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Biomedical subjects

Louis C Almekinders

Publications and source records attributed to Louis C Almekinders.

11 recordsLinked to original sources
PubMed2004

Strain behavior of the distal achilles tendon: implications for insertional achilles tendinopathy.

BACKGROUND: The changes associated with Achilles insertional tendinopathy (AIT) are seen in the anterior portion of the Achilles tendon near its calcaneal insertion. Strain behavior of this portion of the tendon was evaluated. HYPOTHESIS: The highest strains are in the anterior portion of the tendon. STUDY DESIGN: Controlled laboratory study. METHODS: Six cadaveric legs were tested. While moving through a functional range of ankle motion, strains in five different regions of the tendon insertion were tested. First, the load on the tendon was increased from 30 to 170 N in the starting, plantar flexed position. Then, the ankle was moved from a plantar flexed position into dorsiflexion. RESULTS: Strains in the posterior sites increased significantly (P < 0.001) as the movement into dorsiflexion occurred. This was significantly (P < 0.01) different than the anterior sites, which showed a trend toward decreasing strain. CONCLUSIONS: Although the anterior portion of the Achilles tendon is generally affected in AIT, relative strain shielding is seen in this portion of the tendon. These findings suggest that the role of repetitive tensile loads in the causation of AIT is more complex than often described. CLINICAL RELEVANCE: These findings may explain the variable therapeutic response following measures aimed at decreasing tensile loads on the tendon.

Achilles Tendon↗
PubMed2004

Nonsteroidal anti-inflammatory drugs and acetaminophen in the treatment of an acute muscle injury.

BACKGROUND: Nonsteroidal anti-inflammatory drugs are frequently used to treat muscle injuries in athletes. It is not known whether the anti-inflammatory effects of these drugs are important or whether their effectiveness is a result of their central analgesic effect. HYPOTHESIS: The effects of nonsteroidal anti-inflammatory drugs are no different than the effects of an analgesic (acetaminophen) without anti-inflammatory action in an experimental, acute muscle contusion model. STUDY DESIGN: Controlled animal study. METHODS: A standardized, unilateral, nonpenetrating injury was created to the tibialis anterior muscle of 96 adult male mice. Four treatment groups were used: group 1, placebo treatment; group 2, treatment with rofecoxib, a nonsteroidal anti-inflammatory drug with cyclooxygenase-2 selectivity, and treatment after the injury; group 3, rofecoxib treatment starting 24 hours before the injury; and group 4, acetaminophen treatment after the injury. The muscle and the contralateral normal muscle were evaluated at 2, 5, and 7 days after injury by grading of gait, wet weight as a measure of edema, and histologic evaluation. RESULTS: Group 1 had significantly more gait disturbances at day 2 than all other groups (P < .05). No differences were found at days 5 and 7. Wet weights showed an increase at day 2 in group 1 (P < .01). Again, no differences were found at days 5 and 7. Histology revealed similar inflammatory changes at day 2 in all groups, with regeneration of muscle fibers at days 5 and 7. CONCLUSIONS: The results indicate that rofecoxib as a nonsteroidal anti-inflammatory drug and acetaminophen as a non-nonsteroidal anti-inflammatory drug analgesic have similar effects. The lack of differences in wet weights and histology suggests that the anti-inflammatory effects of rofecoxib are not an important feature of its action. CLINICAL RELEVANCE: The routine use of nonsteroidal anti-inflammatory drugs in muscle injuries may need to be critically evaluated because low-cost and low-risk analgesics may be just as effective.

Acetaminophen↗
PubMed2004

Knee stability following anterior cruciate ligament rupture and surgery. The contribution of irreducible tibial subluxation.

BACKGROUND: Knee stability after anterior cruciate ligament reconstruction is generally determined by measuring total anteroposterior tibial motion. In spite of a decrease in excessive anteroposterior tibial motion after anterior cruciate ligament reconstruction, problems can still develop. In the present study, we sought to define the tibiofemoral relationship more accurately with use of stress radiographs of human knees after anterior cruciate ligament rupture and after anterior cruciate ligament reconstruction. METHODS: A previously described radiographic technique was used to evaluate the position of the tibia relative to the femur with the application of an anteriorly directed tibial force and subsequently with the application of a posteriorly directed tibial force. Tibial position and total tibial translation were calculated from these radiographs. In addition, KT-1000 measurements were obtained. Three groups of patients were studied: Group 1 included twenty-eight patients with an untreated anterior cruciate ligament rupture, Group 2 included nineteen patients who had undergone a clinically successful anterior cruciate ligament reconstruction, and Group 3 included twenty-five control subjects with normal knees. RESULTS: KT-1000 testing showed that the average side-to-side differences in Group 1 (5.8 mm) and Group 2 (2.7 mm) were significantly different from that in Group 3 (0.8 mm) (p < 0.01 and p < 0.05, respectively). Stress radiographs showed that the average total tibial translation in Group 1 (9.8 mm) was significantly different from those in Group 2 (5.6 mm) and Group 3 (4.3 mm) (p < 0.05 and p < 0.001, respectively). Within Group 1, knees with radiographic signs of osteoarthritis were more stable, with an average total tibial excursion of 6.8 mm. The improved stability of the reconstructed knees in Group 2 and the osteoarthritic knees in Group 1 was not entirely the result of decreased anterior tibial translation; it was, in part, due to an irreducible anterior subluxation of the tibia. A posteriorly directed stress in these knees did not reduce the tibia to the anatomic position relative to the femur; the osteoarthritic knees in Group 1 were 9.9 mm short of full reduction and the knees in Group 2 were 3.1 mm short of full reduction (p < 0.01) CONCLUSIONS: Irreducible tibial subluxation can be present in the knee following surgical reconstruction of the anterior cruciate ligament. Osteoarthritic changes following an untreated anterior cruciate ligament rupture are also associated with uncorrectable tibial subluxation along with a decrease in instability. The irreducible tibial subluxation could explain why osteoarthritic changes still may develop in stable, reconstructed knees in spite of the improved stability. Currently used arthrometric measurements, such as KT-1000 scores, do not measure this phenomenon.

Adult↗
PubMed2004

Biomechanics and pathophysiology of overuse tendon injuries: ideas on insertional tendinopathy.

Tendons behave viscoelastically and exhibit adaptive responses to conditions of increased loading and disuse. High-resolution, real-time ultrasound scanning confirms the applicability of these findings in human tendons in vivo. In addition, recent biomechanical studies indicate that strain patterns in tendons may not be uniform, as tendons show stress-shielded areas and areas subjected to compressive loading at the enthesis. These areas correspond to the sites where tendinopathic characteristics are typically seen. This indicates that some tendinopathies may, paradoxically, be considered as 'underuse' lesions despite the common beliefs that they are overuse injuries. Classic inflammatory changes are not frequently seen in chronic athletic tendon conditions and histopathology features in tendinopathic tendons are clearly different from normal tendons, showing an exaggerated dysfunctional repair response. Tendinopathies are traditionally considered overuse injuries, involving excessive tensile loading and subsequent breakdown of the loaded tendon. Biomechanical studies show that the strains within the tendons near their insertion site are not uniform. If the material properties are similar throughout the tendon, forces transferred through the insertion site preferentially load the side of the tendon that is usually not affected initially in tendinopathy. In that case, the side affected by tendinopathy is generally 'stress shielded'. Thus, the presence of differential strains opens the possibility of alternative biomechanical explanations for the pathology found in these regions of the tendon. The traditional concept of tensile failure may not be the essential feature of the pathomechanics of insertional tendinopathy. Certain joint positions are more likely to stress the area of the tendon commonly affected by tendinopathy. Incorporating different joint position exercises may exert more controlled stresses on these affected areas of the tendon, possibly allowing better maintenance of the mechanical strength of that tendon region and, therefore, prevent injury. Such exercises could stress a healing area of the tendon in a controlled manner and thus stimulate healing once an injury has occurred. Additional work is needed to prove whether such principles should be incorporated in current rehabilitation techniques.

Aging↗
PubMed2004

Minimally invasive subcutaneous fasciotomy for chronic exertional compartment syndrome of the lower extremity.

Chronic exertional compartment syndrome of the lower extremity can be debilitating in the active population. Open fasciotomy typically provides a cure or significant improvement in up to 90% of patients, provided that the compartments are adequately released. Cosmetic deformity from the surgery may be a major concern, especially in the young female athlete. A technique for minimally invasive subcutaneous fasciotomy is described that allows adequate compartment release and a favorable cosmetic result.

Chronic Disease↗
PubMed2003

Types and epidemiology of tendinopathy.

During the last few decades, the role of sports and physical activity has become more and more important in all modern communities. The risk of tendon injury has thus increased, and prevention has become important. Epidemiologic studies are important when planning prevention programs for tendon injuries. Because of individual sport cultures and different sport habits in different countries, national epidemiologic studies are of importance in each individual country.

Achilles Tendon↗
PubMed2003

Compression etiology in tendinopathy.

Recent studies have emphasized that the etiology of tendinopathy is not as simple as was once thought. The etiology is likely to be multifactorial. Etiologic factors may include some of the traditional factors such as overuse, inflexibility, and equipment problems; however, other factors need to be considered as well, such as age-related tendon degeneration and biomechanical considerations as outlined in this article. More research is needed to determine the significance of stress-shielding and compression in tendinopathy. If they are confirmed to play a role, this finding may significantly alter our approach in both prevention and in treatment through exercise therapy. The current biomechanical studies indicate that certain joint positions are more likely to place tensile stress on the area of the tendon commonly affected by tendinopathy. These joint positions seem to be different than the traditional positions for stretching exercises used for prevention and rehabilitation of tendinopathic conditions. Incorporation of different joint positions during stretching exercises may exert more uniform, controlled tensile stress on these affected areas of the tendon and avoid stresshielding. These exercises may be able to better maintain the mechanical strength of that region of the tendon and thereby avoid injury. Alternatively, they could more uniformly stress a healing area of the tendon in a controlled manner, and thereby stimulate healing once an injury has occurred. Additional work will have to prove if a change in rehabilitation exercises is more efficacious that current techniques.

Athletic Injuries↗
PubMed2002

Achilles rupture in the athlete. Current science and treatment.

Achilles tendon ruptures became increasingly common in the latter half of the 20th century. Once the diagnosis is made, the patient's goals and objectives should be clearly stated. The treatment choice should incorporate the patient's needs, desires, objectives, and functional goals to assure an optimal result.

Achilles Tendon↗
PubMed2001

Strain patterns in the patellar tendon and the implications for patellar tendinopathy.

This study investigated the strain pattern in human patellar tendon in an area of the tendon where changes commonly associated with patellar tendinitis are found. Eight fresh frozen human knees were instrumented with strain gauges on both the anterior and posterior side of the proximal patellar tendon. Both static and dynamic measurements were carried out in a range from 0 degrees to 60 degrees of flexion. We found uniform tensile strain in the tendon with the knee in full extension. However, as the knee was brought into flexion, the tensile strain increased on the anterior side but decreased on the posterior side in the central, proximal location of the tendon. The posterior side of the proximal patellar tendon is most commonly affected in patellar tendinopathy. This study indicates that this area of the tendon may not subjected to the highest tensile loads in the functional flexion range. It is possible that stress shielding is more important etiological factor in insertional tendinopathy as opposed to repetitive tensile loads.

Aged↗
PubMedDate not supplied

Intramedullary screw fixation of Jones fractures. Analysis of failure.

Treatment failures after screw fixation of Jones fractures are reported to be infrequent. Between 1993 and 1999, 15 patients (mean age, 21.7 years) underwent cannulated screw fixation of a Jones fracture at our institution. There were six treatment failures: four refractures and two symptomatic nonunions. The mean time to full activity was 6.8 weeks for the patients with failure compared with 9 weeks for patients who did not have complications. Although all patients were asymptomatic and radiographically progressing to union before return to full activity, only one of six patients with failures had complete radiographic union, compared with six of seven patients with no complications. There was a higher proportion of elite athletes (division I or professional level) among the failure group (83%) compared with those without complications (11%). There were no significant differences in age, sex, screw diameter, use of bone graft, or age of fracture between patients with failures and those without complications. Return to full activity, especially among elite athletes, before complete radiographic union was predictive of failure. Even though intramedullary screw fixation offers advantages over nonoperative treatment, a significant risk of postoperative complications exists.

Adolescent↗