Iain W. McCall

Autologous chondrocyte implantation for cartilage repair: monitoring its success by magnetic resonance imaging and histology

Autologous chondrocyte implantation is being used increasingly for the treatment of cartilage defects. In spite of this, there has been a paucity of objective, standardised assessment of the outcome and quality of repair tissue formed. We have investigated patients treated with autologous chondrocyte implantation (ACI), some in conjunction with mosaicplasty, and developed objective, semiquantitative scoring schemes to monitor the repair tissue using MRI and histology. Results indicate repair tissue to be on average 2.5 mm thick. It was of varying morphology ranging from predominantly hyaline in 22% of biopsy specimens, mixed in 48%, through to predominantly fibrocartilage, in 30%, apparently improving with increasing time postgraft. Repair tissue was well integrated with the host tissue in all aspects viewed. MRI scans provide a useful assessment of properties of the whole graft area and adjacent tissue and is a noninvasive technique for long-term follow-up. It correlated with histology (P = 0.02) in patients treated with ACI alone.

Induced pain referral from posterior lumbar elements in normal subjects.

Patterns of pain referral, induced from the posterior elements, have been studied in normal volunteer subjects. A series of intracapsular and pericapsular injections were performed at the L1 - 2 and L4-5 levels. The areas of pain referral indicate overlap between the upper and lower lumbar spine. It is also shown that the pericapsular and intrafacetal pain referral areas are similar and that the upper lumbar spine is more sensitive than the lower.

Longitudinal study of vertebral type-1 end-plate changes on MR of the lumbar spine

The purpose of this study was to investigate the temporal evolution of type-1 end-plate changes on MRI in patients with degenerative disease of the lumbar spine and to evaluate whether any correlation exists between such evolution and the change in patients’ symptoms. Forty-four patients with 48 Modic type-1 end-plate changes (low TI signal and high T2 signal) were studied. All patients had an initial and a follow-up non-contrast lumbar MRI with variable intervals between the studies (12–72 months). Severity of the end-plate changes was assessed by eyeball estimation. Correlation with patients’ symptoms was studied with the help of the Visual Analogue Score (VAS), Oswestry Questionnaire Score (OQS) and patients’ subjective assessment. Of the 48 disc levels with type-1 changes, 18 (37.5%) converted fully to type 2 (high T1 signal and intermediate to high T2 signal), 7 (14.6%) partially converted to type 2, 19 (39.6%) became worse (i.e. type 1 changes became more extensive) and 4 (8.3%) showed no change. Higher average VAS (5.7) and OQS (42.3) scores were noted in patients where there was worsening type-1 change and lower scores (3.8 and 27, respectively) were seen in those where there was conversion to type-2 change. These trends, however, did not reach statistical significance (P values 0.16 and 0.09 for VAS and OQS, respectively). The statistical relationship was stronger after exclusion of patients with confounding factors (i.e. changes in lumbar MRI other than end-plate changes that could independently explain the evolution of patients’ symptoms) with P-values of 0.08 and 0.07 for VAS and OQS, respectively. Type-1 end-plate change represents a dynamic process and in a large majority of cases either converts to type-2 change or becomes more extensive. The evolution of type-1 change relates to change in patient’s symptoms, but not to a statistically significant level.

Apophyseal injection of local anesthetic as a diagnostic aid in primary low-back pain syndromes.

Twenty-five out of 41 adult patients suffering from their first attack of acute low-back pain were subjected to local anesthetic injection into the maximally tender lumbar apophyseal joints under controlled conditions. Two clinical syndromes can be identified according to whether the patients responded to the facet injection or not. Various clinical differences were statistically significant and included a wider than normal spinal canal in the responding group. The clinical significance of these two distinct groups is discussed in detail.

The diagnostic accuracy of MR imaging in osteoid osteoma

Abstract Objective. To analyse the MR imaging appearances of a large series of osteoid osteomas, to assess the ability of MR imaging to detect the tumour, and to identify potential reasons for misdiagnosis. Design and patients. The MR imaging findings of 43 patients with osteoid osteoma were reviewed retrospectively and then compared with other imaging modalities to assess the accuracy of MR localisation and interpretation. Results. The potential for a missed diagnosis was 35% based solely on the MR investigations. This included six tumours which were not seen and nine which were poorly visualised. The major determinants of the diagnostic accuracy of MR imaging were the MR technique, skeletal location, and preliminary radiographic appearances. There was a wide spectrum of MR signal appearances of the lesion. The tumour was identified in 65% of sequences performed in the axial plane. The nidus was present in only one slice of the optimal sequence in 27 patients. Reactive bone changes were present in 33 and soft tissue changes in 37 patients. Conclusion. Reliance on MR imaging alone may lead to misdiagnosis. As the osteoid osteoma may be difficult to identify and the MR features easily misinterpreted, optimisation of MR technique is crucial in reducing the risk of missing the diagnosis. Unexplained areas of bone marrow oedema in particular require further imaging (scintigraphy and CT) to exclude an osteoid osteoma.

Does the thickness of the vertebral subchondral bone reflect the composition of the intervertebral disc

Degeneration of the intervertebral disc, seen radiologically as loss of disc height, is often associated with apparent remodelling in the adjacent vertebral body. In contrast, maintenance or apparent increase in disc height is a common finding in osteoporosis, suggesting the properties of the intervertebral disc may be dependent on those of the vertebral body or vice versa. We have investigated this relationship by measuring the radiological thickness of the subchondral bone and comparing it to the chemical composition of the adjacent disc. Sagittal slabs were sampled from lumbar spines obtained at autopsy and X-rayed microfocally. The thickness of the subchondral bone was measured and correlated with the composition of the adjacent intervertebral disc. Eighty-three cadaveric endplates were studied from individuals aged 17–85 years. There was regional variation in thickness of the subchondral bone, being greater adjacent to the annulus than the nucleus, and the endplates cranial to the disc were thicker than those caudal. There was a positive correlation between the thickness of the subchondral bone and the proteoglycan content of the adjacent disc, particularly in the region of the nucleus. A weaker correlation was seen here between water content and thickness, whilst there was no significant correlation at the annulus or between the bone thickness and collagen content. The positive relationship between the radiographic thickness of vertebral subchondral bone and the proteoglycan content of the adjacent disc seen in human cadaveric material could be due to the bone responding to a greater hydrostatic pressure being exerted by discs with higher proteoglycan content than by those with less proteoglycan present. It is suggested that while this is true in “normal” specimens, the relationship becomes altered in disease states, possibly because of changes to the nutritional pathway of the disc, with resultant endplate-bone remodelling affecting the flow of solutes to and from the intervertebral disc.

Marginal erosive discovertebral ”Romanus” lesions in ankylosing spondylitis demonstrated by contrast enhanced Gd-DTPA magnetic resonance imaging

Abstract  Objective. To assess the value of Gd-DTPA magnetic resonance (MR) imaging in the demonstration of marginal destructive discovertebral Romanus lesions in ankylosing spondylitis. Design and patients. A prospective study of Gd-DTPA MR imaging was performed in 39 patients with a clinical diagnosis of ankylosing spondylitis and typical Romanus lesions seen on radiographs of the thoracolumbar spine. MR morphological appearances and signal intensity changes at the discovertebral junctions were analysed and compared with the radiographic findings. Results. Ninety-nine discovertebral junctions with Romanus lesions showed low signal intensity on T1-weighted and high signal on T2-weighted and T1-weighted postcontrast images at the vertebral corners consistent with oedematous hyperaemic inflammatory tissue. There were nine discovertebral junctions with similar MR findings but normal radiographs. Fifty-three discovertebral junctions showed syndesmophyte formation with increased signal intensity on both T1- and T2-weighted images with no contrast enhancement. Sixty-five discovertebral junctions showed a mixture of radiographic features and varied high and low signal changes at the vertebral rim on MR imaging with rims of enhancement in the vertebral body following contrast administration. Conclusion. Gd-DTPA MR imaging demonstrates a variable signal pattern and degree of contrast enhancement which may reflect the evolutionary stages of discovertebral enthesitis in ankylosing spondylitis. MR imaging may identify early erosive changes in radiographically normal vertebra. The role of MR imaging needs further investigation.

Intra-articular osteoid osteoma

Osteoid osteomas located within the capsule of a joint are uncommon and present challenging diagnostic difficulties. Twelve patients with an intra-articular osteoid osteoma were studied retrospectively to determine the spectrum of clinical and radiological findings. The features differ significantly from the well known classical hallmarks of the extra-articular lesion. The symptoms are non-specific with pain similar to other common joint disorders and the response to salicylate less precise. On plain radiography intra-articular lesions are difficult to identify, lacking the florid periosteal new bone and intense perifocal sclerotic reaction. A detectable focal lesion is commonly absent with considerable delay between the onset of symptoms and radiological detection of the tumour nidus. Bone scintigraphy and computed tomography (CT) are essential for an accurate and early diagnosis. These imaging techniques reveal abnormalities in bone and cartilage growth, new bone formation and sclerosis distant from the tumour on either side of the joint, and disruption of the articular surface. Radiological follow up after surgery shows that these changes can be reversible, especially when the diagnosis is made early.

Autologous chondrocyte implantation with bone grafting for osteochondral defect due to posttraumatic osteonecrosis of the hip- : a case report

Copyright© Taylor & Francis 2006. ISSN 1745–3674. Printed in Sweden – all rights reserved. DOI 10.1080/17453670610046208 A 31-year-old man sustained a severe fracture dislocation of the left hip as a result of a road traffic accident in 2001. There was a subcapital fracture of the femoral head with complete separation of the head from the femoral neck, and posterior wall fracture of the acetabulum (Figure 1). The initial management was open reduction and internal fixation, and the immediate postoperative radiograph showed the screws to be in a satisfactory position within the femoral head. After 1 year, the patient was walking with one crutch and the range of movement of the left hip was restricted due to severe pain. At this time, his hip score (HS) was 52 of a possible 100 (Harris 1969). Radiography demonstrated a united femoral fracture, but the fixation screws had penetrated the hip joint due to collapse of the osteonecrotic femoral head, and there was narrowing of the joint space (Figure 2). Taking the young age of the patient into account, we decided to proceed with autologous chondrocyte implantation (ACI). The first stage was performed 21 months after the original injury. During an arthroscopy of the ipsilateral knee, 240 mg of macroscopically normal full depth cartilage was harvested from the low load area of the medial trochlea. The tissue was transported to a dedicated clinical cell culture laboratory for isolation and expansion of the chondrocytes as previously

Acute traumatic intraosseous disc herniation.

The clinical, radiologic, and discographic findings are reviewed in eight patients with acute traumatic intraosseous disc herniation. The syndrome should be considered in adolescent patients having severe back pain with limited radiation to the upper thigh, following significant compression/flexion stress to the spine. The intraosseous disc herniation can be confirmed by discography and reproduction of symptoms during the procedure is a helpful confirmatory feature. The radiologic natural history of the lesion is presented, and the role of bone scintigraphy is discussed. This type of injury may be responsible for considerable pain and disability in the adolescent age group and has proved extremely difficult to manage except by conservative treatment and analgesics.