Autologous bone marrow stromal cell transplantation for repair of full-thickness articular cartilage defects in human patellae: two case reports

This study assessed the effectiveness of autologous bone marrow stromal cell transplantation for the repair of full-thickness articular cartilage defects in the patellae of a 26-year-old female and a 44-year-old male. These two patients presented in our clinic because their knee pain prevented them from walking normally. After thorough examination, we concluded that the knee pain was due to the injured articular cartilage and decided to repair the defect with bone marrow stromal cell transplantation. Three weeks before transplantation, bone marrow was aspirated from the iliac crest of each patient. After erythrocytes had been removed by use of dextran, the remaining nucleated cells were placed in culture. When the attached cells reached subconfluence, they were passaged to expand in culture. Adherent cells were subsequently collected, embedded in a collagen gel, transplanted into the articular cartilage defect in the patellae, and covered with autologous periosteum. Six months after transplantation, clinical symptoms (pain and walking ability) had improved significantly and the improvement has remained in effect (5 years and 9 months posttransplantation in one case, and 4 years in the other), and both patients have been satisfied with the outcome. As early as 2 months after transplantation, the defects were covered with tissue that showed slight metachromatic staining. Two years after the first and 1 year after the second transplantation, arthroscopy was performed and the defects were repaired with fibrocartilage. Results indicate autologous bone marrow stromal cell transplantation is an effective approach in promoting the repair of articular cartilage defects.

Safety of autologous bone marrow-derived mesenchymal stem cell transplantation for cartilage repair in 41 patients with 45 joints followed for up to 11 years and 5 months

Among autologous somatic stem cells, bone marrow-derived mesenchymal stem cells (BMSCs) are the most widely used worldwide to repair not only mesenchymal tissues (bone, cartilage) but also many other kinds of tissues, including heart, skin, and liver. Autologous BMSCs are thought to be safe because of the absence of immunological reaction and disease transmission. However, it is possible that they will form tumours during long-term follow-up. In 1988, we transplanted autologous BMSCs to repair articular cartilage, which was the first such trial ever reported. Subsequently we performed this procedure in about 40 patients. Demonstration that neither partial infections nor tumours appeared in these patients provided strong evidence for the safety of autologous BMSC transplantation. Thus, in this study we checked these patients for tumour development and infections. Between January 1998 and November 2008, 41 patients received 45 transplantations. We checked their records until their last visit. We telephoned or mailed the patients who had not visited the clinics recently to establish whether there were any abnormalities in the operated joints. Neither tumours nor infections were observed between 5 and 137 (mean 75) months of follow-up. Autologous BMSC transplantation is a safe procedure and will be widely used around the world.

Single- versus bi-socket anterior cruciate ligament reconstruction using autogenous multiple-stranded hamstring tendons with endoButton femoral fixation: A prospective study

PURPOSE

This prospective study was conducted to compare the single-socket and the bi-socket anterior cruciate ligament (ACL) reconstruction techniques in terms of outcome.

TYPE OF STUDY

Nonrandomized control trial.

METHODS

There were 160 consecutive patients with unilateral chronic ACL insufficiency who underwent endoscopic single- or bi-socket ACL reconstruction alternately using multiple-stranded medial hamstring tendon and EndoButton (Smith & Nephew, Andover, MD) femoral fixation. All patients underwent the same postoperative rehabilitation protocol. Of them, 106 patients (57 single, 49 bi) were available for 2-year follow-up.

RESULTS

According to the IKDC Knee Ligament Evaluation Form, 23 patients (40%) of the single-socket group were subjectively graded as normal, 30 (53%) as nearly normal, and 4 (7%) as abnormal. Twenty-six patients (53%) of the bi-socket group were graded as normal, 21 (43%) as nearly normal, and 2 (4%) as abnormal (P =.19). The mean side-to-side anterior laxity difference (KT-1000 manual maximum force) was 0.9 +/- 1.8 mm for the single-socket group and 0.7 +/- 1.2 mm for the bi-socket group (P =.44). Fifty-three of 57 patients (93%) in the single-socket group and all patients in the bi-socket group showed anterior laxity differences of +/-3 mm or less (P =.12). There were no differences in thigh muscle strength between the groups.

CONCLUSIONS

Both single- and bi-socket ACL reconstruction using autogenous multiple-stranded hamstring tendons with EndoButton fixation provided satisfactory anterior stability, and there were no statistically significant differences in subjective results or measured restored stability between the 2 groups.

Anterior cruciate ligament reconstruction with multistranded autogenous semitendinosus tendon

We evaluated 41 knees 24 to 48 months after anterior cruciate ligament reconstruction was performed using multiple autogenous semitendinosus tendons. The ipsilateral free semitendinosus tendon was tripled or quadrupled to make a graft 7 to 10 mm in diameter and more than 60 mm long. When the diameter of the graft was less than 7 mm, an ipsilateral doubled gracilis tendon was also used (in seven cases). Twenty-three patients (56%) returned to their preinjury activity levels. According to the patients' subjective assessment, 34 (83%) graded themselves as normal or nearly normal. No patient reported giving way of the knee or limitation of knee motion. The average anterior laxity difference between the involved knee and contralateral uninjured knee was 1.5 mm at 200 N. Twenty-nine patients (71%) demonstrated an anterior laxity difference of 3 mm or less when the involved knee was compared with the contralateral uninjured knee. Quadriceps muscle strength was 90% compared with the contralateral healthy limb, and hamstring muscle strength was equivalent to the contralateral limb. In our study, tripled or quadrupled semitendinosus free tendons were excellent anterior cruciate ligament grafts for restoring knee stability, recovering thigh muscle power, and preserving knee motion.

Evaluation of active knee flexion and hamstring strength after anterior cruciate ligament reconstruction using hamstring tendons

PURPOSE

The purpose of this study was to evaluate active knee flexion range of motion and hamstring strength following hamstring anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

Case control study, consecutive sample.

METHODS

Seventy-four consecutive patients who had undergone hamstring ACL reconstruction underwent isokinetic muscle strength testing at 2 years post surgery. Measurements of the maximum standing active knee flexion angle with the hip extended were also taken. During isokinetic testing, we evaluated flexion torque at 90 degrees of knee flexion, in addition to the peak flexion torque. We further compared these parameters of muscle strength around the knee for the patients in whom only semitendinosus tendon was harvested as a graft source (ST group), and those from whom the semitendinosus tendon and the gracilis tendon were harvested (ST/G group).

RESULTS

Isokinetic testing showed that, in both the ST and ST/G groups, the knee flexor strength of the involved leg was less effectively restored at 90 degrees of knee flexion than at the angle at which the peak torque was generated. Conversely, no significant difference was seen in the side-to-side ratio in either the peak flexion torque or the 90 degrees flexion torque between the groups. The side-to-side ratio in mean maximum standing knee flexion angle was significantly lower in the ST/G group than in the ST group.

CONCLUSIONS

This study suggests that the loss of knee flexor strength following the harvest of the hamstring tendons may be more significant than has been previously estimated. Furthermore, multiple tendon harvest may affect the range of active knee flexion.

Early biological effect of in vivo gene transfer of platelet-derived growth factor (PDGF)-B into healing patellar ligament

To define the early biological effect of in vivo introduction of the PDGF-B gene on the healing of ligaments, a HVJ-liposome suspension containing platelet-derived growth factor (PDGF)-B cDNA was injected directly into the injured patellar ligament of 14-week-old male Wistar rats. Rats were killed at 1, 4 and 8 weeks for the morphological analysis of angiogenesis by laminin immunohistochemistry and of collagen deposition by Masson's Trichrome staining and collagen I immunohistochemistry. PDGF-B gene transfer caused the enhanced expression of PDGF in healing ligament up to 4 weeks after transfection, leading to an initial promotion of angiogenesis and subsequent enhanced collagen deposition in the wound. Enhanced and accelerated matrix synthesis in the PDGF-B gene introduced healing ligament suggests that this gene transfer technique may be a potentially useful tool for improving soft tissue repair.

Maturation of allograft tendons transplanted into the knee. An arthroscopic and histological study

We have performed an arthroscopic and histological study of the remodelling process of allogeneic tendons transplanted into the human knee as anterior cruciate ligament substitutes. Arthroscopic observations from six weeks to 55 months after operation showed that the grafts were viable, and that early surface hypervascularity subsided with time; moreover, these appearances remained unchanged from 11 months postoperatively onwards. Histological studies from three to 55 months after operation showed that all the grafts were infiltrated with fibroblasts, and that cellularity in their substance reduced with time, remaining unchanged from 18 months onwards; the collagen bundles were aligned as in a normal ligament from six months onwards. These findings suggest that the grafts reach maturity within the first 18 months and remain unchanged as viable ligaments thereafter.

Factors Affecting the Outcomes of Double-Bundle Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocations Evaluated by Multivariate Analysis

BACKGROUND

Many factors are involved in causing patellar instability or recurrent patellar dislocations. However, factors affecting the outcomes of anatomic medial patellofemoral ligament (MPFL) reconstruction have not been fully documented.

PURPOSE

To evaluate the rate of recurrent patellar instability after isolated MPFL reconstruction and to elucidate factors affecting the outcomes of isolated MPFL reconstruction using multivariable statistics.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 42 patients (44 knees) who underwent isolated, anatomic MPFL reconstruction using a semitendinosus autograft without any additional patellar stabilization procedures for treating recurrent patellar dislocations were included in this study. All patients were followed for more than 2 years; the mean follow-up period was 3.2 years (range, 2-9 years). Postoperative patellofemoral instability was diagnosed when the patient complained of recurrent patellar subluxations or dislocations or had a positive apprehension sign during follow-up. Preoperative radiographic findings were obtained using plain radiography and computed tomography. Femoral tunnel positions were assessed on postoperative radiographs. The strength of the relationship between postoperative patellofemoral instability and potential risk factors such as preoperative age, sex, body mass index, patellar type, sulcus angle, congruence angle, lateral tilt angle, patellar height, tibial tubercle-trochlear groove (TT-TG) distance, degree of trochlear dysplasia, and femoral bone tunnel position were evaluated by univariate and multivariate logistic regression analyses.

RESULTS

At follow-up, 2 knees had experienced a redislocation (4.5%). A positive apprehension sign was still evident in 8 knees (18.2%). Three factors, including the sulcus angle, the congruence angle, and trochlear dysplasia, were extracted by single linear regression analysis. Univariate logistic regression analysis showed that the sulcus angle (odds ratio [OR], 1.11; 95% CI, 1.01-1.22; P = .04) and trochlear dysplasia (OR, 3.04; 95% CI, 1.39-6.63; P = .01) were associated with postoperative patellofemoral instability. Trochlear dysplasia was independently associated with postoperative patellofemoral instability by multivariable logistic regression analysis (P < .05). An increased TT-TG distance exerted a significant effect on the outcomes of MPFL reconstruction, particularly in patients with type D trochlea.

CONCLUSION

Severe trochlear dysplasia is the most important predictor of residual patellofemoral instability after isolated MPFL reconstruction. In addition, an increased TT-TG distance affected the outcomes in patients with type D trochlea. Additional patellar stabilization procedures should be considered for patients with severe trochlear dysplasia and an increased TT-TG distance.

Deterioration of patellofemoral articular surfaces after anterior cruciate ligament reconstruction

One hundred eighty-seven patients who had undergone intraarticular anterior cruciate ligament reconstruction using either a fresh-frozen allogeneic tendon or central third autogenous pateller tendon 3 to 89 months previously were arthroscopically evaluated. The focus was on secondary changes of the patellofemoral joint at the time of second-look arthroscopy. Overall, 93 knees deteriorated, 74 knees remained unchanged, and 14 improved. The deteriorative changes were predominantly located around the central ridge of the patellae, although all but two knees remained free from anterior knee pain. Statistical multivariate analysis showed surgical approach by conventional medial parapatellar incision and use of the central one-third of the autogenous patellar tendon graft as possible risk factors for the deterioration, although chi-square analysis failed to demonstrate statistical significance for the latter.

Reconstruction of the anterior cruciate ligament using allogeneic tendon. Long-term followup

Eighty-four patients who underwent ACL reconstruction with fresh-frozen allogeneic tendon were reviewed and evaluated with subjective and functional rating scales, physical examinations, instrumented anterior drawer tests, isokinetic testing, and arthroscopy. The average followup was 57 months (range, 36 to 90 months) and the average age at operation was 22 years (range, 16 to 37 years). The subjective and functional results were rated as excellent in 48 patients (57%), good in 31 (37%), and fair in 2 (2%). Three patients (3%) experienced a retear of the ACL. Physical examinations and instrumented anterior drawer tests showed that satisfactory anterior stability was restored in 88% of the patients. Isokinetic evaluations demonstrated that the extension torque of the involved knee recovered to a slightly lower level than that of the controls, although the flexion torque recovered to a level equivalent to that of the controls. Arthroscopic evaluations revealed that the allografts were elaborately remodeled, viable, and taut. There was no sign of immunologic rejection at any time postoperatively. Additional extraarticular procedures, consisting of both pes anserinus transfer on the medial side and iliotibial band reinforcement on the lateral side, had no effect on the results.

The effects of knee motion and external loading on the length of the anterior cruciate ligament (ACL): a kinematic study

A six-degrees-of-freedom mechanical linkage device was designed and used to study the unconstrained motion of ten intact human cadaver knees. The knees were subjected to externally applied varus and valgus (V-V) moments up to 14 N-m as well as anterior and posterior (A-P) loads up to 100 N. Tests were done at four knee flexion angles; 0, 30, 45, and 90 deg. Significant coupled axial tibial rotation was found, up to 21.0 deg for V-V loading (at 90 deg of flexion) and 14.2 deg for A-P loading (at 45 deg of flexion). Subsequently, the knees were dissected and the locations of the insertion sites to the femur and tibia for the anteromedial (AM), posterolateral (PL), and intermediate (IM) portions of the ACL were identified. The distances between the insertion sites for all external loading conditions were calculated. In the case when the external load was zero, the AM portion of the ACL lengthened with knee flexion, while the PL portion shortened and the intermediate (IM) portion did not change in length. With the application of 14 N-m valgus moment, the PL and IM portions of the ACL lengthened significantly more than the AM portion (p less than 0.001). With the application of 100 N anterior load, the AM portion lengthened slightly less than the PL portion, which lengthened slightly less than the IM portion (p less than 0.005). In general, the amount of lengthening of the three portions of the ACL during valgus and anterior loading was observed to increase with knee flexion angle (p less than 0.001).

Evaluation of a new injury model to study medial collateral ligament healing: primary repair versus nonoperative treatment

The medial collateral ligament (MCL) of the rabbit left hindlimb was ruptured by a rod placed beneath it, resulting in a "mop-end" tear of the ligament substance with simultaneous injury to the insertion sites. Using this model, we compared primary ligament repair and nonoperative treatment using biomechanical and histologic techniques at time zero, 10 days, and 6 and 12 weeks postoperatively. Biomechanical evaluation included measurement of varus-valgus (V-V) knee rotation, in situ load on the MCL, and tensile testing of the femur-MCL-tibia complex (FMTC). The V-V rotation of all experimental knees decreased over time. At 12 weeks, V-V rotation of experimental knees was still 1.3 times larger than that of controls. Primary repair initially decreased V-V rotation, but at 6 and 12 weeks there was no statistical difference between operated and nonoperated knees. The in situ load on the MCL followed the same trends. There was no significant effect of MCL repair on any of the tensile properties. However, postoperative healing time significantly improved the FMTC structural properties in both experimental groups. Failure modes of the FMTCs and histologic sections of the ligament insertion sites indicated that after injury the ligament insertion to bone recovered more slowly than the ligament substance. Tensile testing of the FMTC showed that even at 12 weeks postoperatively the mechanical properties of the healed ligament material remained significantly different from those of the controls.

Quantitative evaluation after arthroscopic anterior cruciate ligament reconstruction. Allograft versus autograft

We measured the anteroposterior ligamentous laxity and thigh muscle power in 92 subjects who were rated as successes after they had undergone arthroscopic anterior cruciate ligament reconstruction for unilateral anterior cruciate ligament insufficiency 18 to 36 months previously. The subjects were divided into 2 groups according to the type of graft: fresh-frozen allogenic tendon (N = 47) or central one third of the ipsilateral patellar tendon (N = 45). Instrumented drawer tests in the Lachman position were performed to measure anterior tibial displacement at 200 N (anterior laxity). Thigh muscle power was isokinetically measured with a Cybex II dynamometer. Significantly more anterior laxity was found in the reconstructed knees than in the contralateral normal knees regardless of graft material (paired t-test, P < 0.01), except for the male allograft patients. Although the mean anterior laxity difference between sides for the allograft patients was less than that for the autogenous ones, analysis of variance failed to demonstrate a statistically significant difference between the 2 groups if the comparison was strictly made within the same sex. Thigh muscle tests revealed that extension torque in the reconstructed knees was significantly less than that in the contralateral knees and analysis of variance showed that knee extension torque at 60 deg/sec for the allograft patients was significantly better than that of the autograft ones (P < 0.05). We concluded that the allograft procedure is advantageous over the patellar tendon autograft in terms of better restoration of anterior stability.

Second-look arthroscopy after meniscal repair. Review of 132 menisci repaired by an arthroscopic inside-out technique

From 1986 to 1993, we repaired 278 torn menisci in 264 patients using an arthroscopically assisted inside-out technique. A total of 132 meniscal repairs in 122 patients were evaluated by second-look arthroscopy. At review, only nine patients had meniscal symptoms, such as locking, swelling or pain. Ninety-seven menisci (73%) had healed completely at the repair site, but there were new tears in different areas of 21 menisci, some of which had complete healing at the repair site. Incomplete healing, seen in 23 menisci (17%), was frequently near the popliteus tendon, most commonly where there had been an associated anterior-cruciate-ligament injury. Arthroscopically-assisted meniscal repair seems to be a reliable procedure, but some clinically successful cases had incomplete healing at the repair site or a newly-formed tear in the meniscal body or both. These lesions may cause meniscal symptoms to appear at a later date.

Conservative treatment of isolated injuries to the posterior cruciate ligament in athletes

We assessed arthroscopically 22 young athletes with an isolated acute posterior cruciate ligament (PCL) injury. Four had significant damage to the articular cartilage of the medial femorotibial compartment and were advised not to resume sports. Three underwent PCL reconstruction because of a reparable meniscal tear or instability. The other 15 were treated conservatively and resumed sport. At an average follow-up of 51 months, one had developed arthritic symptoms due to newly-developed severe chondral damage to the medial femoral condyle, but none of the other 14 had developed arthritic symptoms and most remained athletically active. Severe chondral damage should be seen at an early arthroscopy. Knees with an isolated injury to the PCL with concomitant articular damage may be successfully managed by conservative treatment.

The effects of frequency and duration of controlled passive mobilization on tendon healing

This study was designed to determine the effects of frequency and duration of controlled passive motion on the healing flexor tendon following primary repair. Adult mongrel dogs were divided into two groups based on frequency of controlled passive motion. In one group, motion was applied manually at a frequency of 12 cycles/min for 5 min/day; in the other group, a continuous passive motion machine was used to apply motion at a lower frequency of 1 cycle/min for 60 min/day, making the number of cycles each day for both groups identical. Gliding function and tensile properties of repaired tendons were evaluated biomechanically at 3 and 6 weeks postoperatively. Results showed that gliding function in both groups was similar, but tensile properties, as represented by linear slope, ultimate load, and energy absorption, were significantly improved in the higher frequency group. It was concluded that frequency of controlled passive motion rehabilitation is a significant factor in accelerating the healing response following tendon repair, and higher frequency-controlled passive motion has a beneficial effect.

Cross-sectional area measurement of the semitendinosus tendon for anterior cruciate ligament reconstruction

We measured the cross-sectional area (CSA) of the semitendinosus tendon (SMT) in 79 anterior cruciate ligament (ACL)-injured patients using magnetic resonance imaging (MRI) to scrutinize their appropriateness for ACL grafts. Measurements of the CSAs of the SMT with MRI were closely correlated with intraoperative direct measurement (y = 0.697). The mean CSAs of the SMT measured with MRI ranged from 6.3 to 15.0 mm2 with a mean of 10.1+/-2.1 mm2. The CSA of the SMT measured with MRI proved to be a useful indicator to determine preoperatively whether the SMT graft would be of adequate dimensions (7 mm or more in diameter, 60 mm or more in length) for ACL reconstruction. If the CSA of the SMT was more than 11 mm2, a sufficiently thick and long graft could be prepared with a tripled or quadrupled SMT in 89% of cases. We conclude that tissue CSA measurements using MRI could potentially be implemented as a useful tool for determining the most appropriate donor autograft tissue preoperatively, thus minimizing harvest-site morbidity.

Age-related changes in the knee meniscus

BACKGROUND

Aging is the most prominent risk factor for the development of osteoarthritis (OA), which affects knees and causes major health burdens. Meniscal dysfunction mostly based on degeneration contributes to the development and progression of knee OA. Meniscal degeneration is caused by various extrinsic factors, such as repetitive trauma or leg malalignment, while meniscal aging is considered as internal changes, such as molecular or cellular changes. Little is known about age-related changes in the meniscus. Therefore, this review aimed to summarize and clarify the understanding of the aged meniscus.

METHODS

There are few articles about natural aging in the meniscus, because most reports only demonstrate the effects of OA on the meniscus. We searched PubMed (1948 to November 2016) to identify and summarize all English-language articles evaluating natural aging in the meniscus.

RESULTS

There is evidence of compositional change in the meniscus with aging, involving cells, collagens, and proteoglycans. In addition, as recent reports on the natural aging of cartilage have indicated, senescence of the meniscal cells may also lead to disruption of meniscal cells and tissue homeostasis. Due to the low turnover rate of collagen, accumulation of advanced glycation end-products largely contributes to tissue stiffness and vulnerability, and finally results in degenerative changes or tears. Furthermore, environmental factors such as joint fluid secreted by inflamed synovium could also contribute to meniscal tissue deterioration.

CONCLUSIONS

Age-related changes induce meniscal tissue vulnerability and finally lead to meniscal dysfunction.

Influences of flexor sheath continuity and early motion on tendon healing in dogs

The healing response of flexor tendons treated with either sheath reconstruction or sheath excision, and early passive motion rehabilitation was investigated in a canine model. Flexor sheath repair, sheath excision, and autogenous sheath grafting were compared for biomechanical characteristics, and biochemical and ultrastructural alterations at the repair site at intervals over a 12-week period. No significant differences could be found in tendons treated with either sheath repair or sheath excision by biomechanical, biochemical, or morphologic assessments. Although ultimate load and linear slope values increased significantly in both groups at each interval (p less than 0.05 for each comparison), there were no significant differences in angular rotation of the distal interphalangeal joint over time. Biochemical findings showed high levels of reducible Schiffbase crosslinks through 12 weeks, indicating a repair process undergoing active remodeling. Ultrastructural studies showed active fibrinogenesis and early evidence of longitudinal alignment of collagen fibrils in the extracellular matrix. In the sheath graft group, strength characteristics did not increase over time, and there was a high degree of disorganization of collagen fibril orientation. These findings demonstrate that reconstruction of the tendon sheath, either by suture or autogenous graft, does not improve significantly the biomechanical, biochemical, or morphologic characteristics of repaired tendons treated with early motion rehabilitation.

Results of isolated meniscal repair evaluated by second-look arthroscopy

Thirty-six isolated torn menisci in 35 patients (average age, 24 years) which had been repaired arthroscopically using an inside-out technique were evaluated by second-look arthroscopy. The time from meniscal repair to second-look arthroscopy ranged from 2 to 10 months with a mean of 5 months. The indications for meniscal repair were a longitudinal or oblique tear located at the outer half of the meniscus. Twenty (56%) were graded as excellent, 10 (28%) as good, and 6 (16%) were graded as poor. Neither age nor length of time between injury and repair affected meniscal healing. The medial meniscal repairs showed better results than the lateral repairs (rate of excellent results: medial, 82%; lateral, 44%; P < .01, chi-squared test). The rate of excellent results for those with normal meniscal bodies at the time of repair was 79%, which was significantly higher than that seen in the cases with deformed and/or superficial damage to the meniscal body (36%; P < .05, chi-squared test).

Collagen fibril populations in human anterior cruciate ligament allografts. Electron microscopic analysis

We studied human anterior cruciate ligament allograft specimens by quantitative electron microscopy to analyze their collagen fibril populations. The specimens were procured at the time of second-look arthroscopy from the superficial region of the midzone of the anterior cruciate ligament grafts after synovial clearage. The grafts used for the anterior cruciate ligament reconstructions were from fresh-frozen allogenic Achilles, tibialis anterior or posterior, or peroneus longus or brevis tendons and had been implanted 3 to 96 months previously. By 12 months after surgery, the anterior cruciate ligament allografts consisted predominantly of small-diameter collagen fibrils (30 to 80 nm), which resulted in a unimodal pattern in the collagen fibril profile. The number of large-diameter fibrils (90 to 140 nm) within the allogenic tendon grafts had decreased. This predominance of small-diameter collagen fibrils persisted in almost all specimens older than 12 months. The anterior cruciate ligament allografts had collagen fibril profiles that did not resemble normal tendon grafts or normal anterior cruciate ligaments, even several years after surgery.

Second-look arthroscopy of anterior cruciate ligament grafts with multistranded hamstring tendons

PURPOSE

The purpose of this study was to clarify the fate of intra-articularly transplanted multistranded hamstring tendon grafts used for anterior cruciate ligament (ACL) reconstruction.

TYPE OF STUDY

Consecutive samples.

METHODS

The subjects were 153 patients (156 knees) with a mean age of 24 years, who had been evaluated as experiencing clinical success. The patients consented to undergo second-look arthroscopy after ACL reconstruction with multistranded autogenous hamstring tendon grafts at 5 to 51 months previously. Ninety-six knees were surgically treated with the single-socket procedure, and the remaining 60 were treated with the bisocket procedure. None of the patients complained of instability of the index knee. The mean side-to-side difference at manual-maximum force in anterior displacement by KT-1000 on 107 patients was 1.2 +/- 1.1 mm (-1 to 4 mm). Arthroscopic evaluation was performed focusing on tension and thickness dividing into 3 groups based on the postoperative period. The chi-square and Mann-Whitney U tests were used for statistical analysis.

RESULTS

A total of 139 grafts (89%) were evaluated as taut and 17 (11%) as mildly lax or lax. Fifty-three (34%) showed some partial tear, and the other 103 (66%) appeared thick without partial tear. The percentage of mildly lax or lax grafts in the group of patients older than 2 years was higher than that in patients younger than 1 year, and no significant difference was found among the groups in the percentage of partially torn grafts. The patients with mildly lax or lax grafts showed statistically higher KT values, while those with partially torn grafts did not. No statistically significant difference was seen in any of these findings between the 2 procedures, although the bisocket procedure tended to show better tension or thickness.

CONCLUSIONS

Arthroscopically, 11% of the hamstring ACL grafts showed looseness and 34% had partial tear in the clinically successful knees.

LEVEL OF EVIDENCE

Level IV in therapeutic studies investigating the results of treatment.

Measurement of anterior instability of the knee. A new apparatus for clinical testing

We have developed an apparatus to measure the anteroposterior stability of the knee to forces of up to 250 N, applied at 20 degrees of flexion. We measured anterior laxity at 200 N, anterior stiffness at 50 N and total laxity at +/- 200 N. A study of cadaveric knees revealed that the soft tissues surrounding the bones had a significant influence on the force-displacement curve, and emphasised that differences between injured and normal pairs of knees are much more important than the absolute values of the parameters. In 61 normal volunteers we found no significant left to right differences in anterior laxity at 200 N and anterior stiffness at 50 N. In 92 patients with unilateral anterior cruciate deficiency there were significant differences (p less than 0.0005) in anterior laxity, anterior stiffness and total laxity, the injured-normal differences averaging 6.7 mm, 1.3 N/mm, and 8.1 mm respectively.