The Journal of Bone and Joint Surgery 79:997-1006 (1997)
© 1997 The Journal of Bone and Joint Surgery, Inc.
Characterization of the Repair Tissue after Removal of the Central One-Third of the Patellar Ligament. An Experimental Study in a Goat Model*
CHRISTOPHER S. PROCTOR, M.D. ,
DOUGLAS W. JACKSON, M.D. and
TIMOTHY M. SIMON, M.S., LONG BEACH, CALIFORNIA
Investigation performed at the Orthopaedic Research Institute at the Southern California Center for Sports Medicine and Long Beach Memorial Medical Center, Long Beach
 |
Abstract
|
|---|
The purpose of this study was to characterize the repair tissue that develops after removal of a portion of the patellar ligament for use as a graft. A six-millimeter-wide strip was obtained from the central portion of the patellar ligament with tibial and patellar bone plugs from one knee (stifle joint) of eight goats. The repair tissue that formed in the defect was characterized in terms of its structural, material, histological, and ultrastructural properties twenty-one months after the operation. The contralateral patellar ligament served as a control. Representative specimens were taken from the proximal, middle, and distal portions of the repair tissue and the control tissue for histological study and examination with transmission electron microscopy.
The six-millimeter-long defect filled with repair tissue that increased the cross-sectional area by a mean of 42 per cent compared with the control values (p < 0.05). The maximum force to failure and the ultimate stress of the repair tissue were significantly decreased (by a mean of 51 and 65 per cent, respectively) compared with those of the controls (p < 0.001 for both). The stiffness also was reduced, by a mean of 27 per cent, but this was not significant (p > 0.05). Magnetic resonance imaging of the donor site showed slightly increased signal intensity compared with the intensity on the control side. Histological sections from the donor site contained collagenous (scar) tissue that was less organized, more cellular, and more vascular than the control tissue. Evaluation of the ultrastructure revealed that the repair tissue was composed primarily of collagen fibrils with a small diameter (range, fifty to 100 nanometers).
CLINICAL RELEVANCE: The results of the present study suggest that the repair tissue that develops after removal of a strip of the patellar ligament for use as a graft is not comparable with normal tissue in terms of its structural, material, histological, and ultrastructural properties by twenty-one months. This should be kept in mind when this repair tissue is considered for use as a graft for revision of a reconstruction of the anterior cruciate ligament.
|
Introduction
|
|---|
Use of the central one-third of the patellar ligament to reconstruct the anterior cruciate ligament apparently was first described by Jones in 1963. Since that time, many such reconstructions have been performed, and a small percentage have been complicated by problems related to the procurement of the patellar ligament graft4,8,10,11,17,19,21-23. Revision of a reconstructed anterior cruciate ligament is now performed frequently, and some authors have advocated reuse of the central one-third of the original donor patellar ligament for these procedures16.
We previously studied the entire patellar ligament, with use of a goat model, six weeks and six months after removal of the central 40 per cent of its width and found that the cross-sectional area of the donor ligament was significantly increased (p < 0.001 at six weeks and p < 0.01 at six months)12. However, there was a mean 50 per cent reduction in maximum force to failure of the patellar ligament at six months. Electron microscopy demonstrated an increased number of collagen fibrils with a small diameter (range, fifty to 100 nanometers) in the central portion of the donor site.
Other investigators have also examined the biomechanical and histological properties of the patellar ligament after removal of a section for a graft. Cabaud et al., in a biomechanical study of a canine model, found a slight decrease in maximum load to failure at four months and a slight increase in maximum load to failure at six months, compared with the values for contralateral, control ligaments. They also reported that the histological characteristics of repair tissue returned to normal. Other investigators, using canine5,18, rabbit3, and goat models12, have been unable to confirm the findings of Cabaud et al. Those subsequent studies consistently demonstrated that the cross-sectional area of the patellar ligament increased, the maximum force to failure and the stiffness decreased, and the segment removed from the ligament was replaced with disorganized scar tissue.
Magnetic resonance imaging has also been used to evaluate the donor site after removal of the central one-third of the patellar ligament from humans. Coupens et al., with use of the contralateral knee as a control, found that the cross-sectional area of the donor site was a mean of 53 per cent larger and that the signal intensity, which was initially high, returned to normal throughout the ligament by eighteen months. In a similar study, Nixon et al. found that the signal intensity of the repair tissue essentially returned to normal by two years postoperatively.
The purpose of the present study was to investigate the longer-term remodeling of the repair tissue at the donor site with respect to its gross appearance, its appearance on magnetic resonance images, the histological findings, the size and distribution of the collagen fibrils, and its biomechanical properties. To our knowledge, no previous investigator has specifically tested the biomechanical properties of the repair tissue in the reconstituted portion of the patellar ligament after removal of the central six millimeters. This is clinically important because some surgeons have proposed use of the repair tissue at the donor site for revision of reconstructions of the anterior cruciate ligament.
|
Materials and Methods
|
|---|
Experimental Animals
Eight female, skeletally mature Spanish goats that were four to five years old and weighed more than twenty-five kilograms were used.
Operative Procedure
All operative procedures were performed with sterile techniques with the animal under general anesthesia induced with xylazine hydrochloride and ketamine hydrochloride, as described previously12. Immediately before the operation, the animals received 2.4 million units of penicillin G benzathine suspension. An anterolateral approach was used to expose the stifle joint. The length and width of the patellar ligament of one knee from each animal were measured, and the middle six millimeters was split sharply in line with its fibers. Patellar and tibial bone blocks (six millimeters wide by fifteen millimeters long by five millimeters deep) were created with an oscillating saw, and the entire graft was removed. The defect in the ligament was loosely approximated with use of three stitches with number-0 Vicryl non-absorbable suture (Ethicon, Somerville, New Jersey) placed at the proximal, middle, and distal portions of the donor site. The animals were not immobilized postoperatively and were allowed unrestricted weight-bearing.
Evaluation Interval
All of the animals were killed by exsanguination, while under anesthesia1, at twenty-one months postoperatively. The lower limbs were removed at the hip and were amputated seven inches (17.8 centimeters) distal to the stifle joint. The specimens for biomechanical testing were immediately wrapped in a moist towel, placed in a plastic bag, and stored frozen at -40 degrees Celsius until testing. The specimens that were to be used for magnetic resonance imaging, histological study, and transmission electron microscopy were processed immediately.
Biomechanical Testing
The structural and material properties of the repair tissue and the control tissue were evaluated for six of the animals. All soft tissue was removed from the stifle joint, leaving only the patella, the patellar ligament, and the tibial plateau. The width of each patellar ligament was measured at its mid-point. The patellar ligament was split longitudinally to isolate the central six millimeters, determined according to markers placed during the operation or with use of direct measurement and a double-bladed scalpel set for six millimeters. The medial and lateral portions of the ligament were removed. The cross-sectional area of the central portion and that of the corresponding central six millimeters of the contralateral, control ligament were measured with an area-displacement digital micrometer. The tissue to be measured was placed in the slot portion of the device, and the blade was engaged in the slot until it was just touching the tissue. The blade was advanced slowly until the micrometer advance drive stopped, and a reading was recorded. All measurements were done twice. Measurements were made at the proximal portion of the patellar ligament (as close to the patellar insertion as possible), the middle portion, and the distal portion (as close to the tibial insertion as possible), and the average value for all three areas was recorded.
The patella and the tibial plateau were mounted in custom grips with the ligament aligned with a load cell (model 3169; Lebow, Troy, Michigan) and the direction of elongation. Tests to failure were conducted at a strain rate of 1000 millimeters per minute on an electromechanical Instron testing machine (model 4505; Instron, Canton, Massachusetts). The mechanism of failure was ascertained by direct visualization and by palpation of the torn ends of the graft. Osseous avulsions were determined by visual inspection and by palpation of the free ends of the ruptured ligament. The maximum force to failure, the stiffness, and the mode of failure were determined for each specimen. Stiffness was calculated from the slope of the linear portion of the force-displacement curve obtained from testing to failure.
Evaluation with Magnetic Resonance Imaging
The donor and control stifle joints from two animals were evaluated with magnetic resonance imaging, histological study, and transmission electron microscopy at twenty-one months. Immediately after death, the lower limbs and the muscles three inches (7.6 centimeters) proximal and distal to the joint line were removed. The knees were extended and placed in a plastic bag, which was sealed with tape. The knees were then placed in a high-resolution surface imaging coil (CP-FLEX coil; Siemens, Eastland, New Jersey), and magnetic resonance images were made with a high-resolution 1.5-tesla Magnetom Vision unit (Siemens). The standard examination consisted of contiguous three-millimeter images in the coronal and sagittal planes. A three-dimensional turbo spin-echo sequence with a repetition time of 2322 milliseconds and an effective time to echo of 132 milliseconds was used. The field of view had a resultant pixel size of 0.39 millimeter.
Histological Study and Evaluation with Transmission Electron Microscopy
After magnetic resonance imaging, section samples that were 1.5 to two millimeters thick were collected from the proximal, middle, and distal portions of the donor site for evaluation with transmission electron microscopy (Fig. 1). Each sample then was cut into three one-by-one-millimeter fragments that were identified as the interior (toward the intra-articular space), the central region, and the exterior (the outermost portion) of the donor site. The specimens were fixed in 2 per cent glutaraldehyde in sodium cacodylate buffer for at least twenty-four hours and then fixed in 1 per cent osmium tetroxide for one hour, followed by dehydration in graded ethanol. The specimens were embedded in resin, cured, trimmed, and cut into ultra-thin sections. The sections were stained with uranyl acetate and lead citrate and were examined with a Zeiss transmission electron microscope (Carl Zeiss, Thornwood, New York).
View larger version (30K):
[in this window]
[in a new window]
|
Fig. 1 Illustrations of the relative positions from which the specimens were taken for transmission electron miscroscopy (TEM) and histological study.
|
|
The diameters of the collagen fibrils within the specimens were determined from photographs of representative sections with use of image analysis. The diameters of the fibrils were sorted and grouped according to their specific size-ranges, and the percentage of the total area occupied by each group of fibrils was calculated.
Specimens for histological study were prepared from the remaining tissues (the ones that had not been studied with transmission electron microscopy). The specimens were taken from five locations: the site from which the patellar bone block had been removed; the proximal, middle, and distal portions of the patellar ligament; and the site from which the tibial block had been removed (Fig. 1). The specimens were fixed in neutral buffered 10 per cent formalin for one week and then were prepared for paraffin-embedding and sectioning. Osseous specimens were decalcified before they were embedded in paraffin. The specimens were oriented to cut cross sections. The cut sections were stained with hematoxylin and eosin and were examined with bright-field and polarized light microscopy.
The cross-sectional area of the whole patellar ligament also was determined from the slides of the cut histological sections and from the magnetic resonance images. The image of each tissue section or magnetic resonance image slice was captured digitally and analyzed for the cross-sectional area of only the patellar ligament tissue with image analysis (Olympus Cue-2; Olympus, La Palma, California). The per cent change was calculated as the (experimental value/[the control value - 1]) x 100.
Statistical Analysis
The results of biomechanical testing of the repair tissue were compared with those of the tests of the contralateral, control specimens and were analyzed with group t statistics. The non-parametric Mann-Whitney U test was used to compare the two groups with regard to the cross-sectional areas determined histologically and with magnetic resonance imaging. The distributions of the collagen fibrils were analyzed with one-way analysis of variance and the Tukey post test. An alpha of less than 0.05 was considered significant for all evaluations.
|
Results
|
|---|
Biomechanical Testing
Measurement of the six intact reconstituted patellar ligaments—that is, before excision of the central six millimeters for biomechanical testing—showed that the ligaments had increased in width by a mean of 53 per cent (p < 0.001) (Table I) compared with the control ligaments.
The maximum force to failure was significantly reduced (p < 0.001), by a mean of 51 per cent, in the repair tissue compared with the control value (Table I). The stiffness of the repair tissue was not found to be significantly decreased (p > 0.05), with the numbers available. The ultimate stress to failure was significantly reduced (p < 0.001), by a mean of 65 per cent, compared with the control value. All of the specimens failed at the mid-substance during biomechanical testing.
There was a mean 42 per cent increase in the cross-sectional area of the repair tissue compared with the control value; this difference was significant (p < 0.05). The cross-sectional area of the whole patellar ligament in the donor limb also increased significantly, by a mean of 269 per cent (p < 0.001) and 302 per cent (p < 0.05) as determined histologically and on magnetic resonance images, respectively (Table II).
View this table:
[in this window]
[in a new window]
|
TABLE II
CROSS-SECTIONAL AREA OF THE WHOLE PATELLAR LIGAMENT FROM THE DONOR SITE COMPARED WITH THAT OF THE CONTROL LIGAMENT AT TWENTY-ONE MONTHS
|
|
Evaluation with Magnetic Resonance Imaging
Magnetic resonance images of the donor site demonstrated a uniformly dark signal except for a small area of increased signal (Fig. 2). A normal patellar ligament typically demonstrates a uniformly dark signal. The sites of the bone plugs were still clearly evident as depressions. These observations suggest that the tissue signal within the donor site returns to nearly normal by twenty-one months after removal of the tissue for the graft. The anterior-posterior thickness of the donor site was a mean of 198 per cent greater than the control value (Figs. 3-A and 3-B). The cross-sectional area was also significantly increased (p < 0.05) (Figs. 4-A and 4-B and Table II).
View larger version (126K):
[in this window]
[in a new window]
|
Fig. 2 Magnetic resonance image showing the uniformly dark signal of the patellar ligament donor site and a small area increased signal (arrow) within the repair tissue.
|
|
View larger version (137K):
[in this window]
[in a new window]
|
Fig. 3-A: Magnetic resonance image showing increased thickness of the donor site twenty-one months after removal of the tissue for the graft.
|
|
View larger version (91K):
[in this window]
[in a new window]
|
Fig. 4-A: Magnetic resonance image showing an increased cross-sectional area of the donor site (midway between the patellar and tibial insertions) twenty-one months after removal of the graft.
|
|
View larger version (85K):
[in this window]
[in a new window]
|
Fig. 4-B: Magnetic resonance image of the contralateral, control ligament, made at tha same relative position and photographic magnification.
|
|
Histological Study and Evaluation with Transmission Electron Microscopy
Histologically, the control tissue demonstrated a consistent pattern of well defined, longitudinally oriented collagen fascicles; a thin tissue septum; myelinated nerve bundles; sparse cellularity; and a small cross-sectional area (Figs. 5-A and 5-B). The repair tissue did not duplicate this normal microanatomy of the patellar ligament. Examination of histological sections through the donor site revealed that a thick collagenous scar tissue had filled the defect (Figs. 6-A and 6-B). The proximal, middle, and distal portions of the donor site demonstrated ill defined fascicles with a woven collagen pattern, a markedly thickened tissue septum, and collagen fibrils that were poorly aligned with the longitudinal axis of the patellar ligament. Well defined bundles of collagen fascicles, with normal cellularity and robust vascular patterns, were seen on either side of the donor site. A narrow spicule of fibrocartilage-like tissue was observed at the distal pole of the patella and extending distally one-third of the distance of the patellar ligament.
View larger version (72K):
[in this window]
[in a new window]
|
Fig. 5-A Low-power micrograph of the middle portion of a control ligament in cross section, demonstrating the normal arrangement of fascicles of a regular size, a thin connective-tissue septum, and a relatively small cross-sectional area (original magnification x 1.75).
|
|
View larger version (154K):
[in this window]
[in a new window]
|
Fig. 5-B Higher-power micrograph of the same ligament in cross section. In addition to the normal arrangement of fascicles (F), blood vessels are seen (arrows) in loose tissue adjacent to the fascicles (original magnification x 10).
|
|
View larger version (70K):
[in this window]
[in a new window]
|
Fig. 6-A Low-power micrograph of the middle portion of a donor ligament twenty-one months after removal of the graft. The central portion consists of several poorly defined fascicles surrounded by a think, vascular connective tissue. Peripheral to this area, the collagen is arranged in well defined fibers. The cross-sectional area is increased compared with that of the control ligament in Figs. 5-A and 5-B (original magnification x 1.75).
|
|
View larger version (143K):
[in this window]
[in a new window]
|
Fig. 6-B Higher-power micrograph of the same ligament. The donor site contains poorly defined large collagenous bundles surrounded by a thick connective tissue. There are fewer vascular elements than in the control tissue and no evidence of inflammatory or other reactions (original magnification x 10).
|
|
Transmission electron microscopy revealed that the repair tissue was composed mainly of collagen fibrils with a small diameter (range, fifty to 100 nanometers) (Figs. 7-A, 7-B, Figs. 7-C, Figs. 8-A, Figs. 8-B, and 8-C). A few collagen fibrils with a large diameter (range, 300 to 350 nanometers) were observed at the central portion of the proximal aspect of the donor site. In the control ligaments, fibrils with a larger diameter (range, 100 to 250 nanometers) represented a high percentage of the total collagen fibril area.
View larger version (18K):
[in this window]
[in a new window]
|
Figs. 7-A, 7-B, and 7-C: Graphs of collagen fibril size as per cent distribution for each specimen location in the repair tissue of the donor site (solid bars) and in the control tissue (hatched bars). Fibrils with a small diameter (range, fifty to 100 nanometers) were consistently observed in all locations of the repair tissue. * = p < 0.01 and ** = p < 0.001 compared with the control values, as determined with use of the Tukey statistic. Figs. 7-A: Specimens from the proximal part of the patellar ligament just distal to the patellar insertion.
|
|
View larger version (18K):
[in this window]
[in a new window]
|
Fig. 7-C Specimens from the distal part of the patellar ligament just proximal to the tibial insertion.
|
|
View larger version (18K):
[in this window]
[in a new window]
|
Figs. 8-A, 8-B, and 8-C: Graphs of collagen fibril cross-sectional area as per cent of total fibril area at each specimen location in the repair tissue of the donor site (solid bars) and in the control tissue (hatched bars). A large increase in the number of fibrils with a small diameter is necessary to affect the percentage of the total area that they represent. Fig. 8-A: Specimens from the proximal part of the patellar ligament just diatal to the patellar insertion.
|
|
|
Discussion
|
|---|
Many surgeons prefer the central one-third bone-patellar ligament-bone autogenous graft for reconstruction of the anterior cruciate ligament because of its strength at procurement, the ease with which each end of the graft can be fixed to bone, and the quality of this osseous fixation. Some surgeons have proposed the use of the same donor site, after a period of time, to obtain a graft for subsequent revision of the reconstruction. In a recent case report describing a patient who had had a previous bilateral reconstruction, the previous donor site was used to obtain a new graft16. In a series of nine patients, the reconstituted patellar ligament was used to revise a reconstruction of the anterior cruciate ligament six to eighteen months after the initial graft had been procured; there were no failures of the graft at the two-year follow-up examination13. In our experience with five patients who were managed with a patellar ligament graft procured from a previous donor site, one graft had inadequate osseous attachments, which necessitated other than interference fixation. We believe that surgeons who propose reuse of previous donor sites should consider combining the initial procurement of the patellar ligament with bone-grafting. Bone-grafting was not performed in the present animal study, and the defects left by the bone plugs did not fill in with new bone.
In the present study, we demonstrated that the defect at the donor site of the patellar ligament graft filled with scar repair tissue. The tensile properties of this new tissue were significantly decreased compared with those of the controls twenty-one months after procurement of the graft. The cross-sectional area of the site from which the central six millimeters had been removed increased a mean of 42 per cent compared with that of the controls, and this increase, which was due to thickness, was significant (p < 0.05). The cross-sectional area of the whole reconstituted patellar ligament in the donor limb was significantly increased (p < 0.001). The maximum force to failure and the ultimate stress to failure were significantly reduced (p < 0.001) compared with those of the controls. These observations are consistent with those of shorter-term studies of changes at the donor sites in dogs5,18, rabbits3, goats12, and humans2,7,20.
The findings on magnetic resonance imaging in the current study indicated that, twenty-one months after removal of the graft, the signal had nearly returned to that of normal patellar ligament. This is similar to the experience reported with humans7,20, in whom the signal of the patellar ligament appeared similar to that of the normal, contralateral ligament by eighteen to twenty-four months postoperatively. The restoration of the magnetic resonance imaging signal may lead to the assumption that the properties of the remodeled tissue were the same as those of the control ligaments. This was not the case in our goat model.
The donor site consistently demonstrated scar tissue in which the collagenous fibers and fascicles were poorly organized and were not oriented longitudinally. The site from which the graft had been taken was surrounded by thick connective tissue. The neurovascular pattern in the scar tissue was not as well organized as that in the normal ligaments.
It appeared that the repair tissue was composed mainly of collagen fibrils of small diameter, in the fifty-to-100-nanometer range. While a few collagen fibrils with a large diameter were observed in some sections, these were believed to be native patellar ligament fibrils that had been pulled into the repair site with the sutures used to appose the ligament margins loosely. The number of fibrils with a small diameter was increased in all of the specimens from the donor site and, to a lesser degree, in specimens from the proximal-exterior portion of the controls. These changes in the controls may have been due to altered loading postoperatively15. An increase in the number of fibrils with a small diameter as a result of exercise was reported in anterior cruciate ligaments from rats9.
In the present study, we addressed the question of whether the repair tissue at the site of procurement of a central one-third patellar ligament graft will regenerate to its original strength—that is, to its original structural and material properties—during a twenty-one-month period. The remaining medial and lateral one-third of the patellar ligament did not influence the regeneration of native ligament. The normal bimodal size pattern of the collagen fibrils was not present in the repair tissue. Instead, the collagen fibrils had small diameters, as are seen in scar tissue. Morphological changes were present in the entire ligament, but the more dramatic changes were seen at the site from which the central six millimeters had been removed.
An issue that deserves additional evaluation is the fate of a graft consisting of this altered repair tissue procured from a previous donor site. It has been reported that autogenous and allogenic patellar ligament grafts used in reconstruction of the anterior cruciate ligament remodel and the original collagen fibrils with large diameters are replaced with fibrils with small diameters12. The incorporated grafts are weaker than they were immediately after procurement9,12. According to our observations, the strength of repair tissue obtained from a previous donor site for use as a graft is 50 per cent less than that of similar control tissue immediately after procurement. Once replanted in the joint, this graft probably undergoes remodeling. It is not known how this remodeling ultimately would affect the properties of the graft.
Additional investigation of the qualities of grafts procured from previous donor sites for repair of the anterior cruciate ligament is needed. At this time, we believe that reuse of the central one-third of the patellar ligament may result in an ultimately weaker graft than if normal patellar ligament were used. We suggest that the hamstring tendons or the contralateral patellar ligament be used instead.
NOTE: The authors thank William Bradley, M.D., Ph.D., for assistance in the performance and interpretation of the magnetic resonance images. They also thank David Van Sickle, D.V.M., Ph.D., Department Head of the Department of Anatomy, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana, for the preparation and interpretation of the histological specimens.
|
Footnotes
|
|---|
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
536 East Arrellega Street, Santa Barbara, California 93103.
2760 Atlantic Avenue, Long Beach, California 90806.
|
References
|
|---|
-
American Veterinary Medical Association Panel on Euthanasia: 1986 report. J. Am. Vet. Med. Assn., 188: 252-268, 1986.[Medline]
-
Berg, E. E.: Intrinsic healing of a patellar tendon donor site defect after anterior cruciate ligament reconstruction. Clin. Orthop., 278: 160-163, 1992.
-
Beynnon, B. D.; Proffer, D.; Drez, D. J.Jr.; Stankewich, C. J.; and Johnson, R. J.: Biomechanical assessment of the healing response of the rabbit patellar tendon after removal of its central third. Am. J. Sports Med., 23: 452-457, 1995.[Abstract/Free Full Text]
-
Bonamo, J. J.; Krinick, R. M.; and Sporn, A. A.: Rupture of the patellar ligament after use of its central third for anterior cruciate reconstruction. A report of two cases. . J. Bone and Joint Surg., 66-A: 1294-1297, Oct. 1984.[Free Full Text]
-
Burks, R. T.; Haut, R. C.; and Lancaster, R. L.: Biomechanical and histological observations of the dog patellar tendon after removal of its central one-third. Am. J. Sports Med., 18: 146-153, 1990.[Abstract/Free Full Text]
-
Cabaud, H. E.; Feagin, J. A.; and Rodkey, W. G.: Acute anterior cruciate ligament injury and augmented repair. Am. J. Sports Med., 8: 395-401, 1980.[Abstract/Free Full Text]
-
Coupens, S. D.; Yates, C. K.; Sheldon, C.; and Ward, C.: Magnetic resonance imaging evaluation of the patellar tendon after use of its central one-third for anterior cruciate ligament reconstruction. Am. J. Sports Med., 20: 332-335, 1992.[Abstract/Free Full Text]
-
Daniel, D. M.; Stone, M. L.; and Riehl, B.: Ligament surgery. The evaluation of results. In Knee Ligaments. Structure, Function, Injury, and Repair, pp. 521-534. Edited by D. M. Daniel, W. H. Akeson, and J. J. O'Connor. New York, Raven Press, 1990.
-
Frank, C.; Woo, S.; Andriacchi, T.; Brand, R.; Oakes, B.; Dahners, L.; DeHaven, K.; Lewis, J.; and Sabiston, P.: Normal ligament: structure, function and composition. In American Academy of Orthopaedic Surgeons. Symposium on Injury and Repair of the Musculoskeletal Soft Tissues, pp. 69-82. Edited by S. L-Y. Woo and J. A. Buckwalter. Park Ridge, Illinois, The American Academy of Orthopaedic Surgeons, 1987.
-
Harden, G. T., and Bach, B. R., Jr.: Distal rupture of the infrapatellar tendon after use of its central one third for ACL reconstruction. Am. J. Knee Surg., 5: 140-143, 1992.
-
Hughston, J. C.: Complications of anterior cruciate ligament surgery. Orthop. Clin. North America, 16: 237-240, 1985.[Medline]
-
Jackson, D. W.; Grood, E. S.; Goldstein, J. D.; Rosen, M. A.; Kurzweil, P. R.; Cummings, J. F.; and Simon, T. M.: A comparison of patellar tendonautograft and allograft used for anterior cruciate ligament reconstruction in the goat model. Am. J. Sports Med., 21: 176-185, 1993.[Abstract/Free Full Text]
-
Johnson, D.: Personal communication, 1994.
-
Jones, K. G.: Reconstruction of the anterior cruciate ligament. A technique using the central one-third of the patellar ligament. J. Bone and Joint Surg., 45-A: 925-932, July 1963.[Free Full Text]
-
Kamps, B. S.; Linder, L. H.; DeCamp, C. E.; and Haut, R. C.: The influence of immobilization versus exercise on scar formation in the rabbit patellar tendon after excision of the central third. Am. J. Sports Med., 22: 803-811, 1994.[Abstract/Free Full Text]
-
Karns, D. J.; Heidt, R. S., Jr.; Holladay, B. R.; and Colosimo, A. J.: Case report: revision anterior cruciate ligament reconstruction. Arthroscopy, 10: 148-151, 1994.[Medline]
-
Langan, P., and Fontanetta, A. P.: Rupture of the patellar tendon after use of its central third. Orthop. Rev., 16: 317-321, 1987.[Medline]
-
Linder, L. H.; Sukin, D. L.; Burks, R. T.; and Haut, R. C.: Biomechanical and histological properties of the canine patellar tendon after removal of its medial third. Am. J. Sports Med., 22: 136-142, 1994.[Abstract/Free Full Text]
-
McCarroll, J. R.: Fracture of the patella during a golf swing following reconstruction of the anterior cruciate ligament. A case report. Am. J. Sports Med., 11: 26-27, 1983.[Free Full Text]
-
Nixon, R. G.; SeGall, G. K.; Sax, S. L.; Cain, T. E.; and Tullos, H. S.: Reconstitution of the patellar tendon donor site after graft harvest. Clin. Orthop., 317: 162-171, 1995.
-
Sachs, R. A.; Daniel, D. M.; Stone, M. L.; and Garfein, R. F.: Patellofemoral problems after anterior cruciate ligament reconstruction. Am. J. Sports Med., 17: 760-765, 1989.[Abstract/Free Full Text]
-
Tibone, J. E., and Antich, T. J.: A biomechanical analysis of anterior cruciate ligament reconstruction with the patellar tendon. A two year followup. Am. J. Sports Med., 16: 332-335, 1988.[Abstract/Free Full Text]
-
Wallenböck, E.: Ligamentum patellae-Ruptur—eine Spätkomplikation nach Entnahme eines Knochen-Sehnen-Knochen-Transplantats als Kreuzbandersatz?. Langenbecks Arch. Chir., 378: 339-340, 1993.[Medline]
 CiteULike  Connotea  Del.icio.us  Facebook  Technorati  Twitter What's this?
This article has been cited by other articles:
|
|
|
|
 
K. T. Jensen, D. P. Rabago, T. M. Best, J. J. Patterson, and R. Vanderby Jr
Response of Knee Ligaments to Prolotherapy in a Rat Injury Model
Am. J. Sports Med.,
July 1, 2008;
36(7):
1347 - 1357.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. Liden, T. Movin, L. Ejerhed, N. Papadogiannakis, E. Blomen, K. Hultenby, and J. Kartus
A Histological and Ultrastructural Evaluation of the Patellar Tendon 10 Years After Reharvesting Its Central Third
Am. J. Sports Med.,
April 1, 2008;
36(4):
781 - 788.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. Svensson, T. Movin, L. Rostgard-Christensen, E. Blomen, K. Hultenby, and J. Kartus
Ultrastructural Collagen Fibril Alterations in the Patellar Tendon 6 Years After Harvesting Its Central Third
Am. J. Sports Med.,
February 1, 2007;
35(2):
301 - 306.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. V. West and C. D. Harner
Graft Selection in Anterior Cruciate Ligament Reconstruction
J. Am. Acad. Ortho. Surg.,
May 1, 2005;
13(3):
197 - 207.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. S. Gill, M. A. Turner, T. C. Battaglia, H. T. Leis, G. Balian, and M. D. Miller
Semitendinosus Regrowth: Biochemical, Ultrastructural, and Physiological Characterization of the Regenerate Tendon
Am. J. Sports Med.,
July 1, 2004;
32(5):
1173 - 1181.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. J. Colosimo, R. S. Heidt Jr, J. A. Traub, and R. L. Carlonas
Revision Anterior Cruciate Ligament Reconstruction with a Reharvested Ipsilateral Patellar Tendon
Am. J. Sports Med.,
November 1, 2001;
29(6):
746 - 750.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. Kartus, T. Movin, N. Papadogiannakis, L. R. Christensen, S. Lindahl, and J. Karlsson
A Radiographic and Histologic Evaluation of the Patellar Tendon after Harvesting Its Central Third
Am. J. Sports Med.,
March 1, 2000;
28(2):
218 - 226.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
Top
Abstract
Introduction
