Biomedical subjects
Publications and source records attributed to D M Lintner.
SUMMARY: Recent progress in meniscal repair technology has included the development of bioabsorbable implants that can be inserted without a posterior incision. Satisfactory success rates have been reported. Reports of complications have been rare. We present 5 cases of failure of a biodegradable meniscal repair implant, each of which presented as a subcutaneous foreign body.
This study examined whether the addition of quadriceps contraction to standard Merchant views provides additional useful information in the evaluation of patients with extensor mechanism malalignment. Fifteen patients (23 knees) with anterior knee pain due to lateral patellar compression syndrome and 22 control patients (44 knees) underwent standard Merchant views with the quadriceps relaxed and with an isometric isotonic contraction. Congruence and lateral patellar angles were measured for all groups. Although the congruence angle differed significantly between the control and symptomatic groups with the quadriceps contracted (P< or = .001), this difference also was seen without quadriceps contraction. There was also no significant difference within each group on addition of quadriceps contraction. No significant difference existed between the two groups for lateral patellar angle with quadriceps contraction. The addition of a controlled isometric quadriceps contraction did not add to the diagnostic yield of the standard Merchant view in terms of a predictable change in measured radiographic parameters.
The purpose of this study was to evaluate the effect of simulated closed-chain exercise on anterior translation in the anterior cruciate ligament (ACL) reconstructed knee comparing patellar tendon grafts secured with endoscopic and two-incision techniques. ACL reconstructions, were performed on five matched pairs of fresh frozen cadaver lower extremities. One of each pair had endoscopic (inside-out) placement of the femoral interference screw and other had outside-in femoral screw placement. A model for closed-chain exercise was developed to simulate half squat exercises using a custom apparatus on the Material Testing machine with a 356 N (80 lb) axial load and 40 N (9 lb) static hamstring force. Knee motion from near full extension to 60 degrees flexion was achieved by varying the quadricep force. One thousand squats were performed, and KT-1000 arthometry was done before and after cycling each specimen. The femur-graft-tibia constructs were then stressed to failure. Closed-chain cycling resulted in no significant change in anterior translation in either group. The mean maximum load to failure of the femur-graft-tibia construct was 340.4N in the one-incision group and 434.2 N in the two-incision group. P=.048 was considered statistically significant. Anterior translation did not increase after 1,000 simulated half knee bends in either the one- or two-incision groups. Shallow knee bends are an important part of aggressive rehabilitation programs, and our data support the position that these closed-chain exercises do not deleteriously affect the graft. Though the maximum strength to failure differed significantly between the one- and two-incision groups, both techniques offered sufficient strength to withstand an aggressive simulated rehabilitation protocol.
This study compares the early functional outcomes of anterior cruciate ligament (ACL) reconstruction using a one-incision endoscopic technique versus a two-incision arthroscopically assisted technique. Thirty patients with chronic ACL-deficient knees were randomly assigned to either group 1 (one-incision technique; 15 patients) or group 2 (two-incision technique; 15 patients). Middle third ipsilateral patellar tendon was used in all reconstructions. All patients followed the same home-based accelerated rehabilitation protocol. The International Knee Documentation Committee scoring system was used to assess pre- and postoperative knee function. The mean length of follow-up was 17 months for group 1 and 15 months for group 2. Three patients were lost to follow-up in group 2. Patients in group 1 achieved a mean one-leg hop value of 89% of the uninjured side while group 2 patients averaged 92%. The mean side-to-side difference in anterior tibial translation was 2 mm in both groups at manual maximum translation. The mean isokinetic quadriceps strength at 300 degrees/second of the operated side 1 year after surgery was 83% of normal for group 1 versus 73% for group 2. Both groups achieved maximum range of motion within 3 months. There was no statistically significant difference between the outcomes of the one- and two-incision techniques for ACL reconstruction. All patients in both groups had improved stability and function of their operative knees compared with their preoperative condition.
Chronic patellar ligament ruptures, on which failed reconstruction attempts have been made, cause structural changes in the quadriceps mechanisms with marked fixed proximal migration of the patella. Before reconstruction, the position of the patella must be normalized. When using Ilizarov principles and an Ilizarov external fixator to treat these ruptures, full weightbearing and range of motion can be maintained throughout the pre- and postreconstruction period. This previously unreported technique has been used in 2 patients with chronic patellar ligament ruptures in whom reconstruction attempts had failed. Successful results obtained with this procedure warrant its consideration for this rare but disabling problem.
Nonspinal skeletal tuberculosis is a rare, indolent disease that is often difficult to diagnose. The incidence in the United States has recently increased. Pain and swelling are common symptoms. Radiographs may reveal normal findings, or in more advanced cases, demonstrate osteopenia, marginal erosions, and eventually, joint space narrowing and destruction. Treatment depends on the extent of the disease. Prolonged therapy with antitubercular agents is the mainstay of treatment. Synovectomy, osseous debridement, and arthrodesis also have a role in the treatment of this infection.
Eighteen consecutive patients (average age, 66.4 years at arthroscopy) who had a previous total knee arthroplasty underwent arthroscopic resection of a transverse suprapatellar fibrous band, which was causing patellar snapping and jumping as it impinged on the intercondylar notch portion of the femoral component during active extension (tethered patellar syndrome). Fourteen patients were available for followup at an average of 56 months (range, 37-91 months). All patients had complete relief of the patellar symptoms. One patient had a recurrence of symptoms 10 months after arthroscopy but remained symptom free 30 months after repeat resection. All are currently symptom free and are classified as having excellent results. The average range of motion is 1 degree to 115 degrees. There were no complications attributable to the arthroscopy. The tethered patellar syndrome has been noted by various authors, and has been most commonly treated by arthrotomy. At arthroscopy, a transverse suprapatellar fibrous band was seen to catch on the intercondylar notch of the femoral component, snapping free as the knee extended past approximately 30 degrees. In this population, excellent long-term results were achieved with arthroscopic removal of the transverse suprapatellar band.
Neurologic outcomes were correlated with the cervical canal diameter for 33 patients who sustained unilateral or bilateral facet fractures, dislocations, subluxations, or perch injuries during a 9-year period. Lateral roentgenograms (target distance, 72 in.) were used to measure the canal and calculate the canal-body ratio (Torg's ratio) at the level of the vertebral injury. Frankel's classification system was employed to compare initial and final neurologic function. The most important factors that determined the long-term functional results after unilateral or bilateral injuries in the cervical spine were the degree of vertebral trauma and the severity of the initial neurologic deficit. There was no correlation between the preinjury canal diameter or ratio and the severity of neurologic injury or the prognosis. Also, neurologic injuries were more common and more severe in patients with bilateral facet injuries. No patients with complete injuries had an improvement in their Frankel grade.
Glenoid dysplasia is a rare congenital abnormality that may be associated with vague shoulder pain, limitation of motion, and weakness of the upper extremity. In many cases it is an incidental finding on chest roentgenogram, and high-level function is usually possible before the onset of symptoms or degenerative changes. The case of an 18-year-old collegiate football offensive lineman who developed symptoms secondary to previously undetected bilateral glenoid dysplasia is reported. Roentgenograms demonstrated dysplastic scapular necks, and arthrography showed a deformed, constricted shoulder capsule. Magnetic resonance imaging defined the extent of the cartilaginous anlage, and arthroscopy demonstrated progressive articular cartilage degeneration. Although treatment alleviated the shoulder symptoms at low-level activities, the patient was unable to successfully compete under the extreme demands of an American football lineman.
The purpose of this study was to use magnetic resonance imaging to evaluate various parameters of the patellar tendon during the first year after harvest for anterior cruciate ligament (ACL) reconstruction. Twelve consecutive patients were serially imaged on a 1.5 Tesla GE magnet (GE Medical Systems, Milwaukee, WI) with a dedicated knee coil at 3 weeks, 3 months, 6 months, and 1 year after undergoing ACL reconstruction using a central one-third patellar tendon autograft. The tendon defect was not closed primarily, but the paratenon was approximated. The following measurements were performed: tendon width, defect width, cross-sectional area of the tendon, and tendon length. In addition, the patellar bone harvest site was evaluated for healing. The width of the tendon defect decreased by 62% over 12 months (P < .05). Only two patients showed complete closure of the defect. Tendon width was noted to decrease by 6.5% (P=.017). The ratio of defect width to overall tendon width (designated R) decreased by 58% (P < .05). Tendon length was noted to decrease during this by 8% (P=.037). The tendon cross-sectional area was noted to increase by 9% at 1 year, but this was not found to be statistically significant (P=.39). One year after ACL reconstruction using a central one-third patellar tendon, the tendon defect has begun to reconstitute itself but there is still a significant gap. This persistent defect must be taken into consideration when planning revision ACL surgery using reharvest of the central one third of the patellar tendon. The entire tendon also exhibits a reduction in width and length, while cross-sectional area increases slightly. Complete healing of the graft defect can not be assumed at 12 months post-ACL reconstruction.
Injuries treated at the University of Rochester Section of Sports Medicine over a 7 year period were surveyed. Patients were drawn from professional, intercollegiate (Division III), high school, intramural, and unorganized athletics at the University and the surrounding community. Data on injury diagnosis was available for 4,551 cases, with data on age, gender, and sport of injury available for 3,431 of the cases. The average patient age was 21.6 years, with a peak in the 16 to 19 age group. Patients with fractures had an average age below the overall mean, while those with internal derangement of the knee, patellofemoral pain syndrome, and inflammatory injuries were significantly older than average. Males accounted for 80.3% of all injuries. For both sexes the most common areas injured were the knee and ankle, with sprains/strains the most common injuries. Injuries involving the patellofemoral articulation were significantly more frequent among females. The most common sport of injury was football, with greater than 12 times the number of injuries seen in the next most common sport.
Eight cadaveric lower extremities were examined by three experienced knee surgeons in blinded fashion. The knees were examined with intact anterior cruciate ligaments, sectioned anteromedial bundles, and completely sectioned anterior cruciate ligaments to evaluate detectable laxity changes. Lachman, anterior drawer, lateral pivot shift, and KT-1000 arthrometer testing were performed. Optimized biplanar radiography using a defined spatial coordinate reference system was performed with a 30-pound anterior force at 30 degrees of flexion to confirm clinical findings. Physical examination and arthrometer testing detected no difference between intact and partially sectioned anterior cruciate ligaments; these ligaments were significantly different than completely sectioned ligaments, with the Lachman test being the most sensitive. Despite consistent clinical detection of complete sectioning of the anterior cruciate ligament by both physical examination and arthrometer testing, neither method proved accurate in the diagnosis of isolated tears of the anteromedial bundle, but both did show that partially sectioned anterior cruciate ligament closely resembled intact ligament and differed significantly from completely sectioned ligament, as confirmed by radiologic data. Clinically diagnosed "partial tear" is likely to be complete rupture of the anterior cruciate ligament. Historically, clinically diagnosed partial tears of the anterior cruciate ligament have tended to "progress" to symptomatic instability. Our data imply these patients may have had functionally incompetent ligaments from time of injury and, in fact, were demonstrating the expected natural history of an anterior cruciate ligament-deficient knee.
We examined seven cadaveric knees to determine the radiographic location of the native anterior cruciate ligament insertion sites as well as the location of tunnels used in anterior cruciate ligament reconstruction. Posteroanterior and lateral views at several flexion angles were taken with radiopaque markers around the insertions of the native anterior cruciate ligament and subsequent reconstruction tunnels. The femoral insertion was best seen on the 60 degrees notch view. On the lateral view, the femoral tunnel was easily seen as it crossed the roof of the intercondylar notch; however, because of the angle of the tunnel, the actual entrance into the knee may be well distal and anterior to this location. The tibial insertion and tunnel were easily seen at any flexion angle. The center of the insertion was 40% of the tibial diameter from the anterior margin. The lateral view in extension allowed determination of the tibial tunnel's location in relation to the intercondylar notch roof, but by itself did not allow accurate determination of the femoral tunnel's position. Notch and extension lateral radiographs together provided sufficient information for evaluation of anterior cruciate ligament graft position in a convenient, cost-effective format. Neither view by itself provides enough information to evaluate the position of the graft.
We measured changes in anterior translation of the tibia with sequential sectioning of the bundles of the anterior cruciate ligament and correlated these changes with the clinical examination. Six fresh cadaveric lower extremities were examined by three experienced knee surgeons in a masked fashion with the anterior cruciate ligament intact and after sectioning of the posterolateral bundle, the posterolateral bundle and 50% of the anteromedial bundle, and the entire ligament. Lachman, anterior drawer, and lateral pivot shift tests were performed. Both KT-1000 arthrometer testing (30 pounds) and biplanar radiography demonstrated progressive increases in anterior translation with incremental sectioning of the anterior cruciate ligament. However, significant (P < 0.05) increases in translation were found only after sectioning both the posterolateral bundle and half of the anteromedial bundle and after complete sectioning of the anterior cruciate ligament. The examiners were accurate in their interpretation of the status of the anterior cruciate ligament in 89% of the intact specimens and 80% of completely sectioned ligaments. Only 11% of the examinations correctly diagnosed the anterior cruciate ligament as partially cut when the posterolateral bundle was sectioned. A soft end point to the Lachman examination was noted only after cutting at least 75% of the ligament, but was not always present. Clinical evaluation is accurate in defining intact and completely sectioned anterior cruciate ligaments. However, it is unable to differentiate a sectioned posterolateral bundle from an intact anterior cruciate ligament, or a 75% sectioned ligament from a completely sectioned ligament. The clinical diagnosis of a partial tear of the anterior cruciate ligament is more likely to represent a complete or "functionally complete" tear.
When assessing isometry during anterior cruciate ligament surgery, it is assumed that points determined to be isometric remain so after reconstruction. We sought to evaluate if isometric measurements vary with the status of the anterior cruciate ligament. A computerized electronic isometer was used to measure the magnitude and pattern of change in separation distance between a constant point in the tibial insertion of the anterior cruciate ligament and five positions within the femoral insertion with the anterior cruciate ligament intact, sectioned, and reconstructed. For the center position, the magnitude and pattern of the change in separation distance was physiologically isometric in all conditions (maximal length change, 3.0 mm). For the posterior position, the isometry pattern remained physiologic in each condition, and the magnitude of the separation distance was nearly isometric in all conditions (maximal length change, 3.7 mm). The superior and inferior positions had similar isometric measurements in the intact and sectioned conditions but significantly different measurements after anterior cruciate ligament reconstruction. Intraoperative assessment of isometry at positions in the center or posterior portion of the anterior cruciate ligament's femoral insertion provides useful information that is not altered by reconstruction. For superior and inferior positions, however, points found to be isometric in the anterior cruciate ligament-deficient knee did not remain isometric after reconstruction.