Upper limb Osteochondral autologous transplantation for the
Transcription
Upper limb Osteochondral autologous transplantation for the
Upper limb Osteochondral autologous transplantation for the treatment of full-thickness articular cartilage defects of the shoulder M. Scheibel, C. Bartl, P. Magosch, S. Lichtenberg, P. Habermeyer From ATOS-Clinic Heidelberg, Heidelberg, Germany M. Scheibel, MD, Resident C. Bartl, MD, Resident P. Magosch, MD, Resident S. Lichtenberg, MD, Chief of the Department P. Habermeyer, MD, Chief of the Department Department of Shoulder and Elbow Surgery, ATOS-Clinic Heidelberg, Bismarckplatz 915, 69115 Heidelberg, Germany. Correspondence should be sent to Dr M. Scheibel. ©2004 British Editorial Society of Bone and Joint Surgery doi:10.1302/0301-620X.86B7. 14941 $2.00 J Bone Joint Surg [Br] 2004;86-B:991-7. Received 9 October 2003; Accepted after revision 9 December 2003 We performed eight osteochondral autologous transplantations from the knee joint to the shoulder. All patients (six men, two women; mean age 43.1 years) were documented prospectively. In each patient the stage of the osteochondral lesion was Outerbridge grade IV with a mean size of the affected area of 150 mm2. All patients were assessed by using the Constant score for the shoulder and the Lysholm score for the knee. Standard radiographs, magnetic resonance imaging and second-look arthroscopy were used to assess the presence of glenohumeral osteoarthritis and the integrity of the grafts. After a mean of 32.6 months (8 to 47), the mean Constant score increased significantly. Magnetic resonance imaging revealed good osseointegration of the osteochondral plugs and congruent articular cartilage at the transplantation site in all but one patient. Second-look arthroscopy performed in two cases revealed a macroscopically good integration of the autograft with an intact articular surface. Osteochondral autologous transplantation in the shoulder appears to offer good clinical results for treating full-thickness osteochondral lesions of the glenohumeral joint. However, our study suggests that the development of osteoarthritis and the progression of preexisting osteoarthritic changes cannot be altered by this technique. The spontaneous capacity for repair of damaged articular cartilage is limited.1-4 Arthroscopic lavage, shaving or debridement provide only temporary relief of symptoms and do not stimulate the regeneration of the chondral lesion.5-7 In addition, a recently published, double-blinded, randomised, placebo-controlled trial has shown that arthroscopic lavage and debridement is no better than a placebo procedure.8 Bone marrow stimulation techniques such as subchondral drilling, microfracture and abrasion arthroplasty create a fibrocartilage or hyaline-like cartilage cover that provides less mechanical stability against tear and shear forces.9-11 Transplantation of osteochondral autografts has become a popular and widely accepted technique for treating circumscribed osteochondral lesions. Most clinical studies have concentrated upon the treatment of focal cartilage defects of the knee and ankle joints.12-20 Focal osteochondral lesions of the shoulder are less common than those of the lower extremities. However, they are often symptomatic and, if left untreated, fail to heal and may progress to glenohumeral osteoarthritis. After the encouraging results of osteochondral autologous transplantation in the knee and ankle VOL. 86-B, No. 7, SEPTEMBER 2004 joints we have started to use the osteochondral autologous transfer system (OATS) on patients with full-thickness osteochondral lesions of the shoulder. Our aim was to evaluate the clinical and radiological results of the procedure, as well as its risks. Patients and Methods In a retrospective study we assessed the clinical and radiological results of eight osteochondral autologous transplantations from the knee to the shoulder. The diagnosis was established by history, clinical examination, standard radiographs, magnetic resonance imaging and diagnostic arthroscopy. Inclusion criteria for this study were patients with circumscribed, Outerbridge grade IV,21 osteochondral lesions of the humeral head or the glenoid, an affected area greater than 100 mm2, and no or mild osteoarthritic changes (≤ stage I according to Samilson and Prieto22). Patients with superficial chondral lesions (Outerbridge grades I to III),21 lesions greater than 250 mm2 and advanced radiological signs of glenohumeral osteoarthritis (≥ stage II according to Samilson and Prieto22) were excluded. All patients were informed about the unknown natural course of the osteochondral lesion, the 991 992 M. SCHEIBEL, C. BARTL, P. MAGOSCH, S. LICHTENBERG, P. HABERMEYER Table I. Characteristics of the patients, defects and procedures Patient Gender Age (yrs) 1 M 57 2 M 38 3 4 M M 56 53 5 F 43 6 7 M M 44 23 8 F 31 Aetiology Location* Size of defect Number of cylinders used (mm2) Traumatic anterior instability Traumatic anterior instability Post-traumatic Hyperlaxity Central (h) 120 1 Posteromedial (h) 150 3 Central (h) Posterocentral (h) 105 105 2 2 Anterocentral (g) 128 1 Central (h) Anterocentral (h) 144 250 1 3 Posteromedial (h) 200 2 Traumatic anterior instability Hyperlaxity Traumatic posterior subluxation Traumatic anterior instability Additional procedures performed Labral augmentation, capsular shift None None Labral augmentation, capsular shift Labral augmentation, capsular shift None None Labral augmentation, capsular shift * h, humeral; g, glenoid documented clinical and radiological results of the osteochondral transplantation procedure in the knee and ankle joints, as well as the surgical technique and alternative therapeutic options. Pre- and post-operatively the clinical evaluation included the Constant score for the shoulder and the Lysholm score for the knee joint.23,24 Patients were reviewed at six weeks, six months and one year post-operatively and at the most recent follow-up. The final assessment was performed by an independent examiner and not by the surgeon. Standard radiographs (true anteroposterior, true anteroposterior in external and internal rotation and axillary views) were used to assess the presence of glenohumeral osteoarthritis. Signs of glenohumeral osteoarthritis were graded according to the classification of Samilson and Prieto.22 MRI was performed post-operatively in every patient in order to assess the integrity of the osteochondral grafts. As osteochondral autologous transplantation has not been fully investigated in the shoulder, a second-look arthroscopy six months postoperatively was recommended to all patients, but performed in only two. The remaining patients refused further surgical intervention. Statistical analysis between variables pre- and post-operatively was performed with the Wilcoxon signed-rank test for non-parametric data. The level of significance was set at p < 0.05. The statistical software used was StatView (Abacus Concepts Inc, Berkeley, California). Operative technique. All procedures were performed in the beach chair position under interscalene block and general anaesthesia. A diagnostic glenohumeral arthroscopy was performed using a standard posterior portal. According to the International Cartilage Repair Society the defect was classified on the basis of its location, size, thickness and the condition of the opposing articular surface. In each patient Fig. 1a Fig. 1b Intra-operative findings. A grade IV osteochondral lesion of the humeral head a) before and b) after autologous transplantation with two osteochondral plugs. THE JOURNAL OF BONE AND JOINT SURGERY OSTEOCHONDRAL AUTOLOGOUS TRANSPLANTATION 993 Table II. Clinical results Constant score (pre-operatively) Constant score (post-operatively) Patient Pain ADL* ROM† Follow-up Strength (kg) Total (mths) 1 2 3 4 5 6 7 8 10 10 5 13 12 5 10 5 9 12 10 16 17 14 18 7 38 40 38 30 40 40 40 40 9.7 9.9 8.4 5.0 4.5 3.3 10.4 2.7 77.2 82.6 70.5 69.4 78.4 65.9 89.6 57.6 36 41 47 44 30 24 31 8 Lysholm score Pain ADL ROM Strength (kg) Total Total 15 13 13 15 15 15 15 15 20 18 19 18 20 20 20 18 36 40 40 36 40 40 40 40 10.6 11.1 6.9 6.9 6.0 6.1 9.9 4.7 93.1 94.1 86.3 83.4 87.5 87.7 95.4 82.4 100 100 91 100 100 100 87 64 * ADL, activities of daily living † ROM, range of movement the stage of the osteochondral lesion was Outerbridge grade IV with a mean size of 150 mm2 (105 to 250 mm2). In seven patients the defect was located on the humeral side and in one patient it was on the glenoid side. In three patients the defect was central in position, in three it was posteromedial and in one it was posterocentral on the humeral head. The one glenoid defect was positioned anteromedially (Table I). The transplantation procedure was performed with an osteochondral autograft transfer system (Arthrex, Naples, Florida). The shoulder joint was exposed through a standard deltopectoral approach and the cephalic vein was preserved and retracted laterally. The subscapularis muscle was detached from the lesser tuberosity approximately 0.5 cm from its insertion, and stay sutures were attached for subsequent refixation and the muscle was then retracted medially. If capsular instability was present the subscapularis was stripped from the anterior capsule in order to perform a capsular shift at the end of the procedure. The humeral head was next exposed and the defect was inspected (Fig. 1a). The size of the lesion was again measured using a range of appropriate colour-coded sizers. A recipient socket was then created in order to provide an adequate press-fit graft fixation. The appropriately sized tubular harvester was introduced into the joint and placed over the affected area, taking great care to ensure that the harvester was perpendicular to the articular surface. The decision to transplant single or multiple osteochondral grafts was based upon the size and location of the defect. Either one (three patients), two (three patients), or three (two patients) osteochondral plugs were used in order to fill the defects (Table I). Next, the osteochondral graft was taken. The knee joint was exposed through a lateral miniarthrotomy. The chosen donor site was in an area along the outer edge of the lateral femoral condyle, immediately above the sulcus terminalis. This is a low weight-bearing area and offers a convex articular surface similar to that of the central humeral head.25 The tube harvester was inserted into the joint and placed perpendicular to the selected harvest site. It was then driven into the bone to the same depth as the osteochondral defect and the graft was harvested. The donor cavities were not filled. The harvested grafts VOL. 86-B, No. 7, SEPTEMBER 2004 were then transferred into the prepared recipient site using a press-fit technique (Fig. 1b). In order to address any underlying instability or capsular redundancy an additional labral augmentation (Harryman et al26) and a lateral capsular shift (Matsen et al27) was performed in four patients. Finally, the subscapularis tendon was reattached anatomically with the arm in 30˚ of abduction and 20˚ of external rotation. Post-operative management. Post-operatively, the patients underwent a standard rehabilitation programme. The affected arm was placed in an abduction pillow for three weeks. Passive range of movement was initiated on the third post-operative day and was restricted to 60˚ of flexion, abduction and internal rotation for the first two weeks and then increased to 90˚ up to the five-week point. External rotation was prohibited up to the six-week point in order to protect the reconstructed anterior capsule and subscapularis tendon. Four to six weeks post-operatively the patient started active movements and a muscle strengthening programme. Results The mean age of the patients was 43.1 years (23 to 57). The dominant shoulder was affected in six patients. Full details are summarised in Table I. Clinical. Seven patients were available for medium term follow-up and one for short-term follow-up (Table II). After a mean follow-up of 32.6 months (8 to 47) the overall Constant score improved significantly from 73.9 points (57 to 89.6) to 88.7 points (82.4 to 95.4) (p < 0.05). All patients had less pain when compared with their original pre-operative rating. There was a significant (p < 0.05) increase in the overall pain rating scale from the initial mean score of 8.7 (5 to 13) to the latest follow-up score of 14.5 (13 to 15). Six patients were completely free of pain. The mean activities of daily living (ADL) rate increased significantly (p < 0.05) from 12.9 (7 to 18) to 19.1 (18 to 20). All but two patients achieved their full work and sporting activity levels. The results for range of movement and strength also increased although these were not statistically significant (p > 0.05 for both) and probably due to pain relief. The functional outcome of the knee was graded with the 994 M. SCHEIBEL, C. BARTL, P. MAGOSCH, S. LICHTENBERG, P. HABERMEYER Fig. 2a Fig. 2b Anteroposterior radiograph of a shoulder a) before and b) 24 months after autologous osteochondral transplantation. Note the increase in inferior osteophyte formation between the pre- and post-operative examinations. Lysholm score.24 Six patients had an excellent result (91 to 100 points), one patient had a satisfactory result (77 to 90 points) and one patient had a poor result (0 to 76 points). Full clinical results are shown in Table II. Radiographic. Pre-operatively, four patients had stage I glenohumeral osteoarthritic changes.22 In all but one the osteoarthritis had deteriorated between the pre- and postoperative assessments. The patient who did not progress was only available for short-term follow-up. Four patients did not show any signs of glenohumeral osteoarthritis preoperatively (Fig. 2a). However, by their latest follow-up all four had developed new inferior humeral osteophyte formation (Fig. 2b) although this did not influence the final clinical result. Despite an increase in the size of humeral osteophytes the mean glenohumeral distance did not significantly reduce between the pre-operative (4.4 mm) and post-operative (4.2 mm) examinations (p > 0.05). MRI, which was performed in the paracoronal, transaxial and parasagittal planes, revealed excellent graft viability and congruence of the chondral surfaces (Fig. 3) in all but one patient. In one patient, signs of transplant insufficiency with evidence of avascular necrosis could be seen. However the patient was clinically asymptomatic and satisfied with the post-operative result. Full radiographic results are shown in Table III. Second-look arthroscopy. In two patients a second-look arthroscopy (Table III) was performed six months postoperatively in order to assess the chondral surfaces. In both there was good macroscopic integration of the grafts with Fig. 3 Post-operative paracoronal MRI, 24 months after autologous osteochondral transplantation showing an intact osteochondral plug and a congruent articular surface. the original osteochondral defect being completely covered by chondral tissue (Fig. 4). The surrounding chondral surface showed some superficial fissuring, representing a grade I chondral lesion according to Outerbridge.21 Complications. No complications which could be directly related to the surgical procedure in the shoulder were seen. THE JOURNAL OF BONE AND JOINT SURGERY OSTEOCHONDRAL AUTOLOGOUS TRANSPLANTATION 995 Table III. Staging, radiographic, MRI and arthroscopic results Stage of osteoarthritis18 Glenohumeral distance (mm) Patient Pre-operative Post-operative Pre-operative Graft integrity on Post-operative MRI Graft integrity at second-look arthroscopy 1 2 3 4 5 6 7 8 I I None None None I None I II II III II I II I I 5 4 4 3 5 3 5 5 Congruent surface Not performed Not performed Not performed Not performed Not performed Congruent surface Not performed 5 4 4 4 5 3 5 5 However, one patient reported persistent pain and recurrent effusions of the donor knee. This patient achieved a poor Lysholm score result (< 75 points) by their latest follow-up. Because of donor site morbidity the patient underwent two revision arthroscopic surgical procedures with debridement of the knee joint. Although the shoulder was completely painless eight months post-operatively the patient was dissatisfied with the procedure and was unavailable for medium-term follow-up. Intact Intact Intact Avascular necrosis Intact Intact Intact Intact Osteochondral lesions of the shoulder are less common than those of the lower extremity but can cause considerable symptoms. These might include joint pain, effusion and mechanical dysfunction. Although the natural history of isolated osteochondral defects has not been well defined, clinical experience has shown that these lesions may progress to symptomatic degeneration of the joint. Consequently, the treatment of selected, isolated, articular cartilage lesions may delay or prevent the development of osteoarthritis. The aim of all methods of articular cartilage restoration is to reproduce the mechanical, structural and biochemical properties of the original hyaline articular surface. Although different studies have reported good and excellent clinical results from autologous chondrocyte implantation (ACI), osteochondral autograft transplantation is currently the only technique that appears to maintain the characteristics of hyaline cartilage.15,16,28-30 Bobic13 stated that the main reason for the long-term survival of transplanted hyaline cartilage was the preservation of an intact tidemark and cancellous bone barrier. Transplantation of articular cartilage as a part of an osteochondral graft has been shown to be an effective method of replacing focal areas of damaged articular cartilage and reducing pain in both the knee and ankle joints.12-20 Our study shows that osteochondral transplantation from the knee to the shoulder results in a good clinical outcome in terms of pain relief and functional recovery. We observed a significant increase in the overall Constant score between the pre- and post-operative assessments. At their latest follow-up, all but two of our patients were com- Fig. 4a Fig. 4b Discussion Arthroscopic view of a grade IV osteochondral lesion a) before and b) six months after autologous transplantation. VOL. 86-B, No. 7, SEPTEMBER 2004 996 M. SCHEIBEL, C. BARTL, P. MAGOSCH, S. LICHTENBERG, P. HABERMEYER pletely pain-free and able to perform all activities of daily living. Two patients had even returned to overhead sports activities. It is important to understand that the functional results which our patients obtained are not only due to the osteochondral transplantation procedure but also to the correction of the underlying and additional glenohumeral pathology. In four patients with recurrent instability of the shoulder a capsular shift with labral augmentation was performed. It is significant that in all of our patients glenohumeral osteoarthritic changes were present at their latest followup. Although the glenohumeral distance on the anteroposterior radiograph did not change significantly, inferior osteophyte formation was seen in all patients. For those who had stage I osteoarthritis pre-operatively, all but one showed a significant deterioration between the pre- and post-operative assessments although this was never by more than one stage. The one patient who did not progress was only available for short-term follow-up. Four patients had no signs of glenohumeral osteoarthritis pre-operatively. However, by their latest follow-up all had developed new, inferior humeral osteophyte formation. Despite this, these osteoarthritic changes did not correlate with either postoperative pain or the final post-operative result. This progression in glenohumeral osteoarthritis still poses the question as to whether osteochondral transplantation may slow down the development of symptomatic glenohumeral osteoarthritis at all. In all but one patient MRI follow-up revealed excellent graft viability and congruence of the chondral surfaces. In one patient there were signs of graft insufficiency, probably due to avascular necrosis. However, this patient was pain-free and very satisfied with the result. The potential disadvantages of this technique include donor site morbidity, a limited supply of grafts, dead space between circular grafts, graft integration and the different mechanical properties and geometry between donor and recipient hyaline cartilage.2-4 Donor site morbidity is perhaps the most important risk factor when performing an osteochondral transplantation from the knee to the shoulder. Studies have shown that donor sites normally refill with cancellous bone and fibrocartilage and do not cause significant problems.13,19,31 However, persistent pain and recurrent effusions of the donor knee were seen in one of our patients. Although the shoulder was pain-free the patient required two revision arthroscopic procedures. Donor site morbidity can clearly be a serious problem and must be taken into consideration when counselling a patient for an osteochondral transplantation from the knee to the shoulder. The ideal osteochondral defect for an osteochondral autologous transplantation in the shoulder is relatively small, perhaps 10 to 20 mm in diameter.13 In our study group the mean size of the affected area was 150 mm2 (105 to 250). Large osteochondral defects are not suitable for this technique as osteochondral grafts are limited and it is also technically difficult to reconstruct a large subchondral defect. A large number of grafts may also lead to instability in the transplantation area. Other problems with this technique are differences in the thickness, biomechanical composition and mechanical properties of the articular cartilage of the knee joint when compared with the shoulder. Although we experienced no difficulties in performing this procedure, the final clinical results may be very technique-dependent. There are many peri-operative pitfalls that need to be considered. In particular, an appropriate length of graft is essential to a successful outcome. If too long or too short, an osteochondral cylinder can lead to incongruity of the articular surface. Also, if the graft is not inserted in an orthograde fashion an adequate press-fit cannot be achieved which may lead to loosening or failed integration. Our study has certain limitations. It includes only a small number of patients so that statistical analysis is restricted. Despite this, to our knowledge it is the first study to document the medium-term clinical and radiographic results for patients with full-thickness cartilage lesions of the shoulder who have been treated by osteochondral autologous transplantation. It must also be remembered that not all of the patients had the same aetiology for their osteochondral defect. Finally, in three patients the associated underlying pathology was also corrected which must be taken into account when interpreting the clinical results. In summary, osteochondral autologous transplantation in the shoulder appears to offer good clinical results for the treatment of osteochondral lesions of the glenohumeral joint. However, the results of our study suggest that the development of osteoarthritis and the progression of preexisting osteoarthritic changes cannot be altered by the technique. No benefits in any form have been received or will be received from a commercial party related directly to the subject of this article. References 1. Buckwalter JA, Mankin HJ. Articular cartilage. Part I: tissue design and chondrocyte-matrix interactions. J Bone Joint Surg [Am] 1997;79-A:600-11. 2. Buckwalter JA, Mankin HJ. Articular cartilage: II: degeneration and osteoarthrosis, repair, regeneration and transplantation. J Bone Joint Surg [Am] 1997;79-A: 612-32. 3. Mandelbaum BR, Browne JE, Fu F, et al. Articular cartilage lesions of the knee. Am J Sports Med 1998;26:853-61. 4. Newman AP. Articular cartilage repair. Am J Sports Med 1998;26:309-24. 5. Baumgaertner MR, Cannon WD Jr, Vittori JM, Schmidt ES, Maurer EC. Arthroscopic debridement of the arthritic knee. Clin Orthop 1990;253:197-202. 6. Jackson RW, Marans HJ, Silver RS. Arthroscopic treatment of degenerative arthritis of the knee. J Bone Joint Surg [Am] 1988;70-A:332. 7. Weinstein DM, Bucchieris JS, Pollock RG, Flatow EL, Bigliani LU. Arthroscopic debridement of the shoulder for osteoarthritis. Arthroscopy 2000;16:471-6. 8. Moseley JB, O’Malley K, Petersen NJ, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002;347:81-8. 9. Childers JC Jr, Ellwood SC. Partial chondrectomy and subchondral bone drilling for chondramalacia. Clin Orthop 1979;144:114-20. 10. Insall J. The Pridie debridement operation for osteoarthritis of the knee. Clin Orthop 1974;101:61-7. 11. Johnson LL. Arthroscopic abrasion arthroplasty historical and pathological perspective: present status. Arthroscopy 1986;2:54-69. THE JOURNAL OF BONE AND JOINT SURGERY OSTEOCHONDRAL AUTOLOGOUS TRANSPLANTATION 12. Al-Shaikh RA, Choul LB, Mann JA, Dreeben SM, Prieksorn D. Autologous osteochondral grafting in the knee: indication, results, and reflections. Foot Ankle Int 2002;401:170-84. 13. Bobic V. Arthroscopic osteochondral autograft transplantation in anterior cruciate ligament reconstruction: a preliminary clinical study. Knee Surg Sports Traumatol Arthrosc 1996;3:262-4. 14. Gautier E, Kolker D, Jakob RP. Treatment of cartilage defects of the talus by autologous osteochondral grafts. J Bone Joint Surg [Br] 2002;84-B:237-44. 15. Hangody L, Fules P. Autologous osteochondral mosaicplasty for the treatment of full-thickness defects of weight-bearing joints: ten years of experimental and clinical experience. J Bone Joint Surg [Am] 2003;85-A(Suppl 2):25-32. 16. Hangody L, Kish G, Karpati Z, Eberhart R. Treatment of osteochondritis dissecans of the talus: use of a mosaicplasty technique: a preliminary report. Foot Ankle Int 1997;18:628-34. 17. Hangody L, Kish G, Karpati Z, Szerb I, Udvarhelyi I. Arthroscopic autogenous osteochondral mosaicplasty for the treatment of femoral condylar articular defects. Knee Surg Sports Traumatol Arthrosc 1997;5:262-7. 18. Jakob RP, Franz T, Gautier E, Mainil-Varlet P. Autologous osteochondral grafting in the knee: indication, results, and reflections. Clin Orthop 2002;401:170-84. 19. Morelli M, Nagamori J, Miniaci A. Management of chondral injuries of the knee by osteochondral autogenous transfer (mosaicplasty). J Knee Surg 2002;15:185-90. 20. Sammarco GJ, Makwana NK. Treatment of talar osteochondral lesions using local osteochondral graft. Foot Ankle Int 2002;23:693-8. 21. Outerbridge RE. The etiology of chondromalacia patellae. J Bone Joint Surg [Br] 1961;43-B:752-7. VOL. 86-B, No. 7, SEPTEMBER 2004 997 22. Samilson RL, Prieto V. Dislocation arthropathy of the shoulder. J Bone Joint Surg [Am] 1983;65-A:456-60. 23. Constant CR, Murley AH. A clinical method of functional assessment of the shoulder. Clin Orthop 1987;214:160-4. 24. Lysholm J, Gillchist J. Evaluation of knee ligament surgery with special emphasise on use of a scoring scale. Am J Sports Med 1982;10:150-4. 25. Simonian PT, Sussmann PS, Wickiewicz TL, Paletta GA, Warren RF. Contact pressures at osteochondral donor sites in the knee. Am J Sports Med 1998;26:491-4. 26. Harryman DT, Ballmer FP, Harris SL, Sidles JA. Arthroscopic labral repair to the glenoid rim. Arthroscopy 1994;10:20-30. 27. Matsen FA III, Lippitt SB, Sidles JA, Harryman II DT. Practical evaluation and management of the shoulder. Philadelphia: WB Saunders. 1994. 28. Bentley G, Biant LC, Carrington RW, et al. A prospective, randomised comparison of autologous chondrocyte implantation versis mosaicplasty for osteochondral defects in the knee. J Bone Joint Surg [Br] 2003;85-B:223-30. 29. Horas U, Pelinkovic D, Herr G, Aigner T, Schnettler R. Autologous chondrocyte implantation and osteochondral cylinder transplantation in cartilage repair of the knee joint: a prospective, comparative trial. J Bone Joint Surg [Am] 2003;85-A: 185-92. 30. Romeo AA, Cole BJ, Mazzocca AD, et al. Case report: autologous chondrocyte repair of an articular defect in the humeral head. Arthroscopy 2002;18:925-9. 31. Ahmad CS, Guiney WB, Drinkwater CJ. Evaluation of donor site intrinsic healing response in autologous osteochondral grafting of the knee. Arthroscopy 2002;18: 95-8.