We report our experience with osteochondral autogenous cartilage
transfer for osteochondral defects in the knee joint in five
patients. They were followed up for over a year. Suitability for
this procedure was assessed by arthroscopy and knees with focal
cartilage defect of 1.5cms or less were selected. Associated
intra-articular pathology if any was recorded and treatable
lesions like meniscal tears and lateral retinacular tightness
were attended to at the same time. The osteochondral autologous
transplantation (O.A.T.S) procedure was performed as an open
procedure at a second sitting.
The patients were mobilized non-weight bearing with crutches for
six weeks post-operatively allowing flexion up to 90 degrees and
quadriceps exercises. An independent observer performed the
evaluation before and after the procedure using the modified
knee scoring system of the Hospital for Special Surgery. The pre
and post-op scores were compared. As the knee function in terms
of range of movements, stability and alignment was good
pre-operatively, most patients did not show striking
improvements in these modalities.
Severe pain scoring zero on the pain scale improved to ‘mild or
occasional’ scoring 45/50 in three patients. One patient
reported marginal and one, no improvement in pain. The walking
distance improved considerably; unlimited walking distance in
three patients (scoring 50/50) and one patient graduated to
walking five to ten blocks (scoring 30/50). One patient reported
Two patients who scored zero with inability to do stairs had
progressed to ‘normal up & down’ (scoring 50/50) and, ‘normal
up, down with rails’ (scoring 30/50) respectively. Two patients
who could climb up and down with rails (scoring 30/50)
pre-operatively reported to do so un-aided (scoring 50/50) after
surgery. There were few minor complications in the way of
swelling (2), haemarthrosis (1) and pain (1), which settled down
Key words: Osteochondral defect, knee joint, cartilage
Articular cartilage defects are not uncommon
and has been reported widely in literature. These defects have a
poor capacity to heal. They are the forerunners of further
degeneration and osteoarthritis in the joint. There has been no
effective treatment option until recently. Effective treatment
of these defects could lead to postponement of knee degeneration
and delay extensive procedures like knee replacement to a
significant degree. The treatment options are debridement and
drilling( 1),micro fracture, cartilage transfer(cadaveric/
allograft/autograft) and transfer of cultured cartilage cells
into defects. There is advantages and disadvantages with each
Debridement of defects leads to healing with
fibro cartilage, which is liable to fail to compressive forces
in the long term. Cadaveric allograft transfer and cultured
cartilage transfer are technically complicated and require
laboratory facilities. The Osteochondral autologous cartilage
transfer system (O.A.T.S) technique offers a dual advantage of
transferring true hyaline cartilage to the defect on a bone base
and being technically simpler and more feasible with the average
orthopaedic practice. Here we report our early experience of
Method and materials
This prospective case series study was
undertaken at King’s Mill Hospital between August 1999 and June
2001.The patients selected for this study were among those who
presented with complaints of knee pain and difficulty mobilizing
at the out-patients clinic.
Those who had a full thickness medial femoral
condylar cartilage defect of 1.5cms or less at arthroscopy were
deemed suitable for this procedure. Multiplicity of defects was
not considered a contraindication as long as the defects were
focal in nature.
Larger defects greater than 1.5cms in
diameter and bilateral knee defects were excluded from the
The defects were present in the central
weight bearing area of the femoral condyle.Potential donor sites
were identified and recorded at the initial arthroscopy.
Accompanying intra-articular pathology if any was recorded and
treatable lesions like meniscal tears and lateral retinacular
tightness were dealt with at the same time.
The patient was explained about this
procedure in detail at the clinic visit with an information
sheet explaining the complications of this procedure. The
modified knee scores of the Hospital for Special Surgery was
assessed during this visit. On the day of the operation, the
procedure details was explained and an informed written consent
was obtained. The patient demographics and indications for the
surgery was entered on to a preformed sheet.
The transfer was performed as an open
procedure by the senior author(PJL) under general anaesthesia
with tourniquet control. The knee was opened by a standard
anterior midline incision with medial para-patellar approach
with eversion of patella.
The dimensions of the defect was confirmed
and graft harvested from the donor site which was usually the
outer edge of the lateral femoral condyle using ‘Protec’ tubular
osteochondral harvesters specially designed for this purpose.
The recipient area was curetted out and cancellous bone
harvested. The donor graft was inserted into the defect and
impacted firmly. The cancellous bone harvested from the
recipient area was then inserted into the donor defect and
The knee was closed with a drain in the knee joint and
Post-operatively, all the patients were kept
non-weight bearing for six weeks . Physiotherapy was started the
next day ;initially continuous passive motion followed by active
knee mobilization and quadriceps exercises added after the
post-operative pain and swelling subsided. Patients were
discharged from hospital on the second or third post-operative
day and followed up in clinic.
All the patients in this case series were
evaluated by an independent observer and rated using the
modified knee scoring system from the Hospital for Special
Surgery( ).This system is subjective as well as objective and
evaluates the knee not only in terms of movements and
instability but also its function in terms of pain and ability
to walk or climb stairs. Post-operative scores were matched
against pre-operative scores an attempt made to objectively
assess recovery in individual patients.
This case series included five patients who underwent the
O.A.T.S procedure by the senior author.Incidently all five
patients were male. The mean age was 36 years (range 28 – 45
years) and all were unilateral (3 right side defect and 2 left
Two patients had a history of road traffic accidents
involving the knees of which one had an undisplaced fracture of
the patella, which healed well with conservative treatment. Two
patients had a history of twisting injury during sports of which
one had a ruptured anterior cruciate ligament. One patient had
no preceding history of trauma but was grossly overweight.
Most patients( 4/5) presented with pain in the knee and
restriction of activities as the predominant compliant. They had
remarkably good range of knee movements( 0 – 120 degrees of
flexion) except for one patient who had flexion restricted to 90
degrees. All the knees were stable except for the knee with
cruciate ligament rupture. on had flexion contracture or
extensor lag and all the knees were well aligned.
The pre-operative knee scores were good in terms of range of
movements, stability and alignment, but the functional scores
were very low and all patients revealed gross restriction in
ability to walk and climb or descend the stairs.
Only one patient had an anterior cruciate ligament rupture in
our series. This was reconstructed with a bone-patella-tendon
autograft done at the same time as the O.A.T.S procedure. One
patient had a bucket handle tear of the lateral meniscus, which
was resected at arthroscopy while one had a tear of the
posterior horn of medial meniscus, which was trimmed. Three
patients were noted to have grade two arthritic changes in the
As the knee function in terms of range of movements,
stability and alignment was good pre-operatively, most patients
did not show striking improvement in these modalities
post-operatively. None of the knees had decreased range of
movements, instability or mal-alignment post-operatively.
Pain: There was a vast improvement in the pain scores.
Three patients who reported severe pain scoring zero on the pain
scale pre-operatively improved to ‘mild or occasional pain’
scoring 45/50.One patient reported marginal and one, no
improvement in pain.
Stairs: Two patients who were unable to climb or
descend stairs and had scores of zero progressed to,’ normal up
& down’(50/50) and ,’normal up, down with
rails’(30/50)respectively. Two patients who could climb up and
down with rails(30/50) pre-operatively reported their ability to
do so un-aided(50/50) after surgery. One patient had little
improvement in stair climbing and graduated from ‘up with rails,
no down’(15/50) to,’ up and down with rails’(30/50).
Walking distance: Of the three who were walking five
to ten blocks pre-operatively scoring 30/50, two could walk
unlimited(50/50) while one reported no change in his
pre-operative status. Of the two patients who could not walk
more than five blocks scoring 20/50 pre-operatively, one could
walk an unlimited distance scoring 50/50 while the other
graduated to walking five to ten blocks scoring 30/50.
There were no major complications in our series. Two patients
had joint swelling after exertion, which has settled down. One
patient reported with haemarthrosis at one month post-op, which
was aspirated and settled down without recurrence.
Post-operative pain settled down in three weeks.
The treatment of articular cartilage defects in the knee has
been a much-debated topic in the last few years. It has been
theorized that the filling out of these defects with
physiologically efficient tissue will postpone widespread
degeneration. This may help delay joint replacement procedures.
Brittberg et al have demonstrated autologous transfer of
chondrocytes from an uninvolved portion of the knee into the
defect to be effective in forming viable hyaline cartilage.
Wakitani et al went a step ahead and transferred cultured
primary mesenchymal cells into the defect in rabbits. The
transferred cells were demonstrated to differentiate into
cartilage and bone.
Allograft cartilage transfer from cadavers has also been
demonstrated to be effective and the results have been
encouraging in the short term. Bobic has demonstrated core
grafting in ACL deficient knees and reported good results with a
two year follow-up. This technique has the advantage of being
the most feasible and technically simple of all the above
Our operative procedure was similar to the one described by
Bobic. It varied from Bobic’s procedure in that it was an open
procedure and the patients were kept non-weight bearing for six
weeks post-operatively. Although Bobic describes the medial
condylar defect as a common finding in ACL deficient knees, only
one of our five patients was found to be ACL deficient. We also
found the defect to co-exist with medial and lateral meniscal
The most important post-operative finding in our study was
the dramatic drop in pain levels. Walking distance and climbing
stairs improved considerably. The one patient who did not
improve his walking distance, climbing stairs and pain relief
was grossly over-weight and has symptoms for eight years prior
to this surgery indicating perhaps an improper choice of
candidate rather than failure of technique. The absence of any
major complications indicate that this is fairly safe procedure
for selective defects under normal circumstances.
Our study confirms the results of this procedure to be
reasonably good in the short term for selective defects. Further
follow-up is required to understand the duration by which the
transplanted cartilage can effectively postpone further
degeneration of the joint. The fate of the transferred cartilage
in the long term also requires close follow-up.
Bobic recommended a second look arthroscopy and/or MRI
scanning as means of further follow-up to assess the cartilage
integration and this should be considered. Careful patient
selection is necessary for the success of this procedure.
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