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First published on October 11, 2005, doi:10.1177/0363546505278706
This version was published on January
1, 2006
The American Journal of Sports Medicine 34:98-107 (2006)
© 2006 American Orthopaedic Society for Sports Medicine
Human Meniscus Allografts’ In Vivo Size and Motion Characteristics
Magnetic Resonance Imaging Assessment Under Weightbearing Conditions
Marc Rankin, MD*,
Frank R. Noyes, MD
,
Sue D. Barber-Westin,
,
Stephen G. Hushek, PhD
and
Albert Seow, MD||
From the * Rankin Orthopaedics and Sports Medicine Center, Washington, District of Columbia, the Cincinnati Sportsmedicine Research and Education Foundation, Cincinnati, Ohio, Norton Hospital, Louisville, Kentucky, and the || Department of Radiology, University of Louisville, Louisville, Kentucky
Address correspondence to Sue D. Barber-Westin, c/o Cincinnati Sportsmedicine Research and Education Foundation, 10663 Montgomery Road, Cincinnati, OH 45242 (e-mail: sbwestin{at}csmref.org).
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ABSTRACT
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Background: Although many reports have described clinical outcome of meniscus transplants, their size and motion patterns are not well understood. This study assessed postoperative in vivo size and motion patterns of meniscus transplants under full weightbearing conditions.
Hypothesis: The human meniscus transplant has size and motion characteristics similar to the native menisci.
Study Design: Case series; Level of evidence, 4.
Methods: Eight meniscus transplants in 7 knees were studied 15 to 34 months postoperatively. The knees were scanned in an open magnetic resonance imaging 0.5-T superconducting magnet while standing. Single slice sagittal and coronal images were obtained at 0°, 30°, 60°, and 90° of flexion in the operative and contralateral knees.
Results: The mean height and width of the anterior and posterior horns of the transplants were similar to those of native menisci. The millimeters of coronal displacement of motion of the midbody were also similar between the transplants and the native menisci. The anterior horn of the native medial menisci moved a mean of 5 mm more (total anterior to posterior translation, P < .05) than did the transplants. The posterior horn of the native medial menisci, and both horns of the native lateral menisci, also tended to move more than the corresponding horns of the transplanted menisci, although this result could not be confirmed statistically, given the number of menisci studied.
Conclusion: Meniscus transplants had similar size and midbody motion characteristics as the native menisci. The horns of the meniscus transplants tended to show decreased motion compared with the native menisci. The operative techniques and subsequent healing of the graft bone and peripheral attachments provided a stable meniscus construct.
Key Words: meniscus • transplant • MRI • motion
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INTRODUCTION
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The risk for tibiofemoral arthrosis after meniscectomy has been demonstrated in clinical studies4,9–11,25,26,37 and is increased in knees with a deficient anterior cruciate ligament (ACL)12,15,20,21 and lower limb axial malalignment. The meniscus provides vital load-bearing and shock-absorbing functions important for the integrity of the articular cartilage.2,5,6 Transplantation of human menisci is designed to potentially restore some load-bearing meniscus function, and the clinical outcome has been reported by several investigators.18,23,24,29,30,32 However, we are not aware of a clinical study that measured the in vivo motion patterns and size characteristics of meniscus transplants under full weightbearing conditions using MRI. Vedi et al34 conducted such a study on the characteristics of normal menisci, in which the size and motion patterns were described under weightbearing and nonweightbearing conditions. An understanding of meniscal transplant in vivo motion and size characteristics has broad implications regarding surgical technique and potential chondroprotective effects postoperatively.
The purpose of this study was to compare the size and motion patterns of meniscus transplants using MRI under weightbearing conditions with those of the corresponding native menisci in the contralateral knee 1 to 3 years post-operatively.We hypothesized that meniscus transplants would demonstrate similar size and motion characteristics as native menisci in the contralateral knee in the same patient.
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MATERIALS AND METHODS
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Patients
Eight cryopreserved (Cryolife Inc, Kennesaw, Ga) meniscus transplants in 7 knees were evaluated a mean of 24 months (range, 15–34 months) postoperatively. The 7 patients were randomly selected from a cohort of 14 meniscus transplant recipients who met the inclusionary criteria: (1) had undergone surgery at least 1 year before MRI, (2) lived in close proximity to our center, (3) had no symptoms with daily activities and was able to stand for 1 hour without pain or swelling, and (4) had no contraindications to MRI. The study was approved by the Human Studies Committee of the University of Louisville Health Sciences Center.
A medial meniscus allograft had been implanted into 4 knees; a lateral meniscus allograft, into 2 knees; and a medial and lateral meniscus allograft, into 1 knee in the same patient 3 months apart. There were 6 men and 1 woman whose mean age at surgery was 31 years (range, 18–35 years). Anteroposterior and lateral radiographs were used to obtain approximate width and length measurements for the meniscus transplant in the method described by Pollard et al.22
A mean of 127 months had elapsed between the original knee injury and meniscus transplantation (Table 1
). A mean of 3.4 operative procedures had been done in the 7 knees before the meniscus allograft. Three knees had ACL reconstructions, which all had failed and required revision. One knee had a high tibial osteotomy (HTO) 15 months before the meniscus transplant, and 1 had an osteochondral autograft transfer (OAT) procedure 16 months before the meniscus transplant. A total of 15 partial or total meniscectomies had been done in the 7 knees.
MRI Testing Procedures
The knees were scanned in an open-configuration Signa SP Magnetic Resonance Imaging System (General Electric Medical Systems, Milwaukee, Wis). This system, previously described by others,14,34 is a 0.5-T superconducting magnet in which the windings are located in separate but communicating cryostats. The vertical orientation of the scanner allows the patient to stand between the cryostats with the knee at isocenter (Figure 1). Single slice sagittal and coronal images were obtained on both knees at 0°, 30°, 60°, and 90° of knee flexion (angles were measured with a goniometer). We created a support apparatus to assist the patients as they stood and held these degrees of knee flexion (Figure 2). Dynamic images, 5 mm thick, were acquired in near real time and were prescribed relative to the tibial plateau by positioning a 3-dimensional mouse (Flashpoint, IGT, Boulder, Colo) attached to a shin guard via a goose-neck apparatus.34 The 3-dimensional mouse position was communicated automatically to the scanner, and its attachment to the shin guard allowed for reproducible slice positions. The imaging sequence was a spoiled gradient echo, echo time (TE) = 5.7 milliseconds, repetition time (TR) = 19.9 milliseconds, flip angle = 60°, field of view (FOV) = 24 x 24 cm, receiver bandwith (RBW) = 6.94 kHz, and 256 x 128 matrix, that acquired an image every 3 seconds.
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Figure 1. An open-configuration 0.5-T superconducting magnet. The vertical orientation of the scanner allowed the patients to stand, and images were taken under full weight-bearing conditions.
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Figure 2. A support apparatus provided increased comfort as the patient stood and held different degrees of knee flexion.
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The height, width, motion, and displacement of the meniscus transplants and of the corresponding native menisci in the contralateral knee were determined as described by Vedi et al.34 In the sagittal plane, motion of the anterior and posterior horns and the midbody of the menisci were determined by measuring the perpendicular distance from the outer inferior edge of the meniscus to the outermost edge of the articular cartilage of the tibial plateau at 0°, 30°, 60°, and 90° of flexion. The height of the outer meniscus edge and width of the horns were measured at each knee flexion angle (Figure 3). In the coronal plane, meniscal displacement was determined at each flexion angle by measuring the distance from the outer inferior edge of the meniscus to the outermost edge of the tibial plateau. The width of the anterior and posterior horns was also measured at each knee flexion angle in the coronal plane.
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Figure 3. Illustrations of the computer-assisted measurements made of the native and transplanted menisci height and width from the coronal (A) and sagittal (B) T1-weighted magnetic resonance images.
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In addition, meniscal displacement and signal intensity were assessed with coronal and sagittal supine, non-weightbearing, T1-weighted, fast spin echo (FSE) T2-weighted fat-saturated, and fast spin echo (FSE) proton density images. T1-weighted: TR = 650 milliseconds; TE = 21 milliseconds; FOV = 18 x 18 cm; 4 mm thick; 256 x 128; RBW = 10.4; NEX = 1; acquisition time = 3 min 26 seconds. Proton density: TR = 3000 milliseconds; TE = 29 milliseconds; FOV 18 x 18 cm; 4 mm thick; 1-mm gap; 256 x 192; RBW = 10.4 KHz; NEX = 1; acquisition time = 5 min. T2-weighted FSE with fat saturation: TR = 5000 milliseconds; TE = 88 milliseconds; FOV 18 x 18 cm; 4 mm thick; 1-mm gap; 256 x 128; RBW = 10.4 KHz; NEX = 1; acquisition time = 3 min. Intrameniscal signal was graded according to the method described by Stoller et al.28 Grade 1 represented a nonarticular focal or globular intrasubstance focus of increased signal; grade 2 represented a linear focus of intrasubstance increased signal that extended from the capsular periphery of the meniscus but did not involve an articular meniscal surface; and grade 3 represented an area of increased signal intensity that communicated or extended to at least 1 articular surface.
Subjective and Functional Assessment
Before surgery and at the most recent clinical follow-up examination, patients completed the validated Cincinnati Knee Rating System as a part of a larger prospective study on meniscus transplantation18 to determine symptoms, functional limitations, and activity levels.1 The pain scale of the Cincinnati Knee Rating System determined the highest activity level possible without the patient experiencing pain. On this scale, a score of 0 identified pain with daily activities; 2, moderate pain with daily activities; 4, no pain with daily activities but pain with light sports (bicycling, swimming); 6, no pain with light sports but pain with moderate sports (running, twisting, turning); 8, no pain with moderate sports but pain with strenuous sports (jumping, hard pivoting); and 10, no pain with strenuous sports. The rating system included a patient grade of the overall condition of the knee on a numeric 10-point scale. Four descriptive terms provided on the scale were poor (under number 2), fair (under number 4), good (under number 6), and normal (under number 10).
Operative Technique
The techniques for medial and lateral meniscus transplantation have been previously described in detail.18,19 Anteroposterior and lateral radiographs were used to obtain approximate width and length measurements for the meniscus transplants.22 The meniscus bed was prepared by removing any residual meniscus tissue (leaving a 2–3 mm meniscus rim) and rasping the adjacent synovium. Medial meniscus transplants had a posterior bone plug 8 mm in diameter and 12 mm in length and an anterior bone plug 12 mm in diameter and 12 mm in length. A tibial tunnel was drilled at the anatomical insertion of the posterior horn attachment just medial and proximal to the posterior cruciate ligament attachment. The knee was flexed to 20° under a maximum valgus load, and the posterior horn bone attachment was passed into the tibial tunnel. A 4-mm bone tunnel was created at the base of the anterior horn attachment site, which exited at the anterior tibia, and the anterior horn was seated. Full knee flexion and extension were performed to determine proper graft placement and fit. A meniscus repair was performed in an inside-out fashion, starting with the posterior horn, using multiple vertical divergent sutures both superiorly and inferiorly.16,27 Constant tension was placed on the meniscus from posterior to anterior to restore circumferential tension.
Lateral meniscus transplants contained a rectangular portion of bone from the tibial plateau, which incorporated the anterior and posterior attachments, and measured 8 to 9 mm. The length of the bone attachment was usually 35 mm, but it could be altered if required. A rectangular bone trough was prepared at the anterior and posterior tibia attachment sites to match the dimensions of the prepared lateral meniscus transplant. A 4-mm anterior tibial tunnel was drilled into the bone trough anteriorly 2 to 3 cm distal to the joint line. The transplant was inserted into the trough, and the bone portion of the graft was seated against the posterior bone buttress to achieve correct placement of the attachment sites. The knee was flexed, extended, and rotated to confirm correct transplant placement. The central bone attachment sutures were tied, and inside-out meniscus repair was performed.
Postoperative Rehabilitation
A long leg postoperative brace (Smith & Nephew Don Joy Inc, Carlsbad, Calif) was worn for 6 weeks. Immediate knee motion from 0° to 90° was allowed, with flexion increased to 120° at 3 to 4 weeks and 135° at 5 to 6 weeks. Toe-touch weightbearing activity was allowed for the first 2 weeks and then slowly progressed to 50% body weight at 4 weeks and full body weight at 6 weeks. Flexibility and quadriceps strengthening exercises were begun immediately after surgery. Balance, proprioception, and closed kinetic chain exercises were implemented when the patient achieved full weightbearing activity. Stationary bicycling with low resistance was begun at 7 to 8 weeks, and swimming and walking programs were initiated at 9 to 12 weeks. Return to light recreational sports was delayed for at least 12 months. Patients were advised not to return to high-impact activities or strenuous athletics because of concurrent articular cartilage damage.
Statistical Analyses
Post hoc power analysis determined that with the sample size set to 8, there was 95% power to detect a 3-mm difference between the meniscus transplants and the native menisci in terms of height, width, and motion (significance level of .05). Paired Student t tests were conducted to determine if significant differences were present for these variables for each knee flexion angle.
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RESULTS
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Patient Subjective and Functional Outcome
The preoperative and most recent follow-up patient subjective and functional data are shown in Table 2. Significant improvements were noted for the scores in pain, patient perception, squatting, and running (P < .05). Preoperative moderate pain was experienced with daily activities in 5 patients, and this pain was relieved in all at follow-up. No patients had tibiofemoral compartment pain at follow-up. Before the operation, 5 of the 7 patients had given up sports activities, and 2 were participating with noteworthy pain and functional limitations. At the most recent follow-up (mean, 40 months postoperative), 6 patients had returned to low-impact activities, avoiding running, twisting, and turning, based on our advice to preserve the joint for as long as possible. One patient returned to strenuous sports involving running and twisting and was asymptomatic. One patient did not return to athletics because of the knee condition.
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TABLE 2 Subject Clinical Data on Pain, Swelling, Patient Grade, and Sports Activity Levels Before and After Meniscus Transplantationa
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Meniscus Height (Sagittal Plane)
The posterior horn of the meniscus transplants maintained a consistent height throughout the range of knee motion (0° to 90°) (Table 3), which was similar to the mean height of the posterior horn of the native menisci. The individual height and width measurements obtained for the posterior and anterior horns are shown in Table 4.
The height of the anterior horn of the meniscus transplants was similar to that of the native menisci throughout the range of knee motion. The transplants demonstrated a minimum mean height of 7 ± 1 mm and a maximum mean height of 8 ± 1 mm, which did not correlate with knee flexion. The mean height of the native menisci had a relationship with knee flexion, as the mean height of the anterior horn increased from 6 ± 1 mm at 0° of flexion to 8 ± 2 mm at 90° of flexion (Table 3
).
Meniscus Width (Sagittal Plane)
The mean width of the posterior horn was similar between the meniscus transplants and the native menisci throughout the range of knee motion, 14 ± 3 mm and 15 ± 1 mm, respectively (Table 3).
The mean width of the anterior horn was similar between the meniscus transplants and native menisci throughout the range of knee motion, 14 ± 4 mm and 14 ± 2 mm, respectively. The transplants demonstrated an increase of only 0.6 mm in the variation of the anterior horn height compared with the native tissue.
Meniscus Width (Coronal Plane)
The mean width in the coronal plane was similar between the meniscus transplants and the native menisci throughout the range of knee motion (Table 5). In Table 5, the allograft mean ± SD at 30° of flexion is 15 ± 2, and the native menisci is 13 ± 2.
Meniscus Motion (Sagittal Plane)
The total motion of the anterior horn, posterior horn, and midbody for the medial meniscus transplants and native medial menisci from 0° to 90° of flexion are shown in Table 6. In 1 transplant, midbody measurements could not be made; in 1 native meniscus, anterior horn measurements could not be made because of artifacts from other operative procedures. The anterior horn of the native medial menisci moved a mean of 5 mm more (total anterior to posterior translation) than the transplants (P < .05), and the posterior horn moved a mean of 3 mm more than the transplants (Figure 4). The apparent difference in motion of the posterior horns was not statistically significant, given the size of the sample available. Cases 2 and 4 showed an absence of motion in the posterior horn, but the midbody data showed little medial-lateral motion.
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Figure 4. Illustrations in the axial plane of the native and transplanted menisci, approximating the pattern of meniscal displacement from full extension to 90° of flexion (slashed lines). These illustrations are not to scale.
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The total translation of the anterior horn, posterior horn, and midbody for the lateral meniscus transplants and native menisci from 0° to 90° of flexion are shown in Table 7. The anterior and posterior horns of the native lateral menisci moved a mean of 3 mm more than the allografts. The apparent difference in motion of the anterior and posterior horns was not statistically significant, given the size of the sample available. The motion of the midbody was similar between the native lateral menisci and the transplants from 0° to 90° of flexion.
Meniscus Displacement (Coronal and Sagittal Planes)
The millimeters of radial meniscus displacement measured in the coronal plane were similar between the meniscus transplants and native menisci at all knee flexion angles (Table 8). In the sagittal plane, the mean displacement of the posterior horn of the transplants was 2.2 ± 3.1 mm (range, 0–9 mm). Four transplants had no displacement, 3 had minor displacement (3 mm), and 1 had major displacement (9 mm). The mean displacement of the anterior horn of the transplants was 1.9 ± 2.5 mm (range, 0–6 mm). Four transplants had no displacement, 2 had minor displacement, and 2 had major displacement (5–6 mm).
Signal Intensity
Signal intensity was rated as grade 1 in 2 cases, grade 2 in 4 cases, and grade 3 in 2 cases.
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DISCUSSION
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This study is the first to report on the in vivo motion and size characteristics of human meniscal transplants under full weightbearing conditions. A similar study regarding the characteristics in normal menisci was conducted by Vedi et al,34 and we followed the protocol of those investigators to measure meniscal size and motion.
The data from our investigation demonstrated that the height and width of the transplants were consistent from 0° to 90° of knee flexion in both the sagittal and coronal planes. The size characteristics of the transplants were similar to those of the contralateral native menisci. The results confirmed that the operative techniques and rehabilitation program allowed for the survival of implanted meniscus transplants at least up to 3 years postoperatively. Although the small number of cases in our study precludes definitive conclusions, we demonstrated that our measurement technique could be successfully conducted and in vivo motion patterns measured on an open vertically oriented MRI magnet. Other investigators have used this same technique to measure tibiofemoral kinematics in normal,7,8,13,34 ACL-deficient,13,14 and ACL-reconstructed knees.13
Vedi et al34 used an open vertically oriented MRI to measure the motion of native menisci in 16 male football players aged 15 to 18 years. Meniscal motion was documented in the sagittal and coronal planes from 0° to 90° of flexion under full weightbearing and nonweightbearing conditions. Significant differences were found between the loaded and unloaded scans in the motion of the anterior horn of the lateral menisci (mean motion, 9.5 mm and 6.3 mm, respectively; P < .05) and in the height of the anterior horn (4.0 mm and 2.7 mm, respectively; P < .05). The lateral menisci showed greater anterior-to-posterior translation than did the medial menisci, and the anterior horns had greater translation than did the posterior horns. The results of the native menisci in our study (under full weightbearing conditions) agreed in terms of greater translation of the lateral menisci compared to the medial menisci. However, we found little difference in translation between the anterior and posterior horns (mean difference, 2 mm). We used the nonweightbearing MRI protocol to assess meniscal displacement and signal intensity and, therefore, did not compare the height and width of the transplants between full weightbearing and nonweight-bearing conditions.
Investigators, using MRI open vertically oriented magnet techniques, have reported that there is little motion or rollback of the medial femoral condyle during progressive squatting from 0° to 120° of knee flexion.7,8 Authors have postulated that this result is because of both the shape of the medial tibia and the tight binding of the medial meniscus by its soft tissue attachments. The lateral femoral condyle rolls posteriorly with knee flexion, and the lateral meniscus subsequently moves more than the medial meniscus. Both medial and lateral menisci have little medial-to-lateral translation and radial displacement, conditions necessary to maintain the surface area of the tibiofemoral articulation under load or with knee flexion.
The use of MRI in the assessment of meniscus allografts postoperatively has been reported by others to be problematic. For instance, van Arkel et al33 reported that poor MRI technique resulted in a lack of a correlation between MRI data and clinical findings or follow-up arthroscopy observations. A relatively low field strength MRI system and an intraslice gap of 1.5 mm were thought to be responsible for the findings. The authors suggested use of a spin echo proton density or turbo spin echo technique, along with a 1.5-T scanner, to assess meniscus transplants and articular cartilage in a more reliable manner. Potter et al23 had a more favorable opinion of the usefulness of MRI in determining meniscus transplant characteristics. These authors used 2 FSE MR sequences in a 1.5-T superconducting magnet, 3- to 4-mm-thick sections with no intersection gap. Strong correlations were found between MRI and second-look arthroscopy observations and between articular cartilage deterioration and meniscus transplant failure. The posterior horn was a common area of failure, and the authors believed that the material properties of the meniscus transplant could have been inadequate for the loads placed on the tissue postoperatively. Our MRI protocol allowed for the assessment of meniscal characteristics between the transplants and the native menisci. The tendency toward limited motion observed in the posterior and anterior horns of the meniscus transplants may have been because of the inability of the surgical fixation technique to restore normal peripheral attachments, resulting in overconstraint of anterior-posterior translation. The long-term effect of this reduction in motion on transplant function and survivability remains to be determined. Of importance is that all of the transplants showed little mid-body mediolateral motion or displacement and thus appeared to remain in the normal tibiofemoral joint position. This positioning is a requirement for transplants to be able to function in a manner similar to native menisci.
Noyes et al18 reported on 24 meniscus transplants analyzed with MRI in a 0.7-T superconducting magnet at a mean of 35 months after implantation. Partial weightbearing conditions were simulated with a pulley-weight apparatus. In the sagittal plane, all but 1 transplant had little to no displacement. However, intrameniscal signal intensity was rated as normal in 1 transplant, as grade 1 in 13 transplants, as grade 2 in 11 transplants, and as grade 3 in 3 transplants and could not be evaluated in 1 transplant. On the basis of the results of our current and prior investigations, we believe that over time meniscus transplants undergo a deleterious remodeling process at different periods postoperatively, resulting in altered mechanical properties and leading to the potential for tearing, fragmentation, and degeneration under loading conditions.
The functional capabilities of meniscus allografts in the human knee remain unknown, and the potential chondroprotective effects have yet to be proven. There are multiple factors required for transplants to function in a similar manner as native menisci. Meniscus transplants must retain normal size and motion patterns, remodel to develop circumferential tensile stress (hoop stress), and have similar mechanical and material properties as native menisci to enable appropriate distribution of loads over a large section of the articular cartilage. Although our study demonstrated that the transplants in the short term retained size and midbody motion patterns similar to native menisci, all showed alterations in signal intensity. Other investigators have reported that meniscus transplants were smaller in size on MRI and had alterations in signal intensity.18,23,30 Ingrowth of cells into the transplant, removal of portions of the dense well-formed collagen framework, and replacement with more randomized and disorganized collagen tissues can cause increased signal intensity with a nonuniform patchy gray appearance.18 It is at this stage of the remodeling process that alterations in mechanical properties and decreased load-sharing capabilities may be expected.23 We believe that this is the case with most meniscus transplants and caution that their long-term survival is unpredictable.
The short-term and midterm results of meniscus transplants have been reported by many authors.23,24,30,33,36 Noyes et al19 recently described the clinical results of 40 meniscus transplants that were followed a mean of 40 months postoperatively. Of the patients, 89% rated the knee condition improved by the operation. Although all had noteworthy tibiofemoral compartment pain preoperatively, 68% had no pain and 33% had only mild pain at follow-up. Although the short-term results were encouraging in terms of reducing symptoms and increasing function, the long-term chondroprotective effects remain unknown.
Verdonk et al35 recently reported survival analysis of 100 viable meniscus transplants. The mean cumulative survival time was similar for medial and lateral transplants (11.6 years). The cumulative survival rates for the medial and lateral transplants at 10 years were 74.2% and 69.8%, respectively. When a medial meniscus transplant was combined with HTO, the survival rate increased to 83.3% at 10 years. Many authors have reported that meniscus transplants have an increased failure rate when implanted in varus-angulated knees, and this condition is now viewed as an absolute contraindication to medial meniscus translantation.3,17,31,32,35 In our study, 1 knee required an HTO, which was performed 15 months before the medial meniscus transplant. We prefer to stage these procedures, performing the osteotomy first to ensure adequate axial alignment is achieved and maintained before proceeding with the meniscus transplant, to decrease the risks for complications.
In our investigation, 3 patients required an ACL reconstruction, which was performed as a staged procedure to lessen the risks for complications. Other authors have noted an increased rate of meniscus transplant failure if performed in an ACL-deficient knee.31,32 All 3 of these patients had undergone prior ACL procedures elsewhere that had failed. We believe the restoration of normal axial alignment and knee motion limits is paramount in the consideration of meniscus transplantation candidates.17
The limitations of this study include the confines inherent with MRI, a small sample size, and short-term follow-up. The strengths of this study include the ability to use the contralateral native menisci within each subject under full weightbearing conditions to compare the MRI measurements of the meniscus transplants.
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CONCLUSION
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Meniscus transplants had similar size and midbody motion values as native menisci. The horns of the meniscus transplants tended to show decreased motion compared with the native menisci. Further study is required to determine if this decreased motion may have a negative impact on transplant survivability. The operative techniques and subsequent healing of the graft bone and peripheral attachments provided a stable meniscus construct. Future long-term studies are required to determine meniscus transplant chondroprotective effects.
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ACKNOWLEDGMENTS
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This research was funded by the Cincinnati Sportsmedicine Research and Education Foundation and the Noyes Knee Center. We acknowledge Norton Hospital, Louisville, Kentucky, for its assistance in testing and data reduction.
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FOOTNOTES
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Presented at the interim meeting of the AOSSM, New Orleans, Louisiana, February 2003.
No potential conflict of interest declared.
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ABSTRACT
INTRODUCTION
