W. Bartlett

Autologous chondrocyte implantation versus matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee: A PROSPECTIVE, RANDOMISED STUDY

Autologous chondrocyte implantation (ACI) is used widely as a treatment for symptomatic chondral and osteochondral defects of the knee. Variations of the original periosteum-cover technique include the use of porcine-derived type I/type III collagen as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) using a collagen bilayer seeded with chondrocytes. We have performed a prospective, randomised comparison of ACI-C and MACI for the treatment of symptomatic chondral defects of the knee in 91 patients, of whom 44 received ACI-C and 47 MACI grafts. Both treatments resulted in improvement of the clinical score after one year. The mean modified Cincinnati knee score increased by 17.6 in the ACI-C group and 19.6 in the MACI group (p = 0.32). Arthroscopic assessments performed after one year showed a good to excellent International Cartilage Repair Society score in 79.2% of ACI-C and 66.6% of MACI grafts. Hyaline-like cartilage or hyaline-like cartilage with fibrocartilage was found in the biopsies of 43.9% of the ACI-C and 36.4% of the MACI grafts after one year. The rate of hypertrophy of the graft was 9% (4 of 44) in the ACI-C group and 6% (3 of 47) in the MACI group. The frequency of re-operation was 9% in each group. We conclude that the clinical, arthroscopic and histological outcomes are comparable for both ACI-C and MACI. While MACI is technically attractive, further long-term studies are required before the technique is widely adopted.

Autologous chondrocyte implantation at the knee using a bilayer collagen membrane with bone graft: A PRELIMINARY REPORT

Autologous chondrocyte implantation (ACI) is a technique used for the treatment of symptomatic osteochondral defects of the knee. A variation of the original periosteum membrane technique is the matrix-induced autologous chondrocyte implantation (MACI) technique. The MACI membrane consists of a porcine type-I/III collagen bilayer seeded with chondrocytes. Osteochondral defects deeper than 8 to 10 mm usually require bone grafting either before or at the time of transplantation of cartilage. We have used a variation of Petersons ACI-periosteum sandwich technique using two MACI membranes with bone graft which avoids periosteal harvesting. The procedure is suture-free and requires less operating time and surgical exposure. We performed this MACI-sandwich technique on eight patients, five of whom were assessed at six months and one year post-operatively using the modified Cincinnati knee, the Stanmore functional rating and the visual analogue pain scores. All patients improved within six months with further improvement at one year. The clinical outcome was good or excellent in four after six months and one year. No significant graft-associated complications were observed. Our early results of the MACI-sandwich technique are encouraging although larger medium-term studies are required before there is widespread adoption of the technique.

WHO IS THE IDEAL CANDIDATE FOR AUTOLOGOUS CHONDROCYTE IMPLANTATION

We investigated the prognostic indicators for collagen-covered autologous chondrocyte implantation (ACI-C) performed for symptomatic osteochondral defects of the knee. We analysed prospectively 199 patients for up to four years after surgery using the modified Cincinnati score. Arthroscopic assessment and biopsy of the neocartilage was also performed whenever possible. The favourable factors for ACI-C include younger patients with higher pre-operative modified Cincinnati scores, a less than two-year history of symptoms, a single defect, a defect on the trochlea or lateral femoral condyle and patients with fewer than two previous procedures on the index knee. Revision ACI-C in patients with previous ACI and mosaicplasties which had failed produced significantly inferior clinical results. Gender (p = 0.20) and the size of the defect (p = 0.97) did not significantly influence the outcome.

Autologous chondrocyte implantation for osteochondral lesions in the knee using a bilayer collagen membrane and bone graft: a two- to eight-year follow-up study

Matrix-induced autologous chondrocyte implantation (MACI) is an established technique used to treat osteochondral lesions in the knee. For larger osteochondral lesions (> 5 cm(2)) deeper than approximately 8 mm we have combined the use of two MACI membranes with impaction grafting of the subchondral bone. We report our results of 14 patients who underwent the bilayer collagen membrane technique (BCMT) with a mean follow-up of 5.2xa0years (2 to 8). There were 12 men and two women with a mean age of 23.6 years (16 to 40). The mean size of the defect was 7.2 cm(2) (5.2 to 12xa0cm(2)) and were located on the medial (ten) or lateral (four) femoral condyles. The mean modified Cincinnati knee score improved from 45.1 (22 to 70) pre-operatively to 82.8 (34 to 98) at the most recent review (p < 0.05). The visual analogue pain score improved from 7.3 (4 to 10) to 1.7 (0 to 6) (p < 0.05). Twelve patients were considered to have a good or excellent clinical outcome. One graft failed at sixxa0years. The BCMT resulted in excellent functional results and durable repair of large and deep osteochondral lesions without a high incidence of graft-related complications.

The use of autologous chondrocyte implantation following and combined with anterior cruciate ligament reconstruction

We report our experience of using autologous chondrocyte implantation (ACI) to treat osteochondral defects of the knee in combination with anterior cruciate ligament (ACL) reconstruction. The outcome of symptomatic osteochondral lesions treated with ACI following previous successful ACL reconstruction is also reviewed. Patients were followed for a mean of 23 months. Nine patients underwent ACL reconstruction in combination with ACI. Mean modified Cincinnati knee scores improved from 42 to 69 following surgery. Seven patients described their knee as better and two as the same. A second group of nine patients underwent ACI for symptomatic articular cartilage defects following previous ACL reconstruction. In this group, the mean modified Cincinnati knee score improved from 53 to 62 after surgery. Six patients described their knee as better and three as worse. Combined treatment using ACI with ACL reconstruction is technically feasible and resulted in sustained improvement in pain and function. The results following previous ACL reconstruction also resulted in clinical improvement, although results were not as good as following the combined procedure.RésuméNous rapportons notre expérience de la greffe autologue de chondrocytes (ACI) pour traiter les lésions ostéochondrales du genou en combinaison avec la reconstruction du LCA. Le résultat du traitement par ACI des lésions ostéochondrales symptomatiques, après un bon résultat de la reconstruction précédente du LCA est aussi examiné. Les malades ont été suivis en moyenne 23 mois. Neuf malades ont eu une intervention combinée. La moyenne du score modifié de Cincinnati s’est améliorée de 42 à 69 après la chirurgie. Sept malades ont décrit leur genou comme meilleur et deux comme le même. Un deuxième groupe de neuf malades a subi une greffe de chondrocytes pour lésion symptomatique du cartilage articulaire après une reconstruction du LCA. Dans ce groupe, la moyenne du score modifié de Cincinnati s’est améliorée de 53 à 62 après l’intervention. Six malades ont décrit leur genou comme meilleur et trois comme pire. Le traitement combiné qui utilise la greffe de chondrocyte avec la reconstruction du LCA est techniquement faisable et a apporté une amélioration notable de la douleur et de la fonction. L’intervention effectuée après la reconstruction antérieure du LCA apporte une amélioration clinique, bien que les résultats ne soient pas aussi bons qu’après la procédure combinée.

Diagnosing an extra-axial chordoma of the proximal tibia with the help of brachyury, a molecule required for notochordal differentiation

Chordomas are rare malignant bone tumours considered to arise from notochordal remnants that persist in the axial skeleton. Although their morphology can resemble that of a carcinoma, chondrosarcoma or malignant melanoma, the axial location and their well-defined immunophenotype, including expression of cytokeratins (CK7/20/8/18/19) and S100, generally allow the diagnosis to be made with confidence once the possibility is considered. In contrast, making a robust diagnosis of an extra-axial chordoma has been difficult in the absence of specific markers for chordomas. We have recently shown in gene expression microarray and immunohistochemistry studies that brachyury, a transcription factor crucial for notochordal development, is a specific and sensitive maker for chordomas. We now present a case of an intracortical tibial tumour, with detailed report of the imaging, and morphological features consistent with a chordoma, where notochordal differentiation was demonstrated with an antibody to brachyury. The tumour cells were also positive for cytokeratins, including CK19, and S100, CEA, EMA and HMBE1, findings which support the diagnosis of chordoma. Brachyury can be employed as a marker of notochordal differentiation and help identify confidently, for the first time, extra-axial bone and soft tissue chordomas, and tumours which may show focal notochordal differentiation.

Cost and health status analysis after autologous chondrocyte implantation and mosaicplasty: a retrospective comparison.

OBJECTIVESnChondral defects of the knee cartilage are prevalent. Autologous chondrocyte implantation (ACI) and mosaicplasty are increasingly used to treat symptomatic knee defects. This study assessed the costs and health status outcomes after ACI and mosaicplasty.nnnMETHODSnPatients were eligible to participate in this cross-sectional study if they received ACI or mosaicplasty at the Royal National Orthopaedic Hospital between 1997 and 2001 or were on a waiting list for ACI. Secondary-care resource use was collected to 2 years postoperatively using a resource collection proforma. Participants responded to postal questions about sociodemographic characteristics and knee-related (Modified Cincinnati Knee Rating System) and general health status (EQ-5D).nnnRESULTSnFifty-three ACI, twenty mosaicplasty, and twenty-two patients waiting for ACI participated. The average cost per patient was higher for ACI (10,600 pounds sterling: 95 percent confidence interval [CI], 10,036 pounds sterling-11,214 pounds sterling) than mosaicplasty (7,948 pounds sterling: 95 percent CI, 6,957 pounds sterling-9,243 pounds sterling). Postoperatively, ACI and mosaicplasty patients (combined) experienced better health status than those waiting for ACI. ACI patients tended to have better health status outcomes than mosaicplasty patients (not statistically significant). Estimated average EQ-5D social tariff improvements for quality-adjusted life year (QALY) calculations were 0.23 (ACI) and 0.06 (mosaicplasty). Average costs per QALY were 23,043 pounds sterling (ACI) and 66,233 pounds sterling (mosaicplasty). The incremental cost effectiveness ratio (ICER) for providing ACI over mosaicplasty was 16,349 pounds sterling.nnnCONCLUSIONSnAverage costs were higher for ACI than mosaicplasty. However, both the estimated cost per QALY and ICER for providing ACI over mosaicplasty fell beneath an implicit English funding threshold of 30,000 pounds sterling per QALY. Prospective studies should include measures of utility to confirm the estimated cost utility ratios of ACI and mosaicplasty.

Custom-made hinged spacers in revision knee surgery for patients with infection, bone loss and instability

Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion. We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The SMILES spacer was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24-70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients. In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation.

Collagen-covered versus matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee: a comparison of tourniquet times

We have compared tourniquet times of two techniques of autologous chondrocyte implantation (ACI). Seventy-three patients underwent the collagen covered ACI technique (ACI-C) and 63 patients underwent the matrix-induced autologous chondrocyte implantation technique (MACI) for symptomatic osteochondral defects of the knee, at our centre, as part of a prospective trial. The mean tourniquet time in the ACI-C group was 80.7xa0min (range 47–126), and 61.5xa0min (range 27–100) in the MACI group, P=0.003. Tourniquet times greater than 90xa0min were required in 22 (31%) ACI procedures and 1 (2%) MACI procedure. The reduced implantation time for the MACI procedure is a clinically significant advantage, and allows cartilage resurfacing to be performed in combination with other techniques within safe tourniquet times.RésuméLes auteurs ont comparé les durées de garrot de deux techniques d’implantation de chondrocytes. 73 patients ont bénéficié d’une technique utilisant une membrane collagénique porcine suturée (ACI) et 63 d’une matrice collagénique collée (MACI) pour le traitement de perte de substance ostéochondrale dans le cadre d’un travail prospectif. La durée de garrot a été en moyenne de 80,7xa0min (47–126) pour le groupe ACI contre 61,5 (27–100) pour le groupe MACI (P=0.003). Une durée de garrot supérieure à 90xa0min a été nécessaire à 22 reprises (31%) pour la technique ACI et 1 (2%) pour le groupe MACI. La réduction du temps d’implantation pour la technique MACI est un avantage substantiel et permet de réaliser ce resurfaçage cartilagineux en combinaison avec d’autres techniques en toute sécurité quant à la durée de garrot.

Custom-made lateral femoral condyle replacement for traumatic bone loss: A case report

We report the case of a 24 year-old patient who underwent a novel treatment for a lateral femoral condyle fracture. The fracture was associated with extensive joint line depression and not considered suitable for conventional fixation techniques. Existing reconstructive options for such situations include unicondylar osteoarticular allograft, arthrodesis and arthroplasty. However, these techniques all present significant disadvantages, particularly in the management of active patients. We report our medium-term results following reconstruction using a custom-made lateral femoral condyle hemiarthroplasty replacement. Follow-up at 48 months revealed an excellent, pain-free level of function, with an Oxford Knee Score of 46/48, a Knee Society knee score of 87/100 and a functional score of 100/100. Radiographs demonstrated no evidence of prosthesis loosening or migration and no erosion of the lateral tibial plateau. The technique allows preservation of the remaining normal joint surface of the femur that may promote earlier and better restoration of function. Furthermore, the isolated condyle hemi-replacement maximises bone preservation, facilitating future anticipated revisions. The procedure presents an attractive alternative to other surgical options and their attendant problems. Further investigation into this technique is required before widespread adoption, though such studies will be compromised by the relative rarity of patients in whom the technique is indicated.