Advantages: Cost-effective; technically feasible; supportive
clinical data; does not preclude the subsequent use of other techniques.
Disadvantages: Does not reliably produce hyaline cartilage.
Clinical Data: Dr.Steadman reported clinical trials of
microfracture in humans documenting improvement of symptoms and function
in 364 of 485 patients (75%) followed prospectively for an average of
Laboratory Data: Dr. Myron Spector reported that chondral
defects treated with microfracture fill completely with fibrocartilage
at 3 months in an animal model. Dr. Steadman and colleagues at the Steadman
and Hawkins clinic in Vail, Colorado used microfracture to treat full
thickness cartilage defects in horses. At 4 weeks the defects were 90-100%
filled, with histology indicating 30% hyaline cartilage at 8 months
and 42% at 12 months.
Recommended Technique: The surgeon should debride the
chondral defect to a stable articular margin. The base of the defect
should be debrided through the calcified cartilage layer. Three to four
perforations per square centimeter should be made, starting with circumferential
perforations at the perimeter of the defect. Postoperatively, the patient
should be treated with early controlled motion and limited weight bearing
for six weeks.
Osteochondral Autograft Transplantation (OATS or Mosaicplasty)
Advantages: Potentially high survival-rate of articular
chondrocytes; appears to maintain hyaline cartilage characteristics.
Disadvantages: Donor site morbidity, limited supply
of grafts, and long rehabilitation. The results of this method of treatment
may be very technique dependent. The technique is most suitable for
smaller defects. There is no truly non-weight-bearing portion of the
articular surface. Malleting the plug in to place may cause articular
Clinical Data: Dr. R.A. Gambardella from the Kerlan-Jobe
Orthopaedic Clinic reported 43% good results at 18 months, noting that
outcomes were adversely affected by patella-femoral chondromalacia and
uncorrected mechanical axis. L. Hangody reported an HSS knee score of
82 in 168 patients at 18 month to 5 year follow-up. Repeat arthroscopy
with biopsy and histological analysis in 33 patients showed donor sites
filled with fibrocartilage. The transplanted cartilage appeared to retain
its hyaline cartilage characteristics and showed deep matrix integration.
Other investigators reported satisfactory results in upwards of 86%
in the short term: Imhoff and colleagues from the University of Munich,
Germany reported 90% satisfactory results with 3-20 month follow-up;
Gautier and Jakob from the Kantonsspital, Fribourg, Switzerland, 86%
at 2 years; and Magnani from Bologna, Italy, 94% with 3-12 month follow-up.
Complications included fracture or folding of the trephine tip, fracture
of the osteochondral plug, anterior knee pain, and postoperative hematoma.
Laboratory Data: Dr. G.A. Paletta Jr. evaluated the OATS
procedure in a dog model with histological and biomechanical evaluation
at 24 weeks follow-up. The hyaline cartilage did not integrate with
the surrounding tissue, a tidemark was present and there was surface
irregularity. The plugs showed decreased viable chondrocytes and increased
stiffness. H.U. Staubli from the Tiefenauspital, Bern, Switzerland and
co-workers assessed patella-femoral contact zones and concluded that
the best site for harvest of osteochondral plugs is the superior medial
margin of the femoral notch. They recommend avoiding the superior lateral
aspect of the femoral trochlea.
Recommended Technique: Drs. Gautier and Jakob recommend
this technique for chondral lesions between 1.5 and 3.0 square centimeters
in size; Drs. Hangody and Imhoff use the technique for lesions as large
as 8.5 and 7.0 square centimeters respectively.
Autologous Chondrocyte Implantation (ACI)
Advantages: Potential for restoration of normal hyaline
Disadvantages: Two procedures required including an
arthrotomy; expensive; laboratory support required; highly technique
dependent; unpredictable results for the patella-femoral joint.
Clinical Data: An update on the largest ongoing series
by Dr. L. Peterson and colleagues from Gothenburg, Sweden included clinical,
arthroscopic, and histological evaluation. They subcategorized their
results by lesion location, type, and instability. Satisfactory results
at 2 to 9 years follow-up were achieved in 80% of patients overall:
90% for femoral condyle lesions; 74% for femoral condyle lesions with
simultaneous ACL reconstruction; 84% for osteochondral defects; 69%
for patellar lesions; 58% for trochlear lesions; and 75% for multiple
defects. On follow-up arthroscopic evaluation, they used a 12 point
system to grade healing of the lesion: they allotted 4 points each for
defect fill, integration of the border, and macroscopic appearance.
They reported a score of 10.3 in isolated lesions, 10.9 in ACL reconstructed
knees, and 10.5 in osteochondral defects. Biopsies of the repair tissue
were obtained in 37 patients. The presence of hyaline-like repair tissue
correlated with a satisfactory clinical result. They reported a 19%
failure rate based upon histological criteria.
Dr. Tom Minas reported his results in subsets of simple and complex
lesions with satisfactory results of 63% at 1-year follow-up and 100%
at 2-year follow-up in a small cohort of complex lesions. In salvage
procedures, the rate of satisfactory results was 78% at one year and
100% at two years. Specific complications reported by Dr. Minas included
detachment of the periosteal graft (11%), adhesions (10%), hypertrophic
periosteal patch (10%), treatment failure (7%), and DVT (1.4%).
Dr. B.P. McKeon from the New England Baptist Hospital in Boston reported
satisfactory results in 100% of patients at 13 months; Dr. A. Lindahl
and colleagues from Gothenburg University in Sweden, 100% at 52 months;
Drs. Hart and Paddle-Ledinek from Monash University in Melbourne Australia,
100% at 9 months. Dr. Georgoulis and co-workers reported pain relief
in all patients. Dr. D.R. Turgeon from Presbyterian Hospital in Dallas,
Texas reported 80% clinical improvement and 75% patient satisfaction
at 1-year follow-up. The only dissenting data were from Koh and colleagues
at the Hospital for Special Surgery who reported failure in 8 of 14
Laboratory Data: Dr. Myron Spector reported 50% filling
of a focal defect at 3 months in an animal model. Histologic and gross
results deteriorated at 12-18 months. Dr. A. Lindahl reported hyaline-like
tissue in 73% of specimens 52 months following ACI.
Technique Recommendations: The technique is not indicated
in osteoarthritis, and should be used with caution in the patello-femoral
joint. It may be best to reserve this technique for patients in whom
conventional techniques have failed. The following lesion size specifications
were recommended: A. Georgoulis: 3.0 to 8.0 square centimeters; B.P.
McKeon: 1.2 to 18.0 square centimeters; Sandelin from Helsinki, Finland:
2.0 to 20.0 square centimeters; and A. Scorrano from Belluno Hosptial
in Italy, 2.2 to 21.0 square centimeters.