The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs.

Recent in vitro research suggests that ACL reconstruction does not restore tibial rotation. This study investigated rotational knee joint stability in vivo during a combined descending and pivoting movement that applies a high rotational load to the knee joint. We studied 20 ACL reconstructed patients (bone-patellar tendon-bone graft) and 15 matched controls with a six-camera optoelectronic system performing the examined movement. In the control group the results showed no significant differences in the amount of tibial rotation between the two sides. No significant differences were also found between the contralateral intact leg of the ACL group and the healthy control. However, a significant difference was found within the ACL reconstructed group and between the reconstructed and the contralateral intact leg. Therefore ACL reconstruction may not restore tibial rotation even though anterior tibial translation has been reestablished.

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.

A multidisciplinary study of the healing of an intraarticular anterior cruciate ligament graft in a goat model.

We evaluated knee function, tensile properties, and histologic appearance of a healing intraarticular bone-patellar tendon-bone autograft after anterior cruciate ligament reconstruction in a goat model. The patellar tendon graft was fixed such that both bone-to-bone (femoral tunnel) and bone-to-tendon (tibial tunnel) healing could be studied. The total anteroposterior translation significantly increased from 3 to 6 weeks, ranging from increases of 28.8% to 46.7%. In situ forces in the replacement graft decreased as much as 22.2% at 6 weeks. Conversely, tensile properties of the femur-anterior cruciate ligament graft-tibia complex did not change significantly from 3 to 6 weeks. However, the mode of failure changed from the graft pulling out of the tibial tunnel at 3 weeks to a mix of midsubstance failures (N = 2) and pullouts (N = 5) at 6 weeks. Histologic evaluations revealed progressive and complete incorporation of the bone block in the femoral tunnel, but only partial incorporation of the tendinous part of the graft in the tibial tunnel. The differences demonstrated at 3 and 6 weeks may be a result of the remodeling process of the midsubstance of the graft as the interfaces within the osseous tunnels mature.

Patellar fractures associated with medial-third bone-patellar tendon-bone autograft ACL reconstruction.

Patella fractures following anterior cruciate ligament (ACL) reconstruction are a recognized but rarely reported complication. To our knowledge, 24 reports of patella fractures after ACL reconstruction using the central-third patella-tendon autograft have been reported in the literature. Patellar fractures associated with the use of the medial-third bone-patellar tendon-bone autograft have not been reported. This article describes four cases of patellar fractures in 478 ACL reconstructions between 1992 and 1999, using the medial third of the patellar tendon graft. All of them were transverse fractures of the patella but only one was displaced. All patients suffered local injury to the donor knee between 2 and 4 months postoperatively. No significant differences in the final outcome were noticed between the cases complicated with patellar fracture and those with uncomplicated ACL reconstructions.

Structure and function of the healing medial collateral ligament in a goat model.

In this study knee joint function with a healing medial collateral ligament (MCL) at six weeks was examined with a robotic/universal force-moment sensor testing system during the application of two loading conditions: (1) 5 Nm valgus moment and (2) 67 N anterior load. Additionally the structural properties of the femur-MCL-tibia complex and the mechanical properties of the MCL substance were determined by uniaxial tensile tests. The histological appearance of the healing MCL was also observed. At 30 degrees and 60 degrees of knee flexion, valgus rotation of the healing knee was significantly increased compared to the sham. The in situ force in the healing MCL was significantly lower (34+/-17 N vs 54+/-12 N) at the same flexion angles (50+/-10 N vs 62+/-7 N). The anterior translation of the knee had returned to normal values at 30 degrees and 60 degrees of knee flexion. However, no differences could be found between the corresponding in situ forces in the healing MCL at all flexion angles examined during application of an anterior load. The stiffness of the healing group (52.5+/-19.4 N/mm) was significantly lower than the sham group (80.3+/-26.4 N/mm) (p<0.04). The modulus of the healing group was also significantly decreased (p<0.05). The findings suggest that the tensile properties of the healing goat MCL and valgus knee rotation have not returned to normal at six weeks after an isolated MCL rupture, however, anterior translation appeared to return to sham levels.

The biomechanical interdependence between the anterior cruciate ligament replacement graft and the medial meniscus.

To establish a quantitative biomechanical relationship between the anterior cruciate ligament graft and the medial meniscus, 10 human cadaveric knees were examined using the robotic/universal force-moment sensor testing system. In response to a combined 134-N anterior and 200-N axial compressive tibial load, the resulting kinematics of the knee and the in situ forces in the anterior cruciate ligament, the anterior cruciate ligament graft, and the medial meniscus were measured. Anterior tibial translation significantly increased after anterior cruciate ligament transection, between 6.8 +/- 2.3 mm at full extension and 12.6 +/- 3.3 mm at 30 degrees of flexion. Consequently, the resultant forces on the medial meniscus, ranging from 52 +/- 30 N to 63 +/- 51 N between full extension and 90 degrees of knee flexion in the intact knee, were doubled as a result of anterior cruciate ligament deficiency. However, after anterior cruciate ligament reconstruction, anterior tibial translations were restored to the levels of the intact knee, and thus the forces on the medial meniscus were restored as well. Likewise, the in situ forces in the anterior cruciate ligament replacement graft increased between 33% and 50% after medial meniscectomy.

Posterior cruciate ligament architecture: evaluation under microsurgical dissection.

PURPOSE: Our objective was to verify the fiber anatomy of the posterior cruciate ligament (PCL) and to measure the main dimensions and the femoral and tibial attachment site distances of the ligament after microsurgical dissection. We hypothesized that PCL anatomy is more complex than the 2 traditionally characterized bands. TYPE OF STUDY: This is a purely anatomic description of microdissections of the PCL, focused on the fine anatomy of the ligament. MATERIALS AND METHODS: Twenty-four fresh-frozen cadaveric knees were dissected using magnifying loupes and an operative microscope, being careful to avoid creating artificially separated bundles. The main dimensions of the PCL were measured using a micrometer. RESULTS: The anterior, central, posterior-longitudinal, and posterior-oblique were the 4 fiber regions identified based on their orientation and the osseous sites of their insertions. These were partially separable anatomically but were functionally distinct. The anterior and central fiber regions made up the bulk of the ligament, while the remaining 15% consisted of the posterior fiber regions. During manual joint motion, the behavior of these fiber regions was observed. The anterior fiber region appeared to be the most nonisometric and remained in tension mainly between 30 degrees and 90 degrees of flexion. The posterior fiber regions appeared to be the most isometric (especially the posterior-oblique) and remained in tension mainly in extension and partially in deep flexion. The central fiber region appeared to have an intermediate behavior and remained in tension mainly between 30 degrees and 120 degrees of flexion. Additionally, it appeared to be the widest of all fiber regions. CONCLUSIONS: These findings should be of interest and help in interpreting some of the anatomy encountered during arthroscopic examination of the PCL, both from the anterior and posterior lateral portals. Furthermore, this information should prove useful in selecting treatment for the PCL.

Tissue engineering of ligament and tendon healing.

Ligaments and tendons are bands of dense connective tissue that mediate normal joint movement and stability. Injury to these structures may result in significant joint dysfunction because they either heal by production of inferior matrix or do not heal at all. The process of ligament and tendon healing is complex and the roles of cellular and biochemical mediators continue to be elucidated. The expression of growth factors and growth factor receptors is modulated after injury, and cells from healing tissues are responsive to growth factors. Tissue engineering offers the potential to improve the quality of ligaments and tendons during the healing process. The concept is based on the manipulation of cellular and biochemical mediators to affect protein synthesis and improve tissue remodeling. Recently, novel techniques such as application of growth factors, gene transfer techniques, and cell therapy have shown promise and may become effective biologic therapies in the future. Many groups have been successful in introducing marker and therapeutic genes into ligaments and tendons. Cell therapy involves the introduction of mesenchymal progenitor cells as a pluripotent cell source into the healing environment. The combination of cell therapy with growth factor application via gene transfer offers new avenues to improve ligament and tendon healing.

Nerve and vessel injuries during high tibial osteotomy combined with distal fibular osteotomy: a clinically relevant anatomic study.

Based on our clinical experience and an anatomical study, we examined the conditions under which injury to the popliteal artery, tibial nerve or peroneal nerve and its branches may occur during high tibial osteotomy. In 250 high tibial osteotomies performed in our department, we observed the following intraoperative complications. (1) The popliteal artery was severed in 1 patient and repaired by the same surgical team using a microsurgical technique. (2) A tibial nerve paresis also occurred in 1 patient. (3) In 3 patients, temporary palsy of the anterior tibialis muscle was documented. (4) In 4 other patients, palsy of the extensor hallucis longus occurred. To investigate the causes of these complications in the popliteal artery, tibial nerve and branches of the peroneal nerve, we dissected the neurovascular structures surrounding the area of the osteotomy in 10 cadaveric knees and performed a high tibial osteotomy in another 13 cadaveric knees. We concluded the following. (1) The popliteal artery and tibial nerve are protected, at the level of the osteotomy, behind the popliteus and tibialis posterior muscles. Damage can occur only by placing the Hohman retractor behind the muscles. The insertion of the muscles is very close to the periosteum and can be separated only with a scalpel. (2) The tibialis anterior muscle is innervated by a group of branches arising from the deep branch of the peroneal nerve. In two-thirds of the dissected knees, we found a main branch close to the periosteum, which can be damaged by dividing the muscle improperly or due to improper placement and pressure of the Hohman retractor. This may explain the partially reversible muscle palsy. (3) The extensor hallucis longus is also innervated by 2-3 thin branches, arising from the deep branch of the peroneal nerve, but in 25% of the specimens, only one large branch was found. This branch is placed under tension by manipulating the distal tibia forward. Thus, it may be damaged by the Hohman retractor during distal screw fixation, tensioned by hyperextension or directly injured during midshaft fibular osteotomy.

Difficulties and early results of the endoscopic carpal tunnel release using the modified Chow technique.

In reporting on the preliminary results of our series of 76 patients, this paper aims to identify potentially complicating aspects of endoscopic carpal tunnel release (ECTR) using the two-portal Chow technique, and to recommended solutions, based on our early experience, which enhance the ease and safety of this minimally invasive technique. Of the first 24 patients, 16 cases required conversion to an open procedure. Based on these initial cases, we developed certain modifications of the Chow technique which precluded any need for open conversion in the 60 remaining cases. During a follow-up interval ranging from 4 to 24 months, there was no recurrence of carpal tunnel symptoms, and the average time to resumption of work activity was 14 days. The complication rate was 5% and included one case of transient hypesthesia, one case of extended hematoma, and one hypersensitive scar. All complications resolved at subsequent follow-up. In our experience, correct positioning of the hand, proper injection of local anesthetic, use of magnifying loupes, and correct use of instruments are essential for a safe and successful procedure.

Anterior cruciate ligament reconstruction with the press-fit technique. 2-5 years followed-up of 42 patients.

42 patients underwent anterior cruciate ligament (ACL) reconstruction with the press-fit technique. The ACL was reconstructed with a bone-tendon-bone graft from the medial third of the patellar tendon. The graft was stabilized without screws in the femur and tibia by press-fit. To imitate the anatomical functioning of the ACL, the femoral bone block was placed with the tendon close to the over-the-top position. The tibial block was then placed in a trough on the tibia, so that the ligament fibres were parallel and tight during extension and slightly inverted during flexion. At evaluation mean 41 (25-61) months postoperatively, the mean Lysholm score was 93 (80-100) points, the mean activity level was 6 (3-10) points, and the mean translation of the tibia head, measured by the KT-1000 arthrometer (side-to-side difference), was 2 (0-7) mm. Only 3 of the patients suffered loss of extension (5 degrees). Patients who underwent reconstruction at least 4 months after the injury had better results than those who were operated earlier. The press-fit method allowed for anatomic substitution of the ACL with a stable graft without the disadvantages associated with screws. This method gave early postoperative functioning of the knee and good mid-term results.