Distal humeral replacement after failed continuous passive motion in a T-condylar fracture

The extent to which ribosomal RNA is directly involved in the function of ribosomes has important implications for both the mechanism of translation and the molecular origins of life. Detailed evidence has accumulated that places the anticodon and acceptor ends of tRNA in close proximity to conserved features of rRNA in the ribosome. Recent studies are providing evidence that these features are important for ribosomal function.     

Prosthetic replacement of the anterior cruciate ligament in dogs

Prosthetic cruciate ligaments are now used clinically. Long-term results are not yet available and for that reason an attempt has been made to reproduce the clnical situation in dogs. Post-traumatic osteoarthritis was inevitably noted following simple excision of the anterior cruciate ligament in a control group of 10 animals. Different prosthetic materials were used and their breaking point was compared with that of normal anterior cruciate ligaments. The longest follow-up period was 6 months. Although some animals had no clinically demonstrable instability, at autopsy all prosthetic ligaments were noted to have failed. The degree of post-traumatic osteoarthritis was directly related to the duration of follow-up. The causes of failure of the prosthetic ligament do not appear to be related to the method of anchorage to bone but rather to the type of prosthetic material used. Although the tensile strength may occasionally have been sufficient, the materials did not have the required elastic characteristics to meet the physiologic demands of a normal cruciate ligament.     

The semitendinosus tendon as replacement for the anterior cruciate ligament

This article describes the history, advantages, biomechanical properties, operative technique, and results of replacement of the anterior cruciate ligament using the semitendinosus tendon. After arthroscopic ACL replacement using the doubled semitendinosus tendon in combination with an extraarticular lateral repair in 65 consecutive patients (20 acute, 45 chronic instabilities) we found after 2 years in 51 patients (78%) an excellent or good result with less than 3 mm difference in the Lachman test measured with the KT-1000 arthrometer (MMD). After 6 years 40 out of the 45 patients with chronic instabilities could be examined again. Only 28 patients (70%) showed a difference in anterior translation of less than 3 mm. A positive pivot shift sign could be seen in 11% of the patients after 2 years and in 20% after 6 years. The Tegner score increased from 6.0 after 2 years to 6.2 after 6 years, the Lysholm score decreased from 93 to 91 in the same interval. 89% of the patients had a free range of knee motion after 2 years and 92.5% after 6 years. There were 10% normal, 50% nearly normal, 25% abnormal, and 15% severely abnormal knees in the IKDC evaluation after 6 years. In the last 4 years we are using the quadrupled semitendinosus tendon in an arthroscopic single incision technique for ACL replacement with femoral Endobutton fixation, because the doubled semitendinosus tendon seems to elongate over time. After 23 months on average (12-36 months) the preoperative anterior translation of 7.5 mm could be decreased to 1.9 mm in 35 patients.     

Arthroscopic replacement of the anterior cruciate ligament with a double semitendinosus tendon

At the university hospital of emergency surgery in Innsburck and at the emergency services department of the hospital in Schwaz, anterior cruciate ligament reconstruction was performed in 467 patients between January 1992 and September 1993. In 117 cases, a double semitendinous tendon was used as an autograft. A total of 60 of these patients were followed up at an average of 20 months (13-33) after reconstruction. The results were rated according to the OAK and the Tegner scores. Objective measurements of instability were carried out by a KT 1000 arthrometer. In addition, 21 patients underwent computer-interfaced dynamometer testing using a Cybex 6000. Standardized loading of the thigh muscles was performed at angular velocities of 60 degrees/s (3 repetitions) and 240 degrees/s (30 repetitions): peak torques and total work were analyzed. The mean age was 23.5 years (17-55): 48 were male, 21 female. The main reasons for the ACL ruptures were sports injuries (51 cases). The patients were classified into three groups according to the data of the repair (group 1 reconstruction up to 1 week after trauma-28 patients: group 2: reconstruction between the 2nd and 6th week after trauma-15 patients: group 3: reconstruction 6 and more weeks after trauma-26 patients). In group 1. additional ruptures of the menisci. lesions of the MCL. and chondromalacia were seen in 71.4%. in group 2 in 73.3% and in group 3 in 80.8%. The average rating in the OAK score was 90.16 points: 38 patients (55.70%) had excellent results. 18(26.09%) were good. 9(13.04%) were fair and 4(5.80%) were poor. The Tegner activity score showed a reduction of 0.36 points on average. The largest amount of anterior translation was performed with the KT 1000 manual drawer test (2.29 mm on average compared with the contralateral side). Dynamometer testing showed a statistically significant difference in flexor and extensor mechanism (compared with the non-involved side) in both peak torques and total work. A repeat arthroscopy became necessary in five cases: arthrofibrosis in three and incipient joint infection in two cases.     

Screw home motion after total knee replacement

The objective of this study was to evaluate the effect of muscle force and the posterior cruciate ligament on screw home motion in patients with total knee replacement in a posterior cruciate ligament retaining prosthesis (10 knees) and a posterior cruciate ligament substituting prosthesis (10 knees). Screw home motion was examined with only active extension and with two types of externally loaded active extension (2 kg and body weight). Screw home motion was measured with a 6 degrees of freedom electrogoniometer (instrumented spatial linkage). Retaining the posterior cruciate ligament maintained screw home motion, with and without external load to muscles, whereas substituting the posterior cruciate ligament maintained screw home motion only under the full external load of body weight. This was not seen with a 2-kg external load. As for the normal knee, it appears that screw home motion of a prosthetic knee is influenced, not only by the presence of ligamentous structures, but also by the activity of the muscles. The activity of the muscles may have a much greater effect on screw home motion with currently used prosthetic designs than does the presence of ligamentous structures.     

The effect of immediate weightbearing after anterior cruciate ligament reconstruction

Immediate weightbearing has been advocated after anterior cruciate ligament reconstruction and is thought to enhance the return of quadriceps muscle activity and knee extension range of motion without jeopardizing graft integrity. This study examined the effect of immediate weightbearing after anterior cruciate ligament reconstruction on the return of vastus medialis oblique electromyography activity, knee extension range of motion, knee stability, physical examination, Lysholm score, and anterior knee pain. Forty-nine patients (24 men and 25 women) undergoing endoscopic central third patella tendon autograft reconstruction were randomized prospectively into two groups. Group 1 patients underwent immediate weightbearing as tolerated. Group 2 patients were kept nonweightbearing for 2 weeks. All measurements were taken before surgery, 2 weeks after surgery, and between 6 and 14 months (average, 7.3 months) followup. There was no effect of weightbearing on knee extension range of motion or vastus medialis oblique function at followup. In addition, knee stability was not compromised after surgery. Seven of 20 (35%) nonweightbearing patients and only two of 25 (8%) immediate weightbearing patients reported anterior knee pain at followup. Overall, immediate weightbearing did not compromise knee joint stability and resulted in a better outcome with a decreased incidence of anterior knee pain.     

Principles and value of isokinetic evaluation in ruptures of the anterior cruciate ligament

Isokinetic muscular evaluation allows to appreciate the knee joint functional patterns in conditions close to sports activities. Analyzing bilateral symmetry and agonist/antagonist ratios of the lower extremity, this method is a useful index for the objective evaluation of ligament-deficient knees. 106 patients with a chronic ACL deficient knee sustained a presurgery isokinetic evaluation. 94 patients had a post-operative evaluation and 13 a pre and post-surgery evaluation. All patients were simultaneously evaluated by clinical examination and measures of instrumental knee laxity (KT 1000). Results showed that isokinetic performance was not correlated to the objective laxity as measured with the KT 1000 but was correlated to 1) the type of laxity (i.e. associated postero-lateral laxity), 2) the functional level of activity, and 3) the time of disability. Best functional results were obtained in patients whose injured knee hamstring/quadriceps (H/Q) ratio was close to the uninjured knee H/Q ratio. The mean quadriceps deficit was over 15 per cent for 75 per cent of the patients one year after surgery, and for 50 per cent of the patients after two years. The quadriceps deficit was not parallel to the length of the autograft taken from the extensor mechanism. Isokinetic evaluation is a guideline for rehabilitation allowing specific strengthening of the weaker muscular groups.     

Gait adaptations before and after anterior cruciate ligament reconstruction surgery

Gait analyses of rehabilitated individuals with anterior cruciate ligament (ACL) deficiency and reconstruction have identified the final adaptations of increased hip extensor torque and hamstring electromyography (EMG) and decreased knee extensor torque and quadriceps EMG during stance. The initial adaptations to injury and surgery are, however, unknown as are the factors that influence the development of the adaptations. Identification of the initial response to injury would provide a basis for determining whether the final adaptations are learned automatically or if they are the result of a lengthy training period in which various factors may affect their development. The purpose of the study was to evaluate the initial effects of ACL injury and reconstruction surgery on joint kinematics, kinetics, and energetics, during walking. Injured limbs from nine subjects with ACL injury were tested 2 wk after injury, and 3 and 5 wk after surgery. Ten healthy subjects were tested. Kinematic and ground reaction data were collected and combined with inverse dynamics to calculate the joint torques and powers. A knee extensor torque throughout most of stance was observed in the injured limbs at all test sessions. This result was in conflict with previous observations of reduced extensor torque or a flexor torque in rehabilitated patients with ACL reconstruction and patients with ACL deficiency. This result also differed from the typical midstance extensor then flexor torque in healthy control subjects. Trend analysis showed a significant (P < 0.001) change in average position at the hip and knee, extensor angular impulse at the hip, and positive work done at the hip 3 wk after surgery followed by a partial rehabilitation at 5 wk after surgery. Power and work produced at the knee were reduced fivefold (P < 0.001) after 5 wk of rehabilitation and did not recover to pre-surgical levels. The existence of a long-lasting knee extensor torque 2 wk after injury indicated that the adaptation process to ACL deficiency is lengthy, requiring many gait cycles, and that numerous factors could be involved in learning the adaptations.     

Mid-term outcome after surgically managed re-rupture of the anterior cruciate ligament

This retrospective study shows the results in 30 patients of revision surgery on their reruptured ACL. The follow-up time was 30 months on average (range 10-54 months). The follow-up examination included subjective (Lysholm score, Tegner activity level rating score), clinical and radiological criteria and also instrumental laxity testing with the KT-1000 arthrometer. The overall evaluation was done according to the IKDC score. The follow up showed subjective and objective results almost equal to those after primary surgery on ACL. The IKDC score revealed certain abnormal and highly abnormal results, which demonstrated that revision ACL surgery gives poorer results than primary surgery. Nevertheless, we recommend reconstruction of a torn ACL even in a revision case to restore the knee function and prevent further menisceal and chondral damage and degeneration.     

The impact of surgical timing on postoperative motion and stability following anterior cruciate ligament reconstruction

A prospective study was designed to determine the impact of surgical timing on postoperative motion and stability following anterior cruciate ligament (ACL) reconstructive surgery. The study population was limited to acute ACL ruptures from downhill skiing undergoing arthroscopic ACL surgery without arthrotomy or surgical intervention for other ligamentous structures; 185 patients were entered into four separate groups based on the time interval from injury to surgery. Motion and stability were tested at multiple time points from the index surgery and adverse events were recorded. We found no statistical difference in restoration of extension or flexion in any group at any time point. KT-1000 data at 12 months showed a side-to-side difference of < or = 3 mm in 94%, with 6% showing a side-to-side difference of > 3 and < or = 5 mm. We conclude that, in this population, by using modern arthroscopic surgical techniques and an aggressive postoperative physical therapy protocol, motion and stability can be restored in a high percentage of patients and that surgical success is independent of the timing of surgery.     

Posterior cruciate supplementing total knee replacement using conforming inserts and cruciate recession. Effect on range of motion and radiolucent lines

This study was performed to determine if a sagittally curved conforming tibial insert can be used with a retained, but balanced, posterior cruciate ligament without deleterious effects on range of motion (ROM) and tibial radiolucencies, as compared with a flatter insert that is less conforming and does not require cruciate balancing. The authors reviewed 50 consecutive primary knees implanted with flatter posterior lipped inserts and 50 consecutive primary knees with curved inserts and posterior cruciate ligament balancing. The average ROM for both groups was the same postoperatively as preoperatively: 111 degrees for the posterior lipped inserts and 113 degrees for the curved inserts. The incidence of tibial radiolucent lines was 8% for both groups. The authors conclude that sagittally curved, more conforming tibial inserts with retained, but balanced, posterior cruciate ligaments, do not adversely effect ROM and tibial radiolucencies. Their use forms an attractive compromise between the schools of cruciate preservation and cruciate substitution, maximizing their advantages while minimizing their disadvantages. Functional ROM can be achieved while bone stock is preserved, the joint line is restored, and wear characteristics are improved.     

Postoperative pain after anterior cruciate ligament reconstruction using a transligamentous approach

Anterior cruciate ligament reconstruction by free patellar tendon graft was performed using 2 different surgical approaches to the intercondylar notch in 67 consecutive patients with chronic anterior cruciate ligament insufficiency. In the first 30 patients (Group A), the traditional medial parapatellar arthrotomy with lateral luxation of the patella was done, whereas in the last 37 patients (Group B) a transpatellar tendon approach was used. Postoperative pain was managed by analgesics and, in patients who had epidural anesthesia, by administration of bupivacaine in indwelling catheters. Generally, the analgesics and bupivacaine were given immediately on request to establish comfort at rest and to permit range of motion exercises without severe pain. Compared with those in Group A, the patients of Group B had a significantly longer period from the first dose of analgesic or bupivacaine to the second, and the total number of doses of analgesic or bupivacaine was significantly lower. In the subgroup of patients with epidural anesthesia (21 in Group A and 32 in Group B), the Group B patients required significantly less analgesics, as doses equivalent to 10 mg of morphine, compared with that of Group A.     

Anterior knee laxity and loss of extension after anterior cruciate ligament injury

This study was performed to examine the relationship between knee extension loss and the length of time after injury. We also wanted to compare anterior laxity in anterior cruciate ligament-injured knees in the early and late stages of injury. Loss of knee extension was measured in 81 patients with anterior cruciate ligament injury using lateral radiography with the injured leg relaxed and elevated. Extension loss was defined as the difference in maximal extension angle between the injured and uninjured knees. Average loss of extension was 3.6 degrees in the 17 knees in which the anterior cruciate ligament had been torn 3 weeks or less before examination (the acute injury group) and 0.6 degree in the 64 knees in which the anterior cruciate ligament had been torn more than 3 weeks before examination (the chronic injury group). The extension loss in the acutely injured knees was significantly greater compared with that in the uninjured knees and in the chronically injured knees. Arthrometric measurements using the KT-1000 arthrometer were reliable to diagnose an acute tear. There was no correlation between the degree of extension loss and arthrometric anterior knee laxity measurements. In 12 patients, the initial extension deficit in the early stage of injury significantly resolved with time, and manual maximum arthrometric measurements of anterior knee laxity improved spontaneously with time.     

Sports capacity after rupture of the anterior cruciate ligament--surgical versus non-surgical therapy

Using a new rating system (Innsbruck Knee-Sports Rating Scale) 75 patients 5 to 6 years after ACL-injury have been compared to their sports activity (47 patients with ACL reconstruction and 28 conservative treated patients). Under the viewpoint of knee load and especially the demand on stability sports activities have been divided into 3 categories: High Risk, Low Risk and Non Risk Pivoting Sports. Operative therapy shows an advantage in High Risk Pivoting sports (e.g. soccer, basketball) and in Low Risk Pivoting (e.g. running, hiking) sports, expressed by fewer knee related symptoms and higher participation levels. In the Non Risk Pivoting category (e.g. swimming, cycling) good results could also be achieved by conservative therapy. The careful evaluation of each patient's sports activities is therefore an important factor in the decision for the right therapy on one hand, and for comparing the results of different therapy programs or patient collectives on the other.     

Augmented anterior cruciate ligament replacement with the Kennedy-LAD (ligament augmentation device)--long term outcome

The ligament augmentation device (Kennedy-LAD) is used to protect tendon grafts during the posttransplantation decrease in strength in anterior cruciate ligament (acl) reconstructions. The augmentation with the LAD is based on the concept of load sharing. Since 1983 we used the LAD in acl-reconstructions in 856 patients. In 63 cases we had to treat complications like infection (8), recurrent effusions (21), arthrofibrosis (34). The overall results are good with respect to stability, regain of strength and sports activity. In 73 cases resurgery was necessary because of synovitis (7), LAD-rupture due to re-injury (9), fatigue-rupture of the LAD (22), meniscal tears (35), 2.7 +/- 2.3 years (range: 2 months to 10 years) after LAD implantation. Modern techniques in acl reconstruction lead to comparable results without synthetic augmentation. Therefore, we now recommend the use of a LAD only in cases of repeated acl replacement with week tendon grafts, to avoid an allograft.     

Effects of continuous passive motion and immobilization on synovitis and cartilage degradation in antigen induced arthritis

OBJECTIVE: To determine the effects of continuous passive motion (CPM) and immobilization on synovitis and cartilage degradation in an experimental model of chronic inflammatory, antigen-induced arthritis. METHODS: After bilateral arthritis induction of knee joints in 22 NZW rabbits, one knee was immobilized with a flexion splint while the opposite knee received CPM. RESULTS: After 2 weeks (n = 10), the CPM treated knees had significantly greater joint swelling, synovial effusion, and histologic synovitis scores compared to its opposite immobilized knees. However, the total cartilage degradation score showed no statistically significant difference between the two treatments. When the treatments were discontinued after 2 weeks and animals were allowed intermittent active motion of both knees in cages for 4 weeks (n = 12), no statistically significant difference in joint swelling, synovial effusion, and histologic synovitis score was observed between the 2 treatments. The articular cartilage degradation, however, was significantly greater in the immobilized knees compared to its opposite CPM treated knees. Five of 12 immobilized knees had articular surface erosion compared to none in the CPM treated knees. Loss of cellularity was also significantly greater in the immobilized knees. CONCLUSION: Although CPM produced greater synovitis at 2 weeks, articular cartilage was better preserved in the knees treated with CPM than immobilization at 6 weeks.     

Gait biomechanics are not normal after anterior cruciate ligament reconstruction and accelerated rehabilitation

PURPOSE: Accelerated rehabilitation for anterior cruciate ligament (ACL) injury and reconstruction surgery is designed to return injured people to athletic activities in approximately 6 months. The small amount of empirical data on this population suggests, however, that the torque at the knee joint may not return until 22 months after surgery during walking and even longer during running. Although the rehabilitation has ended and individuals have returned to preinjury activities, gait mechanics appear to be abnormal at the end of accelerated programs. The purpose of this study was to compare lower extremity joint kinematics, kinetics, and energetics between individuals having undergone ACL reconstruction and accelerated rehabilitation and healthy individuals. METHODS: Eight ACL-injured and 22 healthy subjects were tested. Injured subjects were tested 3 wk and 6 months (the end of rehabilitation) after surgery. Ground reaction force and kinematic data were combined with inverse dynamics to predict sagittal plane joint torques and powers from which angular impulse and work were derived. RESULTS: The difference in all kinematic variables between the two tests for the ACL group averaged 38% (all P < 0.05). The kinematics were not different between the ACL group after rehabilitation and healthy subjects. Angular impulses and work averaged 100% difference for all joints (all P < 0.05) between tests for the ACL group. After rehabilitation, the differences between injured and healthy groups in angular impulse and work at both the hip and knee remained large and averaged 52% (all P < 0.05). CONCLUSIONS: Results indicated that after reconstruction surgery and accelerated rehabilitation for ACL injury, humans walk with normal kinematic patterns but continue to use altered joint torque and power patterns.     

Physiological and mechanical adaptations of rabbit medial collateral ligament after anterior cruciate ligament transection

Progressive physiological and mechanical changes in the medial collateral ligament of the adult rabbit were investigated for as long as 48 weeks after disruption of the anterior cruciate ligament. Eighty-one New Zealand White rabbits were separated into experimental, sham-operated control, and normal control groups. The experimental group underwent unilateral transection of the right anterior cruciate ligament, sham-operated animals served as controls for comparison, and normal animals were evaluated as age-matched, undisturbed (no surgery) controls. Blood flow to the medial collateral ligament (as a physiological measure) and mechanical function (structural and material properties) were assessed at 6, 14, and 48 weeks. The results indicated that loss of the anterior cruciate ligament leads to early mechanical deterioration of the medial collateral ligament with a corresponding loss of physiological homeostasis. Six to 14 weeks after the transection, values for cross-sectional area of the medial collateral ligaments rapidly increased to 1.5 times control values. The ligament became twice as large as the control ligament by 48 weeks. Concomitantly, medial collateral ligament stress at failure of the medial collateral ligament complex decreased rapidly 6-14 weeks after the transection and eventually fell to one-half that of controls by 48 weeks. In terms of low-load behaviour, laxity and load relaxation were significantly greater than that of controls 6 weeks after transection and were further increased by 14 weeks. By 48 weeks, laxity values had recovered somewhat and load-relaxation measures had recovered to near control values. At both 6 and 14 weeks, a statistically significant elevation in blood flow was demonstrated compared with controls. By 48 weeks, however, blood flow was no different from that of the sham-operated control. Thus, early after transection of the anterior cruciate ligament, both low-load and high-load mechanical properties of the medial collateral ligament deteriorated and the rate of blood flow was temporarily elevated. By 48 weeks, blood flow declined to near control values, with a corresponding recovery in viscoelastic behaviour. These findings suggest that, after transection of the anterior cruciate ligament, viscoelastic behaviour of the medial collateral ligament may be related to changes in blood flow and that restoration of normal flow patterns and vascular responses may be linked to the recovery of some low-load mechanical properties in the anterior cruciate ligament-deficient medial collateral ligament.