Revision operations demonstrate that incorrect positioning of the drilling tunnels is the most frequent source of error in unsuccessful cruciate ligament therapy.  Many authors (Päßler, Stäubli and others) recommend obligatory x-ray monitoring of the placement of the Kirschner wires.  However, this represents a significant obstacle to the progress of the operation in many surgical departments.  Many out-patient operating centres do not have image intensifiers (C-arms) available.  It is certainly true that many experienced surgeons can achieve good results relying on their experience and suitable targeting equipment.  However, a statistic in Germany shows that 70% of all cruciate ligament operations are performed by surgeons who perform fewer than 30 replacements per year.  This cannot in any way be considered as constituting adequate experience.

Increasingly, attempts are being made to replace the C-arms with computerised navigation as an aid to surgery. In my opinion, performing this operation with robotic equipment is not the right solution, since the robot does not appropriately take account of and protect many anatomical structures, such as the pes anserinus and the posterior cruciate ligament, during the surgical procedure.

This paper describes navigational assistance for laying the drilling tunnels.  Firstly, landmarks are entered in the operating theatre on normal x-ray images for system orientation. Then corresponding points in the knee joint are palpated.  These are the tibial anterior margin, PCL, the medial and lateral fossa wall, the anterior edge, the anterior horn of the lateral meniscus, the connecting line between the anterior horn of the lateral meniscus and the medial intercondylar eminence as well as the anterior edge of the fossa.  The tibial tuberosity and the dorsal limit of the  tibial head at the height of the posterior horn of the medial meniscus are also palpated.  The position of the tibial targeting device is monitored via infra-red cameras, so that the tibial exit point in the tibial plateau can be established with certainty.

In navigation of the femur, the posterior edge of the fossa and the 10 and  11 o’ clock positions (or the 1 and 2 o’ clock positions respectively) are determined first, followed by the anterior rim of the fossa, in order to make certain here too of hitting the anatomical attachment point of the anterior cruciate ligament on the femur.

After extensive trials, computerised navigation of targeting equipment has proved to be a good aid even for the experienced surgeon.  Once the learning curve has been passed, the extra time required is less than 5 minutes. The radiologically documented reliability of the navigation procedure is now 100% (N = 93, status 03/01).

  K Willits,  A Kirkley, L Thain, A Spouge, PJ Fowler

MRI Analysis of Anatomic Variables  in the Etiology of  Anterior Cruciate Ligament Injury in Female Athletes

            Purpose:            Anterior cruciate ligament rupture rate is two to eight times higher in females than males participating in equivalent competitions, but the etiology remains poorly understood. The purpose of this study was to determine if there are anatomical variables which predispose female athletes to ACL injury. 

Methods:            An anatomical cohort study compared twenty ACL injured subjects aged 18-40 to twenty uninjured subjects matched for age, sex and activity level. MRI imaging was performed of the non-injured knee of the ACL injured cohort, and the matched knee in the uninjured cohort.  All scans were interpreted by two musculoskeletal radiologists blinded to subject group.  Parameters analyzed included ACL area, length and position, femoral notch width and area, and tibial slope.  Student’s t-test and Bonferroni correction compared results for the two groups. A cadaveric validation study assessing the measurement technique will be performed as a separate component of the investigation.

Results:            There were no significant differences between groups in femoral notch dimensions and tibial slope. ACL area, measured at the ACL/PCL cross section was significantly smaller in the ACL group (p = .007). Similarly, the ACL group had significantly smaller patellar tendon cross sectional area (p = .037). Also statistically significant, the intercondylar roof distance  was larger (p = .035) and the ACL length  greater in the ACL group (p = .02).

Discussion & Conclusion:            In contrast to previous studies which concentrate on bony anatomy, these results provide new information suggesting  that inherent morphological differences in the ACL itself, rather than bony anatomy, may be a significant factor in injury etiology.

Significance:            The study suggests that inherent morphological differences in the ACL itself, rather than bony anatomy, may be significant factors in the etiology of ACL injury, which has implications for prevention and treatment

Over 20 years ago Feagin and Curl reported on the diagnosis and treatment of isolated ACL tears.  The purpose of this study is to provide long-term follow-up of this group of patients.

METHODS:  The original 64 patients studied were contacted by mail and asked to respond to a questionnaire that included details of their operation, subsequent operations, Lysholm score, IKDC subjective scores and SANE rating.  This is a preliminary report of the findings to date.

RESULTS:  Currently, 14 patients have responded.  Their average age at the time of the ACL repair was 19.8 (range: 18-22) years, and the average time to follow-up was 31.6 (29.4-35.5) years.  All but 3 patients had subsequent operations to the same knee, and 4 of 14 had operations to address persistent instability of the knee.  The average Lysholm score was 67.1 (24-100) and average SANE score was 63.1 (20-100).  IKDC subjective ratings were 2 normal, 5 near normal, 6 abnormal and 1 severely abnormal.  At final follow-up 11 patients indicated that they continued to have knee instability symptoms.

The purpose of this report is to provide prospective data on the incidence of ACL tears in an athletic college-aged population, and identify any gender differences.

METHODS:  From 1990 to 2000, U.S. Military Academy cadets had their musculoskeletal injury data collected prospectively.  The classes of 1994-2000 were included in this study.  Orthopaedic surgeons during daily clinic and training room evaluations evaluated all cadet knee injuries.  Outpatient visits and admissions, and the activity during which the injury occurred were entered into a database. Complete ACL tears were identified by physical examination and subsequent confirmation at arthroscopy.

RESULTS:  Patients injured ranged in age from 17 to 24.  The average class size was 1096 (range: 1190 for ’94 to 1015 for ‘99), with 959 (1045-912) males and 139 (165-114) females.  There were 232 ACL injuries in the 7 classes (average 33.1 ACLs/ class).  The greatest number of injuries occurred during varsity football and intramural football, with 35 and 34 injuries, respectively.  The average number of ACL injuries/class was 32.3 (8-42) for males and 3.7 (1-9) for females.   Based on these six classes, the probability of sustaining a complete ACL tear during four years at this institution is 0.030; 0.031 for males and 0.027 for females.

ACL INJURIES BY ACTIVITY (males/females)

DISCUSSION:  These data suggest that in a population involved in strenuous activities there is little difference in the incidence of complete ACL tears between men and women.  Explanations for the discrepancy with other recent studies include the high injury rates seen with football, biased selection of athletes for this institution and similar physical training conditions and standards for men and women.

  COL JOHN M. UHORCHAK, MD

RISK FACTORS ASSOCIATED WITH NON-CONTACT ACL INJURY: A PROSPECTIVE FOUR-YEAR EVALUATION OF 859 WEST POINT CADETS.

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COL CHARLES SCOVILLE, MPT

GLENN WILLIAMS MPT

COL(ret) ROBERT A ARCIERO, MD

LTC PATRICK ST PIERRE, MD

LTC DEAN C. TAYLOR, MD

HYPOTHESIS: The purpose of this study was to prospectively evaluate several physical and radiographic parameters that may be associated with non-contact ACL injuries. 

METHODS: Initially, 1198 United States Military Academy cadets (1,021 males and 177 females) consented to participate in this study.  They underwent physical examinations including bilateral knee ligamentous examinations, generalized ligamentous laxity testing, flexibility testing, strength testing and bilateral standardized tunnel radiographs.  From the radiographs the notch width (NW); notch width index (NWI=notch width /condylar width); eminence width (EW); eminence width index (EWI=eminence width/tibia width) and the NW/EW ratios were measured.  The EW and EWI provide an indirect measure of ACL size.  The NW/EW ratio provides an indirect assessment of space available for the ACL relative to the ACL size.  All subjects were involved in strenuous athletic activity at the intercollegiate, club or intramural level.  Orthopedic surgeons during daily clinic and training room evaluations identified all cadets sustaining ACL injuries.  Cadets with incomplete tears, previous injuries and those not completing the four-year program were excluded from the study. 

STASTICAL ANALYSIS:   Pearsons Chi Squared analysis was performed on all categorical variables.  T-Tests were used to compare continuous variables for ACL injured vs. non-injured participants.  Risk ratios were calculated on categorical variables to assess the magnitude of risk associated with specific variables.  Multivariate analysis was accomplished through logistic regressions.  Significance was set at P £ 0.05 for all study parameters.

RESULTS:  The graduating class of 859 cadets (739 males, 120 females) sustained 24 non-contact ACL injuries (16 males, 8 females).  The following associations were statistically significant:  in female cadets ACL injuries were associated with 5 or more of the 8 signs of hyperlaxity, weight >68 kilograms and a body mass index >24.7;  in both male and females the NW, EW, NWI, EWI and NW/EW ratios (females only) were associated with ACL injuries.  No other measures studied were found to be associated with ACL injury in this population.
CONCLUSIONS:   The lower quartile of NWs: (less than 15mm in males, less than 13mm in females) were associated with a risk ratio of 4.3 for men and 19.3 for females for sustaining an ACL injury.  When the NW/EW ratios £1 for each gender were combined, the risk ratio of sustaining an ACL injury was 4.1. 

Guest: Stefan Freudiger, Dipl. Ing. ETH


Name of Presenter: Niklaus F. Friederich, MD


Skiing with "carving" skis: Different styles - different load patterns -
different injury patterns?
- A biomechanical analysis utilizing force plates fixed to the skis

Friederich Niklaus F*, Freudiger Stefan#, Doessegger Alain+, Kessler Urban+

* Head, Department of Orthopaedic Surgery/Traumatology
Kantonsspital Bruderholz
CH-4101 BRUDERHOLZ/Switzerland

# Ingenieurbüro Flugwesen und Biomechanik IFB AG, Bündackerstrasse 67,
CH-3047 Bremgarten/Switzerland

+ Universitätsinstitut für Sport, Universität Basel
St. Jakobshalle, CH-4000 Basel/Switzerland


Hypothesis
The "new" style in skiing utilizing more tailored skis ("Carving skis")
leads to greater loads at turning, thus increasing the risks of injuries to
knees and feet in skiers

Method
The tests were performed on a steep slalom slope, with no sun during the
whole day in order to keep snow conditions consistent. Average steepness
angle was 32.6°. A track with three turns with a radius of 10m each were
marked onto the snow. The turns were marked also with poles. Speed was
checked with a "Laser gun" (LTI 20.20, Laser Technology USA) as they are
used by law enforcement agencies. All turns were recorded with time-coded
video cameras. Load onto the skis were recorded with specially designed
force-plates (eight channels for each ski) which were attached to the skis
(Marker GmbH, Germany). The plates height was 20 mm. The skier had an
overall height of 50mm (which was 55mm less than they usually preferred on
their "normal" carving skis). All readings were continuously read at a
sample rate of 100 Hz and stored in a small computer, which was put in a
small backpack which was attached to the skier and which did only minimally
influence the skiers ability to make perfect carving turns. The skis
utilized were a so-called "Funcarver" (Funcarver F 20, Völkl, Germany;
technical radius 13.5m) and a "Racecarver" (Racevarver P 40 F1, Völkl,
Germany; technical radius 21.5m)
Two experienced skiers able to perform consistent "carving turns" tested
three different skiing styles (closed position, open position, race
position). There were a total of 60 runs. All data stored in the computer
were later analyzed utilizing a special program designed by M. Marohn
(Marker GmbH, Germany) and tabulated in Excel-spreadsheet format (Microsoft
Corp, Redmond, USA)

Results (Average of seven runs of two skiers each)

Time of turn [s] Radius[m] Speed[km/h]
Accel[m/s2] Ang [°]

Funcarver ³close² 2.87 9.88 38.9
11.8 50.3

Funcarver ³wide² 2.10 9.88 53.2
22.1 66.0

Racecarver 2.16 9.88 51.7
20.9 64.8


Legend Time of turn: Time to complete the turn (in seconds), Radius: Radius
of the measured turn (in meters), Speed: Speed as measured/calculated (in
km/h), Accel: Zentripetal acceleration (in m/s2), Ang: Angulation of the
ski/plate relative to the slope (in degrees)

Funcarver ³wide² Funcarver
³closed Racecarver

Load In/Out: 30%/70% 30%/70%
30%/70%
Load on skier: 2.5 - 3g 2.5 - 3g
2.5 ­3g
Pos. of max. load (from boot tip)
Begin of turn: 95mm anterior 77mm anterior 95mm
anterior
End of turn: 85mm posterior 70mm posterior 100mm
posterior
Flexion of inner knee ³hip below knee² minimal flexion flexion
depends on style


Conclusions
The ³wide² carving style which looks to give a more ³stable² position at the
beginning of the turn, may create critical load cases for the knee joint
(posterior load at the end of the turn together with a hip-below-knee
position) which may provoke injuries to the soft tissues of the knee
(menisci, anterior cruciate ligaments) and may therefore not be a
recommended skiing style.

Acknowledgment
The authors would like to thank ProMotio (Foundation for Biomechanical
Research, Basel) and the Marker-Company for generously supporting the study
with technical material. None of the authors have received or will receive
benefits for personal or professional use from a commercial party related
directly or indirectly to the subject of this article.

C. Fink

 

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The Effect of Mechanical Stress and Cytokines on Nitric Oxide Production in the Menisci

 

B. Fermor, J. B. Weinberg*, D. S. Pisetsky*, M. A. Misukonis*,

                                                  and F. Guilak

⁺University Hospital for Traumatology Innsbruck, Austria;
Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC; *Department of Medicine, VA and Duke Medical Centers, Durham, NC

 

 

Introduction.

Nitric oxide (NO) is a free radical, which is important in mechanical signal transduction, and may be involved in the degeneration of menisci and articular cartilage. The goal of this study was to determine if meniscal fibrochondrocytes respond to mechanical stress and to the presence of cytokines by increasing NO production in vitro.

 

Materials and Methods.

Medial and lateral porcine menisci were obtained within four hours of sacrifice. Ten cylindrical explants (5mm diameter and 2mm in thickness) were harvested from the femoral surface of each meniscus. The samples were incubated in culture medium for 72h and then dynamically compressed (0.5 Hz, 0.1 MPa), or stimulated with varying concentrations of cytokines (IL-1b, TNF-a). Nitric oxide production, NO synthase (NOS) antigen expression, and cell viability were measured.

 

Results.

Nitric oxide production by meniscal explants was significantly (p<0.01) increased by compression as well as by the presence of IL-1b and TNF-a compared to control samples. Compressed menisci expressed NOS2 antigen by immunoblot analysis, while uncompressed menisci did not. Significant (p<0.05) zonal differences were observed in basal and compression-induced NO production.

 

Conclusion.

Our findings provide direct evidence that dynamic mechanical stress and the presence of inflammatory mediators influence the biological activity of fibrochondrocytes. Since NO is known to affect collagen and proteoglycan synthesis, increased NO production might play a role in the development of degenerative tissue changes.

Supported in part by NIH grants AR39162, AR43876, and AG15768, the VA Research Service, and by Flexcell International, Inc. 

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David L. Helfet            , MD                                                                                                                           

·         The Hypothesis – What is the question?

The hypothesis of the study is that MR imaging, with concomitant MR angiography, is accurate in detecting soft tissue, osseous, cartilagenous, and neurovascular injury following multiple-ligament knee injury, including knee dislocation.

 

·         Method – How was the question investigated?

Retrospective search was performed with patients presenting with reported knee dislocation who underwent both MRI and surgical reconstruction.  Twenty-one patients met these criteria (mean age 32.6 years).  Preoperative MR diagnoses of soft tissue, osseous and neurologic injury were compared with operative findings. MR angiography of the popliteal vessels were performed in 17/21 patients.

 

·         Results – What were the results?

Data/Statistical analysis:   There was excellent correlation (kappa > 0.8) between MR and operative findings with regards to size and location of ligament, tendinous and meniscal tears.  There were 17 complete and 4 partial ACL tears; 12 complete and 9 partial PCL tears.  All ten nerve injuries seen prospectively on MR were confirmed at surgery; 4/10 nerve injuries resulted in symptoms, ranging from mild paresthesias to profound irreversible deficits.  Six patients had both conventional and MR angiography with 100% agreement between the studies.  In one patient, intimal flap seen prospectively on MRA was confirmed on conventional angiography.

 

        Conclusions

MR imaging is an accurate method in assessing damage to supporting structures of the knee following knee dislocation, and is helpful in planning appropriate surgical treatment.  Preoperative MR imaging may also identify abnormal nerve architecture, some of which results in clinically evident deficits.  MR angiography provides a noninvasive, rapid assessment of regional vessels, which may be done at the time of MR imaging, and may obviate the need for conventional contrast angiography following severe knee trauma.

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Tennessee Orthopaedic Alliance, Nashville, TN 37205

            Intra-substance tears of the anterior cruciate ligament, once considered rare in children and adolescents with open physes, are now being reported with increasing frequency.  When a child or adolescent presents with a torn anterior cruciate ligament, the physician is faced with a treatment dilemma.  The natural history of conservatively treated complete ACL tears is generally poor in skeletally immature patients.  Even so, many authors still advocate a conservative approach because of the risk of iatrogenic bone growth disturbance that may be caused by surgical intervention.  The purposes of this study are to describe an intra-articular ACL reconstruction technique that follows the generally accepted principles of ACL reconstruction in adults, but theoretically minimizes the risk of physeal injury by not transgressing either the tibial or femoral physis; and to determine the results of this technique using quadruple hamstring ACL reconstruction for children and adolescents who have open femoral and tibial physes. 

From 1993 to 1999, 12 patients (mean age 13; range 11 years, 1 month to 14 years, four months) had ACL reconstruction with quadruple hamstring tendons.  Eight of the twelve patients had a meniscal repair.  All patients returned for followup at a mean of 4.2 years (range 2 to 8.2 years).  The mean growth from the time of surgery to followup was 16.3 cm (range 7.5 to 38 cm).  The difference in lower limb length, measured on ortho roentgenograms, was not clinically significant.  The mean score on the IKDC subjective evaluation form was 96.5 (range 86 to 100).  KT 1000 ligament laxity testing revealed a mean side-to-side difference of 1.6 mm.  Eight patients rated normal and five rated nearly normal when evaluating according to the criteria of the objective 2001 IKDC knee examination form.  We conclude that this surgical technique can be performed in preadolescent patients with efficacy and relative safety.

                                    M.P. Arnold, Albert van Kampen, Leendert Blankevoort

·         What is the question?

In an earlier study (presented to the ACL-study group at the Rhodos-meeting 2000), tension in ACL-grafts during the operation was measured. Two different patterns of tension-curves, U- and L- shaped curves were found. The tension-curve of the normal ACL has been measured by other authors up to 90° of knee flexion. The goal of this study was to measure the tension in the normal ACL over the whole range of motion

·         Method – How was the question investigated?

In 6 intact fresh frozen cadaver knees the tibial ACL-insertion together with a tibial bone block was drilled out of the tibial head. This was done under arthroscopic as well as fluoroscopic control. In the centre of the resulting bone block a canulated cancellous screw was placed to which a custom-made tension measurement device was connected. The tensiometer was based on the tibial cortex at the level of the entry point of the tibial tunnel. The femurs were horizon­tally fixed to a table. The knees were manually moved, starting at 10° flexion with 10N ACL pretension, under rotational control through the whole range of motion. Additionally different angle / pretension- protocols were tested. Tension was measured with an electronic and a mechanical tensiometer

·         Results:

The tension-curves in the 6 knees showed a uniform pattern. At 4 important points of the curve the following tension was measured: in extension 32,7 N at an average (23-50 / SD 9,1), in hyperextension 72,3 N (30-115 / SD 28,8), at 90° flexion 11,7 N (3-22 / SD 7,1), at 135° flexion 21,8 N (15-26 / SD 2,7). The resulting curve showed a U-shaped pattern. Although the magnitudes of values for forces varied considerably between specimens, the patterns of loading with respect to the angle of flexion were remarkably consistent.

    ·        Conclusions:

At the tibial insertion of the normal ACL a U-shaped tension curve with high tension values in extension/hyperextension and rising beyond of 90° flexion was measured. It seems to be possible to imitate the tension pattern of the normal ACL by placing a b-pt-b – graft at the iso-anatomical insertion-sites.

G.  BELLIER M.D.

ARTHROSCOPIC MANAGEMENT OF KNEE OSTEOARTHRITIS

Material and methods : We were able to analyse 257 cases in 221 patients in a retrospective multicentric study run by the French Arthroscopic Society (S.F.A.).  Two scoring systems were used : Lequesne (French) and Womac (International).

Several arthroscopic techniques were performed : removal of loose bodies,meniscectomy,debridement,abrasion arthroplasty and microfractures.

The mean follow-up is 25,2 +/- 3 months.

Results : The Lequesne score is improved from 12,5 +/- 3,3 (pre-op) to 9,5 +/- 3,5 (maximum follow-up) with a statistically significant difference (p<0,0001).Reoperation was necessary in 50 knees (19,4%),mostly before 2 years (38 knees : 70%).

Only the primitive osteoarthritis and the chondrocalcinosis were improved (p<0,0001). The severity of the osteoarthritis is correlated with the clinical result : arthroscopy is more effective when there is still 50% of the thickness of the medial femoro-tibial space.Mechanical symptoms are correlated with a good result,but not patello-femoral joint pathology. A cartilage procedure such as abrasion arthroplasty is the most important predictive factor of a bad result (p<0,001) with  total meniscectomy (p<0,03).

Conclusion :  arthroscopic management (partial meniscectomy) of knee osteoarthritis is indicated only in primitive osteoarthritis with typical meniscal symptoms.

       T. Ait Si Selmi

             N. BONIN – T. AIT SI SELMI – H. DEJOUR † – Ph. NEYRET

·         The Hypothesis - What is the question?

Untreated ACL deficient knee in active individual will predispose them to instabilities, meniscal tears, and radiographic changes. ACL reconstruction itself may increase the onset of osteoarthritis.

The goal is to precise subjective, objective, functional, and radiological results of patients that underwent anterior cruciate ligament (ACL) reconstruction combined with a valgus tibial osteotomy.

·         Method – How was the question investigated?

From 1983 to 1999, we treated 66 knees by this combined procedure. We only studied the 47 ACL deficient knees that presented abnormal radiological findings in the medial tibiofemoral joint (remodelling changes (Grade B: 35%), prearthritic changes (Grade C: 65%)).We excluded 3 knees with evolved osteoarthritis (Grade D), 11 knees with asymmetrical opening of the lateral compartment and 5 knees with excessive constitutional genu varum without medial radiological compartmental changes.

35 (74.5%) of the 47 knees were retrospectively reviewed at 11 years mean follow-up (range, 1-16 years). A free bone-patellar tendon-bone graft was harvested to reconstruct the ACL. Often a Lemaire type extra articular procedure was performed (24 knees). The tibial osteotomy was a lateral closing wedge in 25 cases and a medial opening wedge in 10 cases.

IKDC score was used. Radiologically we checked axis, anterior tibial translation in monopodal stance and radiological findings in 34 of the 35 knees. Long leg films were available in 30 patients.

The mean age at operation was 32 years (18-49). Delay between injury and surgery averaged 8 years (range, 1-33 years). Sixty-six percent of the patients (N=23) had previously lost the medial meniscus at time of surgery.

·         Results – What were the results?

                -Data

         At review, 93 % of the patients were very satisfied or satisfied with their operated knee. Subjective score including knee function, symptoms and activity level average 78/100 (range, 46-96). 48% of the patients could regularly practice leisure sports like tennis or skiing.

               -Statistical analysis

The overall IKDC objective score was normal (A) for 5 knees (14%) and nearly normal (B) for 16 knees (46%). It was abnormal (C) for 12 knees (34%) and severely abnormal (D) for 2 knees (6%). The IKDC score was correlated with monopodal weight bearing translation pre and post operatively.

In medial compartment, radiological progression of osteoarthrosis was seen in 5 knees (15%) : 3 of 14 knees have evolved from grade B to C and 2 of 20 knees from grade C to D. Axial femoro-tibial correction was 6.8 degrees at follow up in group B and 4.7 degrees in group C.

In lateral compartment, remodelling changes occurred in 18 knees (53%) and pre osteoarthritic changes in 2 knees (6%) without correlation with axial correction.

·        Conclusions

Performing a valgus tibial osteotomy combined with an ACL reconstruction stabilizes the knee and stop the early progression of osteoarthitis. It has to be considered in chronic ACL deficient knees when radiological pre-arthritis is noticed particularly in case of previous medial meniscectomy or acquired malalignment.

Name of Member  Mitsuo Ochi

Name of Presenter: Mitsuo Ochi

TITLES: Tissue-engineering Technique for Repair of Cartilage Defect with ACL Deficiency

The Hypothesis – What is the question?

An acute tear of the anterior cruciate ligament (ACL) is often associated with injuries to the articular cartilage and subchondral bone.  These injuries may progress to full-thickness cartilage defects, causing disabling pain and locking and inducing osteoarthritic changes of the knee.  Although numerous attempts to repair the cartilage defect have been promoted, they fail to repair it with hyaline cartilage.  Recently, the clinical results of autologous chondrocyte implantation (ACI) have been successfully reported.  However, there are some problems in their methotology concerning about (1) maintenance of chondrocyte phenotype during monolayer culture, (2) risk of leakage of injected cells and (3) uneven distribution of implanted cells in the cartilage defect.  We have employed a new technology to create cartilage-like tissue by tissue engineering in order to overcome the problems and applied it clinically for the cartilage injury since 1996.

  Methods – How was the question investigated?

Experimental studies

(1)  Chondrocyte phenotype: In in vitro culture study using human and rabbit chondrocytes, morphological and biochemical examination have been performed to compare the properties between chondrocytes in atelocollagen gel (as scaffold in 3D culture) and those in suspension.

(2)  ＆(3) In in vivo study using rabbit knee joint, articular cartilage defect was treated with transplantation of cartilage-like tissue (cultured chondrocytes embedded in atelocollagen gel) or chondrocyte transplantation in suspension.  Histologic and biochemical and biomechanical properties between them were evaluated.

Clinical study

Ten patients (3 men and 7 women, aged from17 to 39 years) who suffered cartilage injury associated with ACL deficiency treated with this method were followed up at least two years.  MRI and arthroscopic examination were performed to evaluate the property of the reparative tissue.

  Results- What were the results?

Experimental studies

(1)  After 3 weeks culture, chondrocytes embedded in atelocollagen gel proliferated and synthesized extracelluar matrix maintaining their phenotype.  In contrast, chondrocytes in suspension proliferated by twice losing their round morphology.  Total amount of chondroitin sulfate and the ratio of chondroitin 6 sulfate to 4 sulfate was significantly higher in chondrocytes in atelocollagen gel than those in suspension culture (61.4 ± 19.7 vs. 3.3 ± 1.7 nmol/ cell x 10^-6, p<0.001, 2.35 ± 0.24 vs. 2.09 ± 0.28, p=0.02)

(2)  &(3) In the atelocollagen gel transplant group, the hyaline cartilage-like tissue repaired the cartilage defect and a steady integration of the grafted tissue to the adjacent normal cartilage was detected.   In addition, cells in the reparative tissue showed s-100 antigen and their matrices were stained with type II collagen antibody immunohistochemically.   Furthermore, almost all chondrocytes labeled with fluorescent DiI before transplantation were detected evenly in the grafted site in the atelocollagen gel transplant group, whereas no marked chondrocytes were observed in the group whose chondrocytes were cultured in the suspension cultivation method and were injected into the defect 1 month postoperatively.

Clinical study

At two years after ACL reconstruction and cartilage-like tissue transplantation, all patient had stable knee without pain or locking.  MRI and arthroscopic examination revealed that the transplant became smooth and hyaline like cartilage. 

Conclusion

These results in experimental and clinical studies indicated that transplanting chondrocytes embedded in atelocollagen gel promotes cartilage repair, which maintains their phenotype and prevents both leakage from the graft site and uneven distribution.  This method should be a promising technique to repair cartilage defect associated with ACL deficiency.

 Suvà D, Genoud P, Sati M, Fritschy D

Clinique et policlinique d’orthopédie et de chirurgie de l’appareil moteur, University Hospital of Geneva, Geneva  Switzerland.

·         The Hypothesis - What is the question?