A Computed Tomography Scan Assessment of Synthetic Multiphase Polymer Scaffolds Used for Osteochondral Defect Repair

doi:10.1016/j.arthro.2010.06.023

Arthroscopy: The Journal of Arthroscopic & Related Surgery

Volume 27, Issue 1, January 2011, Pages 60-64

https://doi.org/10.1016/j.arthro.2010.06.023 Get rights and content

Purpose

To evaluate the radiographic response of a synthetic multiphase implant at various intervals after implantation and assess the nature of bone ingrowth into the implant location.

Methods

Patients undergoing autologous osteochondral transplantation for full-thickness condylar defects with the donor sites filled by use of a synthetic implant were evaluated by computed tomography (CT) scan for the density at both donor and recipient sites. Hounsfield unit (HU) readings were obtained at the synthetic implant, transplanted autograft plug, soft-tissue, cancellous bone, and cortical bone sites. The implant site material was graded by an established ossification quality score (range, 1 to 4).

Results

Nine patients underwent CT scans at intervals ranging from 2 to 63 months after surgery. This sequence of images tracked the potential development of bone ingrowth activity. Postoperative imaging confirmed complete autograft bone plug healing. The synthetic implant site CT scans showed a drop in density from 84 HU at 4 months to 19 HU by 13 months (fibrous scar density). The ossification quality score for all synthetic implants was 1 (tract filled with soft-tissue density) instead of 4 (cancellous bone). The transplanted autograft plug densities were consistent with and completely incorporated into the adjacent cancellous bone.

Conclusions

The synthetic multiphase implant showed no evidence of bone ingrowth, osteoconductivity, or ossification. The implant density declined over time to that of fibrous scar. This synthetic plug does not provide subchondral structural support for any tissue that grows over it. This study does not support the use of this implant for the primary repair of articular cartilage lesions.

Level of Evidence

Level IV, therapeutic case series.

Section snippets

Methods

A consecutive series of 20 patients who had undergone autologous osteochondral transplantation for isolated full-thickness defects on either the medial or lateral femoral condyle since 2004 were identified. Those in whom a synthetic multiphase implant (TruFit) was used to backfill the donor sites were contacted and invited to be part of this institutional review board–approved study.

Inclusion criteria were patients aged 18 to 60 years (mean, 40 years; range, 26 to 58 years) who had a prior

Results

In this study 9 patients (8 men and 1 woman) who had undergone osteochondral autograft transplantation with the donor sites filled by use of the TruFit device agreed to return for physical, radiographic, and CT scan evaluation at intervals ranging from 2 to 63 months after surgery. This sequence of studies documented the synthetic implant degradation over time (first endpoint) (Figs 1 and 2) and the potential development of bone ingrowth activity (second endpoint). The HU density scores for the

Discussion

The purpose of this study was to evaluate the radiographic and CT scan responses of the TruFit synthetic implant over time and to look for the presence of bone ingrowth. No bone ingrowth was found. This sequential CT scan evaluation showed a significant change in the multiphase synthetic implant site density from 79 to 84 HU at 2 to 4 months, dropping to 19 HU by 13 months. This density (19 HU) is consistent with fibrous scar (Table 1). The synthetic implant site density remained at the fibrous

Conclusions

The synthetic multiphase implant showed no evidence of bone ingrowth, osteoconductivity, or ossification. The synthetic implant density declined over time to that of fibrous scar. This synthetic plug does not provide subchondral structural support for any tissue that grows over it. This study does not support the use of this synthetic implant for the primary repair of articular cartilage lesions.

Acknowledgment

The authors thank Jennifer Heldreth for her assistance with this project.

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: Supported by the F. Alan Barber, MD, FACS Research Fund. The authors report no conflict of interest.

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Original ArticleA Computed Tomography Scan Assessment of Synthetic Multiphase Polymer Scaffolds Used for Osteochondral Defect Repair

Purpose

Methods

Results

Conclusions

Level of Evidence

Section snippets

Methods

Results

Discussion

Conclusions

Acknowledgment

Arthroscopy

Arthroscopy

Orthop Clin North Am

Arthroscopy

Arthroscopy

Arthroscopy

Arthroscopy

Original Article
A Computed Tomography Scan Assessment of Synthetic Multiphase Polymer Scaffolds Used for Osteochondral Defect Repair