Magnetic resonance imaging evaluation of the patellar tendon after use of its central one-third for anterior cruciate ligament reconstruction

Near complete quadriceps tendon healing 2 years following harvest in anterior cruciate ligament reconstruction

PURPOSE

Despite the recent increase in the use of quadriceps tendon (QT) autograft in anterior cruciate ligament reconstruction (ACLR); however, there remains a paucity of literature evaluating the postoperative morphology of the QT. The present study aimed to determine the postoperative morphologic change of the QT at a minimum of 2 years following harvesting during ACLR.

METHODS

Patients who underwent ACLR with QT autograft and underwent magnetic resonance imaging (MRI) at a minimum of 2 years following harvesting were retrospectively included in the study. The anterior-to-posterior (A-P) thickness, medial-to-lateral (M-L) width, cross-sectional area (CSA), and signal/noise quotient (SNQ) of the QT were assessed at 5 mm, 15 mm, and 30 mm proximal to the superior pole of the patella on MRI. The CSA was adjusted by the angle between the QT and the plane of the axial cut based on a cosine function (adjusted CSA). The A-P thickness, M-L width, adjusted CSA, and SNQ were compared pre- and postoperatively. In addition, defects or scar tissue formation in the harvest site were investigated on postoperative MRI.

RESULTS

Thirty patients were recruited for the study. The mean duration between postoperative MRI and surgery was 2.8 ± 1.1 years. The mean A-P thickness was 10.3% and 11.9% larger postoperatively at 5 mm and 15 mm, respectively. The mean M-L width was 7.3% and 6.5% smaller postoperatively at 5 mm and 15 mm, respectively. There were no significant differences in the adjusted CSA between pre- and post-operative states (275.7 ± 71.6 mm2 vs. 286.7 ± 91.8 mm2, n.s.). There was no significant difference in the postoperative change in the SNQ of the QT at all assessment locations. Defect or scar tissue formation at the harvest site was observed in 4 cases (13.3%), and 5 cases (16.6%), respectively.

CONCLUSION

At a minimum of 2 years following QT harvest during ACLR, the QT became slightly thicker and narrower (approximately 11% and 7%, respectively). While the current study demonstrates that QT re-harvesting can be considered due to nearly normalized tendon morphology, future histological and biomechanical studies are required to determine the re-harvesting potential of the QT.

LEVEL OF EVIDENCE

IV.

Bone Grafting the Patellar Defect After Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction Decreases Anterior Knee Morbidity: A Systematic Review

PURPOSE

The aim of this systematic review was to evaluate the impact of bone grafting of patellar defects on reported anterior knee morbidity and subjective outcomes after bone-patellar tendon-bone autograft reconstruction of the anterior cruciate ligament.

METHODS

A systematic electronic search of MEDLINE, Embase, Web of Science, and the Cochrane Library was carried out. All English-language prospective randomized clinical trials published from January 1, 2000, to July 24, 2020, were eligible for inclusion. All studies addressing patellar defect grafting were eligible for inclusion regardless of the timing of surgery, graft type, surgical technique, or rehabilitation protocol.

RESULTS

A total of 39 studies with 1,955 patients were included for analysis. There were 796 patients in the no patellar grafting (NPG) group, with a mean age range of 22.7 to 33.0 years, and 1,159 patients in the patellar grafting (PG) group, with a mean age range of 17.8 to 34.7 years. The visual analog scale pain score ranged from 1.2 to 5.1 in the NPG group compared with 0.3 to 3.7 in the PG group. The proportion of patients with anterior knee pain ranged from 19% to 81% in the NPG group and from 15% to 32% in the PG group. Moderate to severe kneeling pain was reported in 22% to 57% of patients in the NPG group and 10% of those in the PG group. The percentage of patients with at least 3° of extension loss ranged from 4% to 43% in the NPG group and from 2% to 11% in the PG group.

CONCLUSIONS

PG favors decreased anterior knee pain, kneeling pain, and extension loss compared with non-grafted defects; however, the functional outcomes are comparable. Owing to the heterogeneity in reporting, statistical conclusions could not be drawn.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Peroneus Longus Tendon Autograft for Anterior Cruciate Ligament Reconstruction: A Safe and Effective Alternative in Nonathletic Patients

Introduction

Anterior cruciate ligament (ACL) is a common injury which has been conventionally managed by various graft reconstruction using bone patellar tendon bone, or quadruple hamstring autograft, to name a few. However, all these grafts are associated with many complications. Lately, peroneus longus tendon (PLT) autograft has shown promising results in this field, although there is still a dearth of data on its use. We, therefore, aimed at carrying out a study to evaluate the functional outcome and knee stability results of ACL reconstruction using PLT graft.

Patients and Methods

Patients with a completely torn ACL were included in the study. The PLT was harvested, and graft length, thickness, and harvesting time were noted intraoperatively. Knee stability and functional scores were evaluated clinically and using Lachman test (primarily) and KT-2000 arthrometer and subjectively with International Knee Documentation Committee (IKDC) score at 6, 12, and 24 months (secondary outcome) postoperatively. Ankle scores were also recorded by making use of American Orthopedic Foot and Ankle Score (AOFAS)-Hindfoot Scale.

Results

Forty-eight patients met the inclusion criteria. The graft harvest time was 7.4 min (5-9 min). The mean thickness of the graft on doubling was 7.9 mm (7-9 mm). Ninety-six percent of the patients were satisfied with their results of the knee surgery, and 95% of the patients had no complaints of ankle joint. The mean IKDC score postoperatively was 78.16 ± 6.23, and the mean AOFAS score was 98.4 ± 4.1. None of the patients had any neurovascular deficit.

Conclusion

ACL reconstruction using PLT graft yields a good functional score (IKDC, KT-2000 arthrometer) even at 2-year follow-up. It is a safe and effective autograft option for ACL reconstruction.

Scaffold-Free Bio-3D Printing Using Spheroids as "Bio-Inks" for Tissue (Re-)Construction and Drug Response Tests

In recent years, scaffold-free bio-3D printing using cell aggregates (spheroids) as "bio-inks" has attracted increasing attention as a method for 3D cell construction. Bio-3D printing uses a technique called the Kenzan method, wherein spheroids are placed one-by-one in a microneedle array (the "Kenzan") using a bio-3D printer. The bio-3D printer is a machine that was developed to perform bio-3D printing automatically. Recently, it has been reported that cell constructs can be produced by a bio-3D printer using spheroids composed of many types of cells and that this can contribute to tissue (re-)construction. This progress report summarizes the production and effectiveness of various cell constructs prepared using bio-3D printers. It also considers the future issues and prospects of various cell constructs obtained by using this method for further development of scaffold-free 3D cell constructions.

Histological evaluation of tendon formation using a scaffold-free three-dimensional-bioprinted construct of human dermal fibroblasts under in vitro static tensile culture

Introduction

Tendon tissue engineering requires scaffold-free techniques for safe and long-term clinical applications and to explore alternative cell sources to tenocytes. Therefore, we histologically assessed tendon formation in a scaffold-free Bio-three-dimensional (3D) construct developed from normal human dermal fibroblasts (NHDFs) using our Bio-3D printer system under tensile culture in vitro.

Methods

Scaffold-free ring-like tissues were constructed from 120 multicellular spheroids comprising NHDFs using a bio-3D printer. Ring-like tissues were cultured in vitro under static tensile-loading with or without in-house tensile devices (tension-loaded and tension-free groups), with increases in tensile strength applied weekly to the tensile-loaded group. After a 4 or 8-week culture on the device, we evaluated histological findings according to tendon-maturing score and immunohistological findings of the middle portion of the tissues for both groups (n = 4, respectively).

Results

Histology of the tension-loaded group revealed longitudinally aligned collagen fibers with increased collagen deposition and spindle-shaped cells with prolonged culture. By contrast, the tension-free group showed no organized cell arrangement or collagen fiber structure. Additionally, the tension-loaded group showed a significantly improved tendon-maturing score as compared with that for the tension-free group at week 8. Moreover, immunohistochemistry revealed tenascin C distribution with a parallel arrangement in the tensile-loading direction at week 8 in the tension-loaded group, which exhibited stronger scleraxis-staining intensity than that observed in the tension-free group at weeks 4 and 8.

Conclusions

The NHDF-generated scaffold-free Bio-3D construct underwent remodeling and formed tendon-like structures under tensile culture in vitro.

Sex Differences in the Residual Patellar Tendon After Harvesting Its Central Third for Anterior Cruciate Ligament Reconstruction

OBJECTIVES

Some studies have found that sex can affect the clinical results after anterior cruciate ligament reconstruction. We hypothesized that sex would significantly affect the healing of the postoperative patellar tendon. This study evaluated the patellar tendon after bone-patellar tendon-bone autograft harvest, specifically with regard to sex-dependent differences.

METHODS

At 6 months postoperatively, an ultrasonographic evaluation was performed. We measured the residual donor site gap width between tendon tissues and the thickness of newly formed nontendinous tissue in the gap. In addition, the cross-sectional area of tendon tissue was measured. The ratios between the operated and contralateral sides were calculated, and the sexes were compared. A paired Student t test was performed, with P < .05 considered statistically significant.

RESULTS

The population of 52 patients (32 male and 20 female) had a mean age ± SD of 23 ± 8 years. We observed no significant sex-dependent differences in the residual donor site gap and the thickness of newly formed nontendinous tissue when calculating ratios to the contralateral tendon. The mean cross-sectional area of tendon tissue was 101 ± 26 mm² (male, 114 ± 26 mm² ; female, 80 ± 16 mm² ). When the ratios to the contralateral tendon were calculated, male patients had significantly higher cross-sectional area ratios than female patients (male, 124% ± 20%; female, 100% ± 19%, P = .024).

CONCLUSIONS

We have reported a dramatic increase in the cross-sectional area of patellar tendon tissue during the first 6 months after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft, which was more prominent in male patients than in female patients. This difference might have contributed to the sex-dependent variation in clinical outcomes.

Healing of donor site in bone-tendon-bone ACL reconstruction accelerated with plasma rich in growth factors: a randomized clinical trial

PURPOSE

To determine whether the use of plasma rich in growth factors accelerates healing of the donor site in bone-tendon-bone anterior cruciate ligament (ACL) reconstruction (patellar graft). The use of the patellar graft presents post-operative problems such as anterior knee pain, which limits its use and leads to preference being taken for alternative grafts.

METHODS

A double-blind, randomized, clinical trial was performed comparing two groups of patients who underwent ACL reconstruction using patellar tendon graft and comparing the use of plasma rich in growth factors at the donor site after graft harvest in terms of local regeneration by ultrasound assessment.

RESULTS

The plasma rich in growth factors group shows earlier donor site regeneration in comparison with the control group (2 months earlier), with significant differences in the first 4 months of the follow-up.

CONCLUSION

The application of plasma rich in growth factors shows accelerated tissue regeneration processes with respect to the control group. This fact, together with the previously published with similar conclusions, can create a knowledge basis in order to set out new recovery guidelines following ACL reconstruction.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Closure of patellar tendon defect in anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft: systematic review of randomized controlled trials

PURPOSE

This study aimed to systematically review the highest level of evidence on anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BPTB) autografts with patellar tendon defect closure versus no closure after surgery.

METHODS

We performed a systematic review of multiple medical databases using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Level I and Level II randomized controlled trials comparing patellar tendon defect closure to no closure during ACL reconstruction with BPTB autografts were included. Two independent reviewers analyzed all studies. Descriptive statistics were calculated. Study methodological quality was analyzed using the Modified Coleman Methodology Score (MCMS) and Jadad scale.

RESULTS

Four studies with a combined 221 patients (154 male patients and 67 female patients) with an average age of 26.6 ± 2.4 years (range, 17 to 54 years) were included. All studies randomized patients before surgery into ACLR with BPTB autografts either with patellar tendon defect closure or without closure. There were no differences in clinical outcomes (Lysholm score, Tegner scale, International Knee Documentation Committee [IKDC] classification, modified Larsen score, and Lauridsen rating) between groups. There were no significant differences in knee pain between groups. All studies reported imaging findings of the patellar tendon defect, with 2 studies showing no difference in appearance between groups, one study showing excessive scar formation with defect repair, and one study showing improved restoration of normal tendon appearance with defect repair. The overall quality of the studies was poor, with all studies scoring less than 46 (average, 40.5 ± 4.7) on the MCMS and scoring 1 on the Jadad scale.

CONCLUSIONS

Based on this systematic review of 4 randomized trials, there are no statistically significant or clinically relevant differences in outcomes between patients who have the patellar tendon defect closed and those who have it left open after ACLR with BPTB autografts. The methodology of the included studies limits the interpretation of the data, as evidenced by low MCMS and Jadad scores.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and Level II studies.

Revision ACL reconstruction using contralateral hamstrings

PURPOSE

Due to the increasing number of primary anterior cruciate ligament (ACL) reconstructions, the need for revision surgery has risen. The aim of this study was to evaluate the use of contralateral doubled semitendinosus and gracilis tendon (DGST) for revision anterior cruciate ligament reconstruction.

METHODS

Twelve patients undergoing revision ACL reconstruction with hamstring tendon were examined at an average follow-up of 3 years. All patients underwent a thorough subjective and objective evaluation, which included a KT-1000 arthrometric evaluation, and a radiographic examination.

RESULTS

Subjective evaluation yielded a median score of 5.5 (range 2-9) on the Tegner activity scale. The mean Lysholm score was 95 (SD 9.5), and the mean subjective IKDC 2000 score was 95.4 (SD 7.8). At physical examination, a negative Lachman test was found in ten patients; one patient had a positive Lachman test with a firm end-point, and one other patient had a clearly positive Lachman test. Two patients had a grade 1+ on pivot shift testing. Only 1 patient showed a side-to-side difference more than 5 mm at the maximum manual KT-1000 arthrometer. Three patients (25 %) showed initial signs of osteoarthritis.

CONCLUSIONS

The results of the study show that the use of hamstring tendons harvested from the unaffected knee represents a valid option for revision surgery following a failed primary ACL reconstruction using DGST grafts.

LEVEL OF EVIDENCE

IV.

Bioreactor design for tendon/ligament engineering

Tendon and ligament injury is a worldwide health problem, but the treatment options remain limited. Tendon and ligament engineering might provide an alternative tissue source for the surgical replacement of injured tendon. A bioreactor provides a controllable environment enabling the systematic study of specific biological, biochemical, and biomechanical requirements to design and manufacture engineered tendon/ligament tissue. Furthermore, the tendon/ligament bioreactor system can provide a suitable culture environment, which mimics the dynamics of the in vivo environment for tendon/ligament maturation. For clinical settings, bioreactors also have the advantages of less-contamination risk, high reproducibility of cell propagation by minimizing manual operation, and a consistent end product. In this review, we identify the key components, design preferences, and criteria that are required for the development of an ideal bioreactor for engineering tendons and ligaments.

The reharvested patellar tendon has the potential for ligamentization when used for anterior cruciate ligament revision surgery

PURPOSE

The aim of the present study was to make an in-depth clinical, radiographical, and histological evaluation of patients who underwent anterior cruciate ligament (ACL) revision surgery with reharvested central third patellar tendon autograft.

METHODS

Four patients (two women and two men) underwent ACL revision surgery with reharvested patellar tendon autograft 71 (66-120) months after the primary reconstruction. The patients were followed prospectively and underwent a clinical examination and magnetic resonance imaging (MRI) at two and 10 years. Furthermore, they underwent a second-look arthroscopy involving a biopsy procedure from the reconstructed ACL 3 years after revision surgery.

RESULTS

The clinical results were poor both at two and 10 years, but the knees were stable and had a firm endpoint in all four patients in the Lachman test. At the second-look arthroscopy, the graft appeared macroscopically normal in all four patients. Histologically two patients had a normal or close to normal appearance of the reconstructed ACL with no or slight increase in cellularity and vascularity. Two patients had a marked increase in cellularity and vascularity, and the findings revealed that ligamentization was present in all four patients.

CONCLUSIONS

The clinical outcome 10 years after ACL revision surgery was poor in these four patients. In contrast, the reharvested patellar tendon appeared close to normal on MRI, and the second-look arthroscopy with the concomitant histological findings revealed that the grafts were viable 3 years after revision. Therefore, the reharvested patellar tendon seems to have the potential for ligamentization when used for ACL revision surgery.

LEVEL OF EVIDENCE

Case series, Level IV.

Anterior cruciate ligament reconstruction using the medial third of the patellar tendon

PURPOSE

To evaluate the mid-term outcome of anterior cruciate ligament (ACL) reconstruction using the medial third of the patellar tendon as the bone-patellar tendon-bone (BPTB) graft.

METHODS

79 men (34 right knees and 45 left knees) aged 20 to 52 (mean, 28) years underwent ACL reconstruction using the medial third of the patellar tendon with bone plugs and were followed up for a minimum of 3 years. Stability was assessed using the Lachman test and the pivot shift test. The range of motion, donor-site symptoms, Lysholm knee score, and International Knee Documentation Committee (IKDC) score were also recorded.

RESULTS

In terms of stability, only 4 patients had a grade-2 laxity postoperatively, compared to all having a grade-2 or -3 laxity preoperatively. Regarding the range of motion, extension loss was <3º in 76 patients and 3º to 5º in 3, whereas flexion loss was <5º in 73 patients, 5º to 15º in 5, and 16º to 25º in one. No patient had patellar tendon rupture/shortening, patellar fracture, or patellar maltracking. The mean Lysholm knee score improved from 48 to 92 (p<0.0001); scores were excellent (>90) in 46 patients and good (83-90) in 32 patients. The overall IKDC score was grade A (normal) in 9 patients, grade B (near normal) in 66, and grade C (abnormal) in 4. Three of the latter patients had osteoarthritic changes and pain on minimal physical activity. Only one patient had a sensation of partial giving way during moderate physical activity. 20% of the patients had anterior knee pain.

CONCLUSION

Outcome of ACL reconstruction using the medial third of the patellar tendon was comparable to that using the central third of the patellar tendon. In addition, there were no instances of patellar tendon rupture/shortening, patellar fracture, or patellar maltracking.

Anterior cruciate ligament graft reconstruction: clinical, technical, and imaging overview

The anterior cruciate ligament (ACL) is one of the most frequently torn ligaments of the knee. With more than 100,000 ACL reconstructions performed yearly in the United States, evaluation of ACL grafts with magnetic resonance imaging is a common occurrence in daily clinical practice. Anterior cruciate ligament reconstructions vary from single bundle, double bundle, selective bundle, and physeal-sparing techniques. Complications of ACL graft reconstructions include graft tears, graft laxity, arthrofibrosis, and hardware failure or migration. This article offers a comprehensive review of ACL reconstruction for the consulting radiologist.

Evaluation of knee stability with use of a robotic system

In our research center, we have developed and utilized a novel robotic/universal force-moment sensor testing system to gain quantitative data on multiple-degree-of-freedom kinematics of the knee simultaneously with data on the in situ forces in normal and repaired soft tissues. In particular, we have investigated the complex interaction of the anteromedial and posterolateral bundles of the anterior cruciate ligament as well as several key biomechanical variables in anterior cruciate ligament reconstruction, such as graft selection and femoral tunnel placement (both of which impact knee stability). For example, both the bone-patellar tendon-bone and quadrupled hamstrings tendon autografts restored anterior stability but were insufficient in gaining rotatory stability. In a follow-up study, we have shown that a more laterally placed graft was beneficial and could improve these outcomes. Such findings led to additional investigation in which the biomechanical advantages of double-bundle anterior cruciate ligament reconstruction were demonstrated. However, a more laterally placed autograft at the femoral insertion of the posterolateral bundle also worked well, especially when the knee was nearly at full extension (a position in which the anterior cruciate ligament is needed most). At present, we are moving forward by obtaining in vivo kinematics data and then repeating those kinematics exactly to obtain new data with use of the robotic/universal force-moment sensor testing system in order to gain further insight regarding the function of the anterior cruciate ligament and anterior cruciate ligament replacement grafts in vivo. In parallel, we are developing a mathematical model of the knee and validating the computational model with experimental data. The combined approach will yield new and relevant information, including the stress and strain distribution in the anterior cruciate ligament and anterior cruciate ligament grafts. This will facilitate a better understanding of the function of the anterior cruciate ligament and a scientifically based design of surgical procedures and postoperative rehabilitation protocols that will lead to better patient outcomes.

A histological and ultrastructural evaluation of the patellar tendon 10 years after reharvesting its central third

PURPOSE

This study was undertaken to evaluate the histologic and ultrastructural characteristics of the patellar tendon 10 years after reharvesting its central third.

HYPOTHESIS

In the long term, after its central third is reharvested, the patellar tendon does not regain a normal histological and ultrastructural appearance.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Twelve consecutive patients (4 women, 8 men) who underwent anterior cruciate ligament revision surgery using reharvested ipsilateral patellar tendon autografts were included in the study. Percutaneous biopsy samples were obtained from the central and lateral parts of the patellar tendon under ultrasonographic guidance at a median of 116 months (range, 102-127 months) after the revision procedure. Eleven biopsy specimens from asymptomatic patellar tendons obtained from open anterior cruciate ligament reconstructions served as controls. The histologic characteristics and the presence of glycosaminoglycans were assessed using a light microscope, and the ultrastructure was assessed using a transmission electron microscope.

RESULTS

The histological evaluation revealed deterioration in fiber structure, increased cellularity, and increased vascularity in both the central and peripheral parts of the reharvested patellar tendon specimens compared with normal tendon specimens. No difference in the amount of glycosaminoglycans was seen in specimens from either part of the reharvested patellar tendons and the control specimens. The ultrastructural evaluation revealed that all the control specimens had a normal morphologic appearance and a compact extracellular matrix with regularly oriented collagen fibrils. Furthermore, in the control specimens, the fibril diameter was heterogeneous, with all fibril size classes present. Specimens from the central and the lateral part of the reharvested tendon displayed pathological cell appearance and a more heterogeneous extracellular matrix. The lateral specimens from the reharvested tendons also displayed all fibril size classes but with a more homogeneous distribution. In the central specimens, the largest fibril size class was absent.

CONCLUSION

Ten years after its central third was reharvested for anterior cruciate ligament revision surgery, the patellar tendon had not normalized in terms of its histological and ultrastructural appearance.

A literature review of autograft and allograft anterior cruciate ligament reconstruction

Knee anterior cruciate ligament reconstructive surgery has significantly evolved and now includes the option of using an allograft. This has resulted in numerous studies evaluating the advantages and disadvantages of allografts. The purpose of this literature review is to evaluate this research and present important findings to allow the selection of the most appropriate graft source when considering allograft versus autograft reconstruction.

The course of the patellar tendon after reharvesting its central third for ACL revision surgery: a long-term clinical and radiographic study

The choice of the optimal graft for anterior cruciate ligament (ACL) revision surgery is still controversial. Reharvesting the patellar tendon has been suggested as one graft alternative. Our hypothesis was that in the long-term, ACL revision surgery using reharvested patellar tendon autografts would render a good clinical outcome and a normal patellar tendon at the donor site as seen on magnetic resonance imaging (MRI). Fourteen consecutive patients (five women, nine men), who underwent ACL revision surgery using reharvested ipsilateral patellar tendon grafts, were included in the study. They underwent bilateral MRI evaluations of the patellar tendon and were tested for clinical outcome 26 (20-35) and 115 months (102-127) after the revision procedure. On the second occasion, they also underwent standard weight-bearing X-ray examinations. The serial MRI evaluations revealed that the thickness of the patellar tendon at the donor site was significantly increased compared with the non-harvested, normal contralateral side and that the donor-site gap was still visible after 10 years. No significant differences were seen between the 2- and 10-year MRI evaluations. Standard weight-bearing X-ray examinations revealed signs of mild degenerative changes in all patients. Clinical results in terms of the Lysholm score, IKDC evaluation system, one-leg-hop test, KT-1000 laxity test and the knee-walking test revealed no significant differences between the 2- and 10-year assessments. In overall terms, the clinical results were considered to be poor on both occasions. The patellar tendon at the donor site had not normalised 10 years after the reharvesting procedure, as seen on MRI. Furthermore, the clinical results were poor after ACL revision surgery using reharvested patellar tendon autograft.

[MRI after meniscus and cruciate ligament surgery]

Nowadays, due to its high diagnostic accuracy, MR imaging is the method of choice for the evaluation of knee joint disorders pre- and postoperatively. Accurate diagnosis is sometimes possible only if the reporting radiologist has knowledge of the therapeutic procedures and the surgical report. Frequently, further therapeutic management is strongly influenced by MR examinations and radiological reports.

MR imaging evaluation of the postoperative knee: ligaments, menisci, and articular cartilage

The surgical management of knee injuries has increased in recent years. Postoperative magnetic resonance (MR) imaging of the knee following surgical intervention serves an important role in the diagnostic evaluation of patients with recurrent or residual symptoms following surgical intervention. MR imaging additionally assists in the noninvasive documentation of temporal changes at the surgical site potentially reflective of procedural success, or failure. Background understanding of the common surgical procedures performed, their normal postoperative MR imaging appearance, and imaging features of potential procedural complications are essential in the accurate evaluation of patients following prior knee surgery. The focus of the following article is to review the clinical and MR imaging features of the postoperative knee following prior surgical treatment of ligamentous, meniscal, and articular cartilage injuries of the joint.

Evaluation of hamstring strength and tendon regrowth after harvesting for anterior cruciate ligament reconstruction

BACKGROUND

It is generally thought that tissue regeneration and good functional recovery can be expected after anterior cruciate ligament reconstruction using the hamstring tendons. However, persistent strength deficit in deep knee flexion has also been reported.

HYPOTHESIS

Morphologic regeneration of the harvested hamstring tendon is not necessarily associated with its functional recovery.

STUDY DESIGN

Retrospective follow-up study.

METHOD

Twenty-eight patients who underwent anterior cruciate ligament reconstruction with hamstring graft were evaluated after a minimum period of 2 years. Status of tendon regrowth was assessed by magnetic resonance imaging. To specifically analyze the functional deficit after graft harvest, the isometric hamstring strength was examined in a sitting position at 90 degrees of flexion and a prone position at 90 degrees and 110 degrees of flexion. Then, the strength data were correlated with the extent of tendon regeneration.

RESULTS

In 22 of the 28 patients, a regrowth of the semitendinosus tendon was found, whereas regeneration of the gracilis tendon was observed in 13 patients. In the evaluation of hamstring strength, the isometric peak torque was reduced to 86.2%, 54.6%, and 49.1%, respectively, in the aforementioned 3 postures as compared with the contralateral side.

CONCLUSIONS

Significant functional deficit of hamstring strength remains regardless of morphologic regeneration.

MRI evaluation of patellar tendon defect after harvesting its central third

PURPOSE

the purpose of this study was to evaluate defect width of patellar tendon after harvest for anterior cruciate ligament reconstruction.

MATERIALS AND METHODS

we performed MRI at various time interval after graft harvest (2-96 months) on 28 patients who had had reconstruction of the anterior cruciate ligament using mid-third patellar tendon. T1 and T2 weighted axial images were obtained to assess donor site defect of the patellar tendon. Measurement of the defect width was performed at the level of menisci on the axial images. The patients were divided into two groups according to the time interval between operation and imaging. The defect width of patients with short time interval (2-12 months) was compared to the defect width of patients with long time interval (12-96 months).

RESULTS

the average defect width of patients with short time interval was 6.4 mm and it was 2.2 mm for the patients with long time interval. Decreased defect width was obtained from MRI images in the patients with long time interval. Closed donor site defect was detected in 1 out of 14 patients with short time interval and 6 out of 14 patients with long time interval.

DISCUSSION AND CONCLUSION

these results show that there is no complete closure of donor site defect up to 1 year. However, it seems to be nearly complete closure of patellar tendon defect in the long time period.

Revision anterior cruciate ligament reconstruction using the regenerated semitendinosus tendon: analysis of ultrastructure of the regenerated tendon

In this report, we present a case of a college skier who sustained a rerupture of the reconstructed anterior cruciate ligament (ACL) 8 months after surgery in which an autogenous semitendinosus tendon graft was used. At the revision surgery, the harvested semitendinosus tendon appeared to be regrown. Thus the regenerated tendon was reharvested, and in combination with the gracilis tendon, was used as a graft. The electron microscopic examination revealed a difference in fibril diameter between the regenerated tissue and the normal tendon. Although the regenerated semitendinosus tendon could be reharvested, the feasibility of its use for revision surgery is still to be determined.

Three-dimensional computed tomography evaluation of semitendinosus harvest after anterior cruciate ligament reconstruction

PURPOSE

Recent studies have shown the regeneration potential of hamstring tendons harvested for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the morphology of the regenerated semitendinosus tendon using 3-dimensional (3-D) images of volume-rendered multidetector helical computed tomography (MD-CT).

TYPE OF STUDY

Retrospective study on a convenient sample of patients.

METHODS

Eight patients were selected from those with a minimum 2-year follow-up evaluation after ACL reconstruction with hamstring tendons. The harvest site of the semitendinosus tendon was evaluated using 3-D CT, in addition to magnetic resonance imaging (MRI) analysis, at an average of 37 months (range, 27 to 47 months) after surgery.

RESULTS

In 5 of 8 patients, MRI evaluation indicated recurrence of the region with the same signal intensity as the native at the harvest site of the semitendinosus tendon. In these patients, the 3-D image of MD-CT visualized the stringy tendinous tissue regenerated at the harvest site originating from the semitendinosus muscle belly and running in the same pathway as the native tendon. However, the distal part attached into the medial surface of the popliteal fascia. By contrast, in the involved sides of the remaining 3 patients with no detection on MRI, the 3-D CT image showed no tendinous tissue at the harvest site. The remnants of the semitendinosus had reduced or fused into the muscle belly of the semimembranous.

CONCLUSIONS

Using the 3-D CT technique, we could first depict the distinct morphology of the regenerate at the harvest site of the semitendinosus tendon.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Does the patellar tendon normalize after harvesting its central third?: a prospective long-term MRI study

BACKGROUND

The central third of the patellar tendon is the most frequently used autograft for ACL reconstruction.

HYPOTHESIS

The patellar tendon at the donor site would look normal as seen on MRI 6 years after harvesting its central third.

METHODS

Nineteen consecutive patients were included in the study. MRI examinations of the donor site were performed at 6 (5 to 10) weeks, 6 (6 to 8) months, 27 (24 to 29) months, and 71 (68 to 73) months postoperatively. The contralateral normal side was examined only on the first occasion.

RESULTS

The size of the donor-site gap decreased significantly (P = 0.0001) between 6 weeks and 6 years. In most patients, a thinning of the central part of the patellar tendon was still found at 6 years. The thickness of the peripheral patellar tendon was increased, compared with the contralateral healthy side, until 2 years (P = 0.003). On all occasions, the width was increased compared with the contralateral side (P < 0.015).

CONCLUSION

Prospective MRI examinations revealed that the patellar tendon at the donor site had not normalized 6 years after harvesting its central third. The reharvesting of the patellar tendon can therefore not be recommended.

Postoperative evaluation of the knee

New developments and improvements in ligamentous and meniscal surgery and cartilage repair procedures have led to an increased incidence ot these procedures being performed. Subsequently, there has been a corresponding increase in postoperative imaging studies. and it is imperative for radiologists to be comfortable with the normal imaging appearance of these procedures and associated complications.

Anterior cruciate ligament reconstruction with a reharvested bone-patellar tendon-bone graft

We sought to determine the results in patients who underwent revision anterior cruciate ligament reconstruction with a reharvested bone-patellar tendon-bone graft. Preoperative magnetic resonance imaging of the patellar tendon was used to determine the width of the tendon and the quality of the tissue. The section of the tendon harvested included 7 to 8 mm of the regenerated tendon and 2 to 3 mm of previously untouched tendon either medial or lateral to the healed tissue. The mean time from primary graft harvest to reharvest was 71.0 +/- 44 months (range, 32 to 180). An accelerated rehabilitation program was used postoperatively. Objective follow-up of more than 2 years after surgery was available for 8 patients at a mean of 49.0 +/- 15.4 months. The average range of motion in the anterior cruciate ligament-reconstructed knee was 6/0/133 at 1 month postoperatively and 6/0/145 at long-term follow-up. The mean manual maximum KT-1000 arthrometer difference between knees was 1.6 +/- 1.2 mm. The mean isokinetic quadriceps muscle strength of the reharvested graft donor knee was 103% +/- 7% of that of the opposite knee. Subjective scores were obtained from 11 patients (12 knees) at a mean of 51.5 +/- 35.7 months (range, 24 to 150) after surgery; the mean score was 89.3 +/- 6.9 points. We conclude that with appropriate preoperative planning, a reharvested patellar tendon can be used for revision anterior cruciate ligament reconstruction to obtain reliable stability and strength postoperatively.

Alterations of the extensor apparatus after anterior cruciate ligament reconstruction using the medial third of the patellar tendon

PURPOSE

The objective of this study was the ultrasound evaluation of the donor defect of the patellar tendon (PT) and the radiologic evaluation of the patella after harvesting of the medial third as a bone-patella tendon-bone (BPTB) graft for anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

This was a cohort study.

METHODS

In 45 patients who had ACL reconstruction, the extensor apparatus of the donor side was studied using ultrasound cross-sections and radiographs (anteroposterior, lateral, and a tangential view of the patella) 3 to 70 months postoperatively. Patients were divided into two groups. The early postoperative group (3 to 30 months postoperative) consisted of 27 patients (group A) and the late postoperative group (31 to 70 months postoperative) consisted of 18 patients (group B). The healthy contralateral extensor apparatus was used as control.

RESULTS

In group A, the standard ultrasound cross-section area of the PT increased by 20.48%, whereas in group B, it decreased by 4.88%. In group A, the patellar height was decreased by 9.21% in the donor side compared with the control. In group B, the patellar height was decreased by 7.02%. In group A, the Merchant's congruence angle increased by 11.59 degrees, and for group B, this angle increased by 3.82 degrees. This finding indicated that, after the 30th postoperative month, lateral displacement of the patella was not statistically significant (P =.38). In addition, no significant differences were found in the lateral patellofemoral angle in either group.

CONCLUSIONS

Our study indicates that the tendon defect is always healed and the final tendon cross-section area is 95% of the contralateral after the 30th postoperative month. In addition, there was a nonsignificant slight lateral displacement of the patella. In contrast, other studies found shown that there is a slight medial displacement of the PT after using the central third as a BPTB graft.

Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts

The authors review the current knowledge on donor site-related problems after using different types of autografts for anterior cruciate ligament (ACL) reconstruction and make recommendations on minimizing late donor-site problems. Postoperative donor-site morbidity and anterior knee pain following ACL surgery may result in substantial impairment for patients. The selection of graft, surgical technique, and rehabilitation program can affect the severity of pain that patients experience. The loss or disturbance of anterior sensitivity caused by intraoperative injury to the infrapatellar nerve(s) in conjunction with patellar tendon harvest is correlated with donor-site discomfort and an inability to kneel and knee-walk. The patellar tendon at the donor site has significant clinical, radiographic, and histologic abnormalities 2 years after harvest of its central third. Donor-site discomfort correlates poorly with radiographic and histologic findings after the use of patellar tendon autografts. The use of hamstring tendon autografts appears to cause less postoperative donor-site morbidity and anterior knee problems than the use of patellar tendon autografts. There also appears to be a regrowth of the hamstring tendons within 2 years of the harvesting procedure. There is little known about the effect on the donor site of harvesting fascia lata and quadriceps tendon autografts. Efforts should be made to spare the infrapatellar nerve(s) during ACL reconstruction using patellar tendon autografts. Reharvesting the patellar tendon cannot be recommended due to significant clinical, radiographic, and histologic abnormalities 2 years after harvesting its central third. It is important to regain full range of motion and strength after the use of any type of autograft to avoid future anterior knee problems. If randomized controlled trials show that the long-term laxity measurements following ACL reconstruction using hamstring tendon autografts are equal to those of patellar tendon autografts, we recommend the use of hamstring tendon autografts because there are fewer donor-site problems.

Revision anterior cruciate ligament reconstruction with a reharvested ipsilateral patellar tendon

The patellar tendon remains the most popular graft choice for anterior cruciate ligament reconstruction and has been proven to be the strongest substitute. Between 1991 and 1998, we performed revision anterior cruciate ligament reconstruction using the reharvested central third of the ipsilateral patellar tendon in 15 patients. Adequate follow-up was obtained in 13 of these 15 patients. The results in these 13 patients (mean age, 27.2 years) were reviewed. At an average postoperative follow-up of 39.4 months (range, 24 to 65), 11 patients had good or excellent results and 2 patients had fair results. Clinical examination revealed an average Tegner knee score of 5.8 (range, 3 to 9) and an average Lysholm knee score of 77.6 (range, 61 to 98). Postoperative KT-1000 arthrometer results showed an average side-to-side difference of 1.92 mm (range, -2.0 to 4.0). No patient demonstrated any loss of range of motion and only one reported patellofemoral problems, which were moderate. These favorable results demonstrate that, with appropriate patient selection, the use of a reharvested central third patellar tendon is a viable option for revision of a failed anterior cruciate ligament reconstruction.

Revision anterior cruciate surgery with use of bone-patellar tendon-bone autogenous grafts

BACKGROUND

A prospective study was done to determine the functional results, patient satisfaction, and graft failure rate after fifty-seven consecutive revision replacements of the anterior cruciate ligament with use of a bone-patellar tendon-bone autogenous graft.

METHODS

Fifty-four patients (fifty-five operations) were followed in this study. Concurrent operative procedures were performed during the revision procedure in thirty-seven knees (67%). These procedures included repair of a meniscal tear in twenty knees (36%) and reconstruction of deficient posterolateral or medial ligament structures in seventeen knees (31%). Nine knees (16%) had a high tibial osteotomy to correct varus malalignment before the revision operation. The results were evaluated with the Cincinnati Knee Rating System.

RESULTS

There were significant improvements in the scores for pain (p < 0.0001), activities of daily living (p < 0.01), sports participation (p < 0.001), patient satisfaction (p < 0.0001), and overall rating of the knee (p < 0.0001). Thirty-three (60%) of the replaced ligaments were functional, nine (16%) were partially functional, and thirteen (24%) had failed.

CONCLUSIONS

Many knees (93%) had compounding problems, including articular cartilage damage, prior meniscectomy, loss of secondary ligament restraints, varus malalignment, and concomitant ligament replacement or meniscal repair. Therefore, the results were generally less favorable than those following primary operations. The rate of graft failure was three times higher than our previously reported failure rate after primary replacements of the anterior cruciate ligament with a bone-patellar tendon-bone autogenous graft. Even so, symptoms and functional limitations with regard to daily and sports activities were found to have decreased and patient satisfaction improved. We advocate correction of varus malalignment prior to anterior cruciate procedures. Associated posterolateral ligament deficiencies should be surgically corrected during anterior cruciate procedures to prevent excessive loading on the graft from abnormal lateral tibiofemoral joint opening. Meniscal tears, including complex tears that extend into the avascular zone, can be concurrently repaired successfully during the revision.

Regeneration of the semitendinosus tendon harvested for anterior cruciate ligament reconstruction. Evaluation using ultrasonography

In a prospective study, 40 consecutive patients who underwent anterior cruciate ligament reconstruction with doubled semitendinosus and gracilis tendon autografts were examined pre- and postoperatively by ultrasound to investigate the anatomy of the donor site before and after the harvest of the tendons. The patients underwent ultrasonography at 2 weeks and 1, 2, 3, 6, 12, 18, and 24 months postoperatively. A total of 298 postoperative sonographic evaluations were performed. The semitendinosus tendon was imaged in the sagittal and axial planes: structure and margins were evaluated with the sagittal views; thickness and width were measured with the axial views. In all cases the following sequence of healing was documented: 2 weeks after surgery the semitendinosus tendon site was occupied by an area of increased thickness and decreased echogenicity, suggesting the presence of traumatic edema of the soft tissue surrounding the tenotomy. At 1 month, an irregular hypoechoic structure appeared in a near-anatomic position; at 2 months after surgery, thickness, width, and cross-sectional area of this structure were significantly greater than preoperatively. The amount of regenerated tissue increased up to that seen in the tissue of the 6-month examinations, which also showed a more uniform echostructure. The scans performed at 1 year showed distinct edges and reduction in thickness and width. At 18 and 24 months the echogenicity of the structure occupying the donor site was very similar to that of the normal semitendinosus tendon. However, this structure was clearly identified about 4 cm proximal to the pes anserinus, revealing a more proximal insertion of the regenerated semitendinosus tendon.

A radiographic and histologic evaluation of the patellar tendon after harvesting its central third

Nineteen consecutive patients undergoing anterior cruciate ligament reconstruction using the central third of the ipsilateral patellar tendon were included in the study. Serial magnetic resonance images revealed that the donor-site gap in the tendon decreased with time (mean follow-up, 26 months). The thickness was significantly increased compared with the intact contralateral patellar tendon, regardless of when the magnetic resonance imaging was performed. Ultrasonography showed the same findings at a mean follow-up of 26 months. Histologic evaluation of the repair tissue in the central part of the tendon, as well as the tissue in the peripheral part of the patellar tendon at the donor site, revealed a significant increase in cellularity and vascularity as compared with normal control tendons. Thus, 2 years after the harvesting procedure, the patellar tendon displayed significant radiographic and histologic abnormalities. On the basis of these findings, reharvest of the patellar tendon, at least up to 2 years after primary harvest, cannot be recommended.

Magnetic resonance imaging of the patellar tendon after harvesting its central third: a comparison between traditional and subcutaneous harvesting techniques

The aim of this study was to compare the 2-year results after anterior cruciate ligament reconstruction using patellar tendon autografts harvested through a paratenon-splitting, traditional technique (group A) with the results of a subcutaneous technique aiming at protecting the infrapatellar nerves and the paratenon (group B). Special emphasis was placed on evaluating the donor site. Magnetic resonance imaging (MRI) of the patellar tendon was performed to evaluate the reconstitution after harvesting its central third. Examinations of knee-walking ability and assessments of anterior knee sensitivity were made in order to evaluate donor-site discomfort and the function of infrapatellar nerves. Seventy-two consecutive patients were included in the study; group A comprised 35 patients and group B, 37 patients. At the 2-year follow-up, the Tegner activity level, the Lysholm score, and the IKDC evaluation system showed no significant differences between groups A and B. The median loss of normal anterior knee sensitivity was 16 cm2 (range, 0 to 200 cm2) in group A and 0 cm2 (range, 0 to 285 cm2) in group B (P = .20). In group A 20% of the patients and in group B 58% had normal sensitivity (P < .01). MRI showed that the donor-site gap (area corresponding to non-tendinous-like tissue signal) was 5 mm (range, 0 to 9 mm) in group A and 2 mm (range, 0 to 5 mm) in group B (P < .0001). At 2-year follow-up, the subcutaneous graft-harvesting technique resulted in less disturbance of anterior knee sensitivity and a smaller donor-site gap than the traditional technique.

A statistical analysis of the accuracy of sonography of the patellar tendon

The purpose of this study was to evaluate the accuracy of sonography in measuring the dimensions of the cadaveric patellar tendon to determine whether sonography might have future applications in the preoperative assessment of autograft tissues before anterior cruciate ligament (ACL) reconstruction. Eleven lower-extremity human cadaveric limbs, with an average donor age of 75 years (range, 67 to 87 years), underwent patellar sonography with a 7.5-MHz transducer. Patellar tendon thickness, width, and length were measured sonographically. After skin removal, the patellar tendon dimensions were measured manually. Sonographic and manual measurements were compared statistically. Sonographic and manual measurements showed good agreement for thickness. There was poor agreement for width and length. Because of its limited accuracy, sonography cannot be recommended for the measurement of the patellar tendon before ACL reconstruction.

Ipsi- or contralateral patellar tendon graft in anterior cruciate ligament revision surgery. A comparison of two methods

Twenty-four patients who underwent anterior cruciate ligament revision surgery were studied postoperatively (12 with reharvested ipsilateral patellar tendon grafts and 12 with contralateral patellar tendon grafts). For comparison purposes, 12 matched patients with primary anterior cruciate ligament reconstruction, who had been operated on using the same technique by the same surgeons, were chosen. The median time since the first reconstruction was 57 months (range, 15 to 132) in the ipsilateral tendon group and 54 months (range, 20 to 108) in the contralateral tendon group. Follow-up examination showed that there were no significant differences in total KT-1000 arthrometer side-to-side measurements between the groups, but the Lysholm score was higher for patients with contralateral tendon grafts than for patients with ipsilateral grafts. Only two patients with ipsilateral grafts were classified as having excellent or good results. Functional testing outcomes were similar for all groups, and magnetic resonance imaging screening showed no differences between the reharvest and primary harvest groups in terms of length, width, thickness, or donor site gap of the patellar tendon. However, there were two major complications in the group with revision surgery with the ipsilateral reharvested patellar tendon. Reharvesting the ipsilateral patellar tendon resulted in lower functional scores and a higher rate of complications than revision with the contralateral patellar tendon or primary anterior cruciate ligament reconstruction.

Positioning device for optimal active kinematic real-time magnetic resonance imaging of the knee joint: a technical note

OBJECTIVE: A prototype of a positioning device created especially for the diagnostic imaging of the patellofemoral joint was developed in order to achieve reproducible examination conditions. DESIGN: For this purpose a clinical trial on healthy test persons was carried out under real examination conditions. BACKGROUND: A special real-time MRI technique (Local-Look-technique) makes the analysis of active functional motion images possible. A prerequisite for this technique is accurate reproducible positioning of the knee joint in the MRI unit. METHODS: This positioning device was evaluated during a total of 50 examinations of the knee joints of five healthy test persons. The right patellofemoral joint of each test person was examined twice at different time points in order to check the reproducibility of all examination conditions. Comparing two examination series from the same individual, reproducibility of MRI slices was guaranteed by using identical anatomical landmarks. Image quality and test-retest reliability were analyzed on the computer screen. RESULTS: Optimal desired fixation of the leg in the MRI tube using the device was accomplished in all cases. The extent of motion of the knee joints ranged from 38 degrees (n = 2) to 40 degrees (n = 3) of flexion to full extension, which was satisfactory for the evaluation of the patellofemoral joint. Free movement of the patella and the lower leg was observed. The active functional MRI examination using this device was satisfactory and reproducible as assessed by test-retest reliability. CONCLUSIONS: The positioning device is a useful development in achieving active functional real-time MRI evaluation of the knee and patellofemoral joint. Using this diagnostic tool, reproducible quantitative examinations can now be easily performed. The reproducibility and high reliability as well as its simplicity of operation render this diagnostic tool suitable for use in orthopedics and traumatology.

Postoperative patellar tendon healing: an ultrasound study. VIS Tendon Study Group

The patellar tendon donor site of 20 patients who underwent anterior cruciate ligament (ACL) reconstruction using the patellar tendon tissue as autograft was examined with high resolution 7.5 MHz ultrasound. The patients were randomly divided into four groups and studied at 3, 6, 9 or 12 months postoperatively. The size of the postoperative tendon defect was measured just distal to the lower pole of the patella. The size of the tendon defect diminished progressively from a mean of 109 mm2 at 3 months to a mean of 23 mm2 at 12 months. Increasing echogenicity was first noticed 12 months after tendon repair. Seven patients developed clinical features postoperatively of jumper's knee (patellar tendinosis). There were no ultrasound signs that differentiated these patients from asymptomatic patients. It is concluded that ultrasound provides objective evidence of patellar tendon healing after ACL reconstruction: the surgical defect diminished in size and became echogenic after a period of 12 months.

Histological and biomechanical observations of the rabbit patellar tendon after removal of its central one-third

Using 35 Japanese white rabbits, a study was made of tissue regeneration and the mechanical properties of the patellar tendon after removal of its central one-third. After removal of the central one-third of the patellar tendon on one side, in experiment 1 the strength of the entire patellar tendon including the regenerated tissue was compared with that of the patellar tendon on the opposite side with the central one-third removed at the time of killing, and in experiment 2 the strength of only the regenerated tissue was compared with that of the patellar tendon on the opposite side with two-thirds of the medial and lateral sides removed at the time of death. In experiment 1, the maximum load showed no significant difference between the operated side and the control. In one half of the cases, the strength of the operated side including the regenerated tissue was weak, suggesting weakening of the patellar tendon on the residual bilateral sides. In experiment 2, the maximum load of the regenerated tissue was significantly lower than that of the control, the former being 25% of the latter even at 6 months. Histologically, the characteristics of the cells and collagen fibers gradually approached those of normal tissue, but the crimp pattern of the collagen fibers and fibrils was evidently smaller than that of the control. These results indicate that regenerated tissue was still mechanically weak and immature at 6 months.

The reharvested central third of the patellar tendon. A histologic and biomechanical analysis

We assessed the histologic, mechanical, and structural properties of the reharvested central-third patellar tendon in greyhounds. Twelve dogs had the central third of the patellar tendon (5 mm) removed with corresponding bone blocks from the patella and tibia; the remaining tendon defect was loosely closed. Six dogs were sacrificed at 6 months and six at 12 months, and the central third of the patellar tendon was harvested from both the operative and the contralateral control knees. Analysis of the structural changes in the tendons revealed a significant increase in thickness for reharvested tendons at both 6 and 12 months when compared with controls. The entire residual tendons were narrower at 6 months and were shorter at 12 months compared with controls. Mechanical testing showed that the average failure load, ultimate tensile strength, strain at failure, and average modulus for the reharvested central third of the patellar tendon were significantly less than that of controls at both 6 and 12 months. Analysis of collagen fiber size by electron microscopy revealed a significant increase in collagen fiber diameter at 6 months (135 +/- 41 nm versus 49 +/- 4 nm) but no difference between the operative limbs and controls at 12 months. The reharvested bone-patellar tendon-bone complex does not have the same properties as the primary patellar tendon graft up to 1 year after harvest in a canine model, and its use for revision cruciate ligament reconstruction must be carefully reexamined.

Characterization of the repair tissue after removal of the central one-third of the patellar ligament. An experimental study in a goat model

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.

Revision anterior cruciate ligament surgery: experience from Cincinnati

Prospective studies were done to determine the outcome of allografts and autografts used for revision anterior cruciate ligament reconstruction. The allograft group was comprised of 65 patients observed for a mean of 42 months postoperatively; the autograft (bone-patellar ligament-bone) group contained 20 patients observed for a mean of 27 months postoperatively. KT-2000 testing and a comprehensive knee examination were done on all the patients. The Cincinnati Knee Rating System was used for assessment. Significant improvements were noted in all patients for symptoms, functional limitations, anteroposterior displacements, pivot shift tests, and overall rating scores. KT-2000 results showed 53% of the allograft group and 67% of the autograft group had less than 3 mm increased displacement (not statistically significant). The overall failure rates were 33% for the allografts and 27% for the autografts. Preoperative planning and technical aspects of anterior cruciate ligament revision procedures are described. The authors prefer bone-patellar ligament-bone autografts for anterior cruciate ligament revision, although the data presented were considered preliminary. Bone-patellar ligament-bone allografts may be used when autogenous tissues are not available, because they offer reasonable success rates for patients who are symptomatic with daily activities.

Revision of failed prosthetic anterior cruciate ligament reconstruction

Revision of failed prosthetic anterior cruciate ligament reconstructions will continue to be necessary as previously placed prosthetic devices fail with time. These patients often present with recurrent instability, pain, swelling, or effusions. Graft rupture and the generation of particulate debris are common causes of these symptoms. To effectively treat these patients requires careful preoperative evaluation and planning. Operative treatment includes removing the prosthesis and metal fixation devices, evaluating femoral and tibial bone stock, and determining adequacy of previous tunnel position. Staging of the operation may be a necessity if significant bone loss or poor tunnel position on either the femoral or tibial side requires bone grafting. The use of an autogenous bone-patellar tendon-bone graft is suggested and has proven to be effective in restoring knee stability in these revision cases. The ultimate outcome following revision of failed prosthetic ligaments may be limited by associated intraarticular pathology often seen in this patient population.

MRI of anterior cruciate ligament healing

OBJECTIVE

The purpose of this study was to evaluate using MRI the natural healing of the anterior cruciate ligament (ACL) when treated conservatively by early protective motion.

MATERIALS AND METHODS

Consecutive acute complete intraligamentous ruptures of the ACL in 50 cases that were allowed to heal without surgery were evaluated before and after 3 month treatment by MRI, arthroscopy, and stress radiographs. Twenty-nine of the 50 patients were also reevaluated 11 months from the initial injury, of which 7 were reevaluated again 24 months from the initial injury by MRI. The MR appearance of the treated ACL was categorized into four grades depending on homogeneity, straight band, and size.

RESULTS

MR assessment of the ACL after 3 month treatment demonstrated a well defined normal-sized straight band in 37 cases (74%). There was a significant relationship between the 3 and 11 month MR evaluations (rs = 0.801, p <0.0001). There were also significant relationships between the MR and arthroscopic evaluations (rs = 0.455, p <0.005) and between the MR stress radiographic evaluations (rs = 0.348, p <0.025) after the 3 month treatment.

CONCLUSION

MRI can demonstrate ACL healing when treated conservatively with early protective mobilization.