivalent stability value.

Failure of reconstitution of open-section, posterior iliac-wing bone graft donor sites after lumbar spinal fusion. Observations with implications for the etiology of donor site pain

The objective of this cohort study--conducted at a regional trauma unit in southern Ontario, Canada--was to review the imaging history of open-section, iliac-wing bone graft donor sites in lumbar fusion patients. Intervention entailed review of available X-ray and CT scan images for all patients undergoing lumbar fusion with iliac autograft in the senior author's practice over a 4-year period. Outcome was radiographic confirmation of the absence of bony reconstitution at the iliac harvest site. Of 239 primary fusions performed, 209 complete imaging records were available for review. The images of a further 20 patients who had surgery with the senior author prior to the study period and who presented at the office in the first half of 2000 were also assessed. All cases showed persistence of the iliac donor harvest site defect. Only minimal marginal sclerosis to suggest attempted remodeling was observed. We conclude that iliac-wing bone graft donor sites do not remodel. Given that iliac harvesting is known to increase strain in the pelvis, and that lumbosacral stabilization increases stress in the pelvis, permanent deficiency of iliac bone stock at donor harvest site may be a factor in both primary donor site pain and the observed high frequency of this problem in lumbosacral fusion patients.

A cost analysis of bone morphogenetic protein versus autogenous iliac crest bone graft in single-level anterior lumbar fusion

An economic model was developed to compare costs of stand-alone anterior lumbar interbody fusion with recombinant human bone morphogenetic protein 2 on an absorbable collagen sponge versus autogenous iliac crest bone graft in a tapered cylindrical cage or a threaded cortical bone dowel. The economic model was developed from clinical trial data, peer-reviewed literature, and clinical expert opinion. The upfront price of bone morphogenetic protein (3380 dollars) is likely to be offset to a significant extent by reductions in the use of other medical resources, particularly if costs incurred during the 2 year period following the index hospitalization are taken into account.

The use of bioabsorbable implants in the spine

BACKGROUND CONTEXT

Bioabsorbable implants are commonplace in sports medicine surgeries, especially in shoulder and knee ligamentous reconstruction. Their use is now expanding to the realm of spinal reconstructive surgery. Newer polymers offer reduced incidence of the side effects of aseptic sterile sinus formation and have appropriate resorption time parameters for spine use. These new bioabsorbable materials confer initial and intermediate-term stability that is adequate for stable bony healing in various applications. The majority of human clinical applications in the spine that have been documented involve bone graft harvest site reconstruction, posterior spinal graft containment, anterior interbody reconstruction and anterior cervical and lumbar spine tension band plating.

PURPOSE

The purpose of this review article is to highlight the indications and outcomes of the use of bioabsorbable implants in specific spinal applications.

STUDY DESIGN

A comprehensive literature review of the English and non-English literature on bioabsorbable implant technology.

METHODS

A comprehensive literature review was performed to gather basic science, animal and human data on the use of bioabsorbable implants in spinal surgery.

RESULTS

Bioabsorbable implants have demonstrated strength and resorption characteristics commensurate with the physiologic and biomechanical requirements of the human spinal axis. Histologic sampling has demonstrated successful time-patterned resorption accompanied by bony replacement and remodeling of intervertebral cage devices in the animal model.

CONCLUSION

Bioresorbable compounds appear to have a role in specific spinal reconstructive procedures. Their radiolucent nature improves image assessment of fusion healing, and their time-engineered resorption characteristics allow controlled dynamization in interbody and plate applications. Their widespread use and acceptance may increase dramatically as further research and clinical studies report on their safety and efficacy.

Spinal applications of bioabsorbable implants

With the increasing use of bioabsorbable implants in a variety of clinical conditions, potential advantages in selected spinal applications are now being realized. Newer polymers with biomechanical properties relevant to the requirements of specific spinal implants and resorption rates appropriate for specific spinal applications are being developed. These new materials offer the necessary biomechanical stability of conventional spinal implants without the sequelae associated with metallic implants such as long-term loosening, implant migration, and imaging interference. At this time, the majority of clinical applications for these new polymers have involved tension band plating in the lumbar and anterior cervical spine, anterior spinal interbody reconstruction, posterior bone graft containment, and bone graft harvest site reconstruction.

Spinal applications of bioabsorbable implants

With the increasing use of bioabsorbable implants in a variety of clinical conditions, potential advantages in select spinal applications are now being realized. Newer polymers with biomechanical properties relevant to the requirements of specific spinal implants and resorption rates appropriate for specific spinal applications are being developed. These new materials offer the necessary biomechanical stability of conventional spinal implants without the sequelae associated with metallic implants such as long-term loosening, implant migration, and imaging interference. At this time, the majority of clinical applications for these new polymers have involved tension band plating in the lumbar and anterior cervical spine, anterior spinal interbody reconstruction, posterior bone graft containment, and bone graft harvest site reconstruction.

Natural history of posterior iliac crest bone graft donation for spinal surgery: a prospective analysis of morbidity

STUDY DESIGN

A prospective study was conducted to examine bone graft donor site morbidity in 106 consecutive patients undergoing posterior spinal fusion.

OBJECTIVES

To perform a prospective analysis of donor site morbidity, to document the incidence of major complications, and to collect information on the impact of autologous bone graft harvesting from the posterior iliac crest on the overall outcome of spinal surgery.

SUMMARY OF BACKGROUND

Bone graft harvesting from the posterior iliac crest for spinal fusion is a source of significant morbidity. Previous retrospective case studies indicate that minor complications are common, but they do not define the natural history and complications of posterior iliac crest bone graft harvesting.

METHODS

A standardized harvesting technique was used. At 3, 6, and 12 months after surgery, the patients completed a proforma questionnaire rating symptoms on a visual analog scale and underwent a postoperative examination by the surgeon. Finally, overall surgical outcome was assessed at 12 months.

RESULTS

The major component of morbidity is donor site pain. Mean pain scores were 1.640 at 3 months, 1.812 at 6 months, and 1.207 at 12 months. The pain at 12 months was significantly less than at 3 and 6 months (P = 0.005), with a trend toward the highest scores at 6 months. A pain score of 0 was reported by 55% of the patients. Local sensory loss was found in 10% of the patients. Outcome assessment showed significant differences in morbidity for surgery performed at different spinal levels (P = 0.001), with lumbosacral surgery resulting in worse outcomes than either cervical (P < 0.05) or thoracolumbar (P < 0.05) surgery. Significantly higher visual analog scores were observed at 6 months in patients with poorer overall outcomes.

CONCLUSIONS

According to this study, it is reasonable to reassure patients that a good result from spinal surgery will not be compromised by severe symptoms or major morbidity secondary to posterior iliac crest bone graft donation. Before surgery, patients may be advised concerning the risks of donor site pain, which improves significantly by 12 months, local tenderness, and uncommonly localized sensory loss.

A modified technique for harvesting full-thickness iliac crest bone graft

STUDY DESIGN

A prospective follow-up study of patients undergoing anterior spinal decompression and bone graft with cortical iliac crest bone.

OBJECTIVE

To describe a modified technique for harvesting cortical bone graft from the anterior iliac crest.

SUMMARY OF BACKGROUND DATA

Cortical bone graft from the iliac crest frequently is used in various orthopedic and spinal procedures. The resulting defect in the iliac crest has been associated with many complications.

METHODS

Twenty patients were included in this study. All had burst vertebral fracture requiring anterior spinal decompression and cortical bone grafting. The modified technique was used for harvesting the iliac crest bone graft in all patients.

RESULTS

All patients were satisfied with the appearance of the iliac crest. None reported chronic pain at the graft site. None had fracture of the iliac wing, and none had symptoms related to the lateral femoral cutaneous nerve or herniation of pelvic contents through the bony defect in the iliac wing.

CONCLUSION

This modified technique is technically straightforward and cost-effective. It preserves the contour and shape of the iliac crest and avoids cosmetic deformities and chronic pain at the graft site. It creates a window in the iliac wing rather than disrupting the continuity of the iliac crest, which leaves the iliac wing structurally stronger than with currently used techniques.

Complete pelvic ring failure after posterior iliac bone graft harvesting

STUDY DESIGN

Case report.

OBJECTIVE

To present a rare complication of posterior iliac bone graft harvesting.

SUMMARY OF BACKGROUND DATA

Although iliac bone graft harvesting is a common procedure in spinal surgery, it is not without complications. One such complication is fracture of the ilium that is seen most often in older women with osteopenia.

METHOD

In this case a severe complication of posterior iliac bone graft harvesting was identified in a patient with steroid-induced osteoporosis that led to multiple pelvic fracture, nonunions, and eventual failure of the entire pelvic ring. Imaging studies showed osteoporotic bone and multiple nonunions of the pelvis with structural collapse.

RESULTS

Staged sequential platings of the iliac wings were performed to stabilize the pelvis. The initial fixation of the left iliac wing apparently united after hardware failure. The right iliac wing was successfully fixed with plates supplemented with bone cement and allograft. Anterior fixation was planned.

CONCLUSIONS

Care should be taken when considering autograft harvesting in patients with risk factors for osteoporosis. The outcome could be debilitating.

Proper design of clinical trials for the assessment of bone graft substitutes

To assess the effectiveness and safety of engineered bone graft substitutes proper, clinical trials will need to be performed. Although the randomized placebo controlled prospective clinical trial is the gold standard, clinical trials of this design are difficult to perform in the surgical setting. At this writing, several clinical trials evaluating bone graft materials have been performed, and much was learned toward improving the design of future studies. This article reviews alternatives to the placebo controlled randomized clinical trials in the surgical setting. The importance of long term surveillance is emphasized.