Björn Engström

The effect of weightbearing and external loading on anterior cruciate ligament strain

A force balance between the ligaments, articular contact, muscles and body weight maintains knee joint stability. Thus, it is important to study anterior cruciate ligament (ACL) biomechanics, in vivo, under weightbearing conditions. Our objective was to compare the ACL strain response under weightbearing and non-weightbearing conditions and in combination with three externally applied loadings: (1) anterior-posterior shear forces, (2) internal-external torques, and (3) varus-valgus moments. A strain transducer was implanted on the ACL of 11 subjects. All joint loadings were performed with the knee at 20 degrees of flexion. A significant increase in ACL strain was observed as the knee made the transition from non-weightbearing to weightbearing. During anterior shear loading, the strain values produced during weightbearing were greater than those of the non-weightbearing knee (shear loads <40N). At higher shear loads, the strain values became equal. During axial torsion, an internal torque of 10Nm strained the ACL when the knee was non-weightbearing while an equivalent external torque did not. Weightbearing significantly increased ACL strain values in comparison to non-weightbearing with the application of external torques and low internal torques (<3Nm). The strains became equal for higher internal torques. For V-V loading, the ACL was not strained in the non-weightbearing knee. However, weightbearing increased the ACL strain values over the range of moments tested. These data have important clinical ramifications in the development of rehabilitation protocols following ACL reconstruction since weightbearing has been previously thought to provide a protective mechanism to the healing graft.

Soccer injuries among elite female players

Injuries occurring in two female elite soccer teams were recorded during 1 year. Of 41 players, 33 (80%) sus tained 78 injuries. The incidence of injury during games was 24/1000 hours, while the incidence during training was 7/1000 hours. The majority (88%) of injuries were localized to the lower extremities, with equal occur rence in the left and right legs. Forty-nine percent of the injuries occurred in the knee or ankle. Most of the injuries were minor (49%), while 36% were moderate and 15% were major. Of the major injuries (N = 12), 10 were due to trauma and 7 (58%) were knee ligament or meniscal tears. Overuse injuries constituted 28% of all injuries and occurred mainly during preseason train ing and at the beginning and end of the competitive season. Traumatic injuries (72%) occurred mainly dur ing games with a predominance at the beginning of the competitive season. Almost 80% of the traumatic inju ries occurred during physical contact with an opponent. Extrinsic factors such as weather, playing surface, tem perature, or the position of the player within the team did not influence the injury rate. We conclude that female elite soccer players sustain a high incidence of injury. Few injuries were major, but 17% of the players sustained a major knee injury during the year.

Does a major knee injury definitely sideline an elite soccer player

Injuries occurring in three Swedish elite soccer teams were analyzed during 1 year. A total of 49 of 64 players (75%) sustained 85 injuries. The incidence of injury during games was 13 injuries per 1000 hours, while the incidence during training was 3 injuries per 1000 hours. Twenty percent of the injuries required hospital facili ties. The majority of the traumatic injuries (93%) were to the lower extremities, with one third of the total injuries occurring in the knee. Overuse injuries ac counted for 35% of all injuries and occurred mainly during preseason training and at the end of each sea son. Conversely, the majority of traumatic injuries oc curred during games, equally distributed between the first and second halves with a predominance toward the end of each half. The position of the player within the team did not influence injury rate. The referee considered 28% of the traumatic injuries to be caused by violation of existing rules. Thirty-four percent of the injuries were major, causing more than 1 month of absence from training and/or games. Eleven knee in juries required surgical intervention revealing seven rup tured ACLs, of which three were chronic. At followup, 9 to 18.5 months after injury, 4 of 12 players with major knee injuries had returned to play at the elite level. The others had either been transferred to lower divisions or were still in rehabilitation.

Assessment of functional knee bracing: an in vivo three-dimensional kinematic analysis of the anterior cruciate deficient knee.

OBJECTIVE To describe three-dimensional tibial and femoral movements in vivo and examine the effect of a brace on knee kinematics during moderate to intense activity. DESIGN Skeletal kinematics of anterior cruciate ligament deficient knees was measured with and without braces during moderate to intense activity. BACKGROUND Invasive markers implanted into the tibia and femur are the most accurate means to directly measure skeletal motion and may provide a more sensitive measure of the differences between brace conditions. METHODS Steinmann traction pins were implanted into the femur and tibia of four subjects having a partial or complete anterior cruciate ligament rupture. Non-braced and braced conditions were randomly assigned and subjects jumped for maximal horizontal distance to sufficiently stress the anterior cruciate ligament. RESULTS Intra-subject peak vertical force and posterior shear force were generally consistent between conditions. Intra-subject kinematics was repeatable but linear displacements between brace conditions were small. Differences in angular and linear skeletal motion were observed across subjects. Bracing the anterior cruciate ligament deficient knee resulted in only minor kinematic changes in tibiofemoral joint motion. CONCLUSION In this study, no consistent reductions in anterior tibial translations were observed as a function of the knee brace tested. Relevance. Investigations have reported that knee braces fail when high loads are encountered or when load is applied in an unpredictable manner. Questions remain regarding tibiofemoral joint motion, in particular linear displacements. The pin technique is a means for direct skeletal measurement and may provide a more sensitive measure of the differences between brace conditions.

The Influence of Functional Knee Bracing on the Anterior Cruciate Ligament Strain Biomechanics in Weightbearing and Nonweightbearing Knees

Functional knee braces are commonly prescribed after anterior cruciate ligament injury or reconstruction; however, their ability to protect the ligament, or graft, remains unclear. Our objective was to evaluate the anterior cruciate ligament strain response in braced and unbraced knees during weightbearing and nonweightbearing in combination with three externally applied loads: 1) anterior-posterior shear forces, 2) internal-external torques, and 3) varus-valgus moments. The Legend brace was tested. All external loads were applied to the tibia with the knee flexed to 20°. Reproducible data were obtained from 11 subjects. For anterior shear loads up to 130 N, the brace significantly reduced strain values compared with the unbraced knee during nonweightbearing and weightbearing conditions. For internal torques of the tibia (up to 9 N m), strain in the braced knee was significantly less than in the unbraced knee when the knee was nonweightbearing only. The brace did not reduce strain values when the knee was subjected to external torques (9 N m) or varus-valgus moments (10 N m) in weightbearing and nonweightbearing knees. These data indicate that a functional knee brace can protect the anterior cruciate ligament during anterior-posterior shear loading in the nonweightbearing and weightbearing knee and during internal torques in the nonweightbearing knee.

Shoulder function in patients with unoperated anterior shoulder instability

A functional analysis, including Rowe score and meas urements of isokinetic peak torque and range of motion of the shoulder, and a subjective assessment were performed in 26 consecutive patients (23 males and 3 females) with unoperated anterior shoulder instability. Patients experienced the initial dislocation at an av erage age of 23 ± 8 years and 58% occurred during sports activity. No patient had gone through any con trolled rehabilitation program. In this study, an average of 7 years (range, 1 to 28) had passed since the initial dislocation. Fifty-nine percent of the patients com plained of markedly reduced ability to perform in sports because of instability, impaired strength, decreased range of motion, and pain induced by activity. The majority (65%) of the patients reported instability only during physical activity. The average Rowe score was 68 ± 14 on a scale of 100. In comparison with the healthy side, the injured shoulder had a significantly lower isokinetic peak torque during abduction and in ternal rotation, as well as a reduced range of motion in extension, abduction, and external rotation, but not in flexion. The severity of impairment (Rowe score, deficit in range of motion, and peak torque) was not related to the number of dislocations sustained or to the du ration of instability.

Five-year results of anterior cruciate ligament reconstruction with the Stryker Dacron high-strength ligament

Forty-two consecutive patients (27 male and 15 female, with a mean age of 26 years) suffering from uniflateral chronic anterior cruciate ligament insufficiency underwent surgical reconstruction with a Dacron highstrength ligament (Stryker). In 32 patients the synthetic legament was used as a reinforcement in an iliotibial band intra-articular procedure and in 10 patients as an intra-articular prosthesis without biological reinforcement. There were 24 concomitant injuries such as meniscal tears, status post—meniscectomy or medial collateral ligament insufficiency at the time of reconstruction. The initial injury occurred during soccer in 23 patients and other pivoting sports in 16 patients. Two and 5 years after reconstruction, the patients underwent clinical examination, including the instrumented knee laxity test (OSI), and performed subjective evaluation. The anterior tibial translation was 6.3±2.6mm grater than in the healthy knee, the mean Lysholm score was 78 points, and the Tegner activity score was lower than its pre-injury level. Radiography revealed that 31 of 37 ligaments had ruptured and another 2 ligaments showed more than 5 mm side-to-side increased laxity. The Stryker Dacron high-strength ligament ruptured in more than 80% of the cases and patients could not return to their pre-injury physical performance activities.

How can injuries be prevented in the World Cup soccer athlete

In order to prevent soccer injuries, different risk factors have to be identified as intrinsic (e.g., joint stability or muscle imbalance) and extrinsic (e.g., equipment, turf, and rules risk factors). Some preventive measures are discussed in this article, such as shin guards, prophylactic braces and taping (or both), and proprioceptive training.

A comparison of 50, 100 and 200 mg of intra-articular pethidine during knee joint surgery, a controlled study with evidence for local demethylation to norpethidine.

Pethidine (meperidine) is a compound with both local anaesthetic and opioid agonist properties. We have in a recent study demonstrated that pethidine could be an interesting alternative to prilocaine in arthroscopy with local anaesthetic technique. Therefore, we investigated, in a controlled randomized double-blind study, the effect of three doses of pethidine compared with a standard local anaesthetic, in patients subjected to arthroscopic knee joint surgery. Ten patients in each group received 50 mg (P50), 100 mg (P100), 200 mg (P200) of pethidine or prilocaine (5 mg/ml) + adrenaline (4 mg/ml) (PC), injected intra-articularly (i.a.) before surgery. We measured pain intensity and discomfort during arthroscopy and pain intensity at rest and at movement, nausea and tiredness for 3 days post-operatively at regular intervals using the VAS-technique. We also measured the concentration of pethidine and its demethylated metabolite, norpethidine, in plasma by collecting blood samples at 20, 40, 60, 80, 140 and 200 min following injection, and in synovial fluid which was collected through the arthroscope at the start and the end of the surgery. It was found that significantly more patients in the P50 group (n = 6) needed general anaesthesia due to intense pain than those in the P100 group (n = 1), P200 group (n = 0) or the PC group (n = 1). The PC group required significantly more analgesics and had a significantly higher calculated total sum of pain scores at movement post-operatively, than the other three groups. The P200 group more often reported tiredness post-operatively than the other three groups. We conclude that 100 or 200 mg pethidine i.a. produces satisfactory anaesthesia for surgery. There was a rapid transfer of pethidine from synovial fluid to plasma, resulting in plasma levels earlier reported to produce centrally mediated effects, such as analgesia and tiredness. We found much higher concentrations of norpethidine in the synovial fluid than in plasma, suggesting a local demethylation in the knee joint tissues. This site of drug oxidation has not earlier been demonstrated neither in vitro nor in vivo. The results suggest that pethidine given i.a. in the dose range of 50 to 200 mg results in analgesia due to both peripheral and central mechanisms. The significant systemic uptake of pethidine can cause unwanted side-effects.

Local anesthesia for arthroscopic surgery of the ankle using pethidine or prilocaine.

Investigation of the intraoperative and postoperative pain-reducing effect of pethidine (meperidine) as compared with local anesthetics given into the ankle joint was performed, in a comparative and double-blind fashion, in 20 patients subjected to arthroscopy of the ankle, diagnostic and surgical procedures. These patients were randomly assigned to one of two groups. Group A consisted of 10 patients receiving prilocaine 5% with adrenaline and the patients of group B received pethidine 5% with adrenaline intraarticularly. During arthroscopy, the patients reported on pain and discomfort using visual analog scales. Ratings did not differ between the two groups, but six patients would not have chosen the local anesthetic technique again. Postoperatively, all patients rated their pain and discomfort at rest and at movement (1, 2, 3, 5, 6, 8, and 24 hours and at three times during 2 following days). No differences were found between the two groups, except for pain at rest through the whole observation period when significant lower values for pethidine. There were no differences in use of analgesics between the two groups. The current study indicates that pethidine is a potential alternative to prilocaine in arthroscopy of the ankle.