Early versus late start of open kinetic chain quadriceps exercises after ACL reconstruction with patellar tendon or hamstring grafts: a prospective randomized outcome study

The purpose of the present investigation was to evaluate physical outcome after anterior cruciate ligament (ACL) reconstruction with early versus late initiation of open kinetic chain (OKC) exercises for the quadriceps in patients operated on either patellar tendon or hamstring grafts. Sixty-eight patients, 36 males and 32 females, with either patellar tendon graft (34 patients) or hamstring graft (34 patients) were enrolled in this study. All patients were randomly allocated to either early (the 4th postoperative week) or late (the 12th postoperative week) start of OKC exercises for the quadriceps, resulting in four subgroups: patellar tendon reconstruction, early start (P4) or late start (P12) of OKC quadriceps exercises, hamstring tendon reconstruction, early start (H4) or late start (H12) of quadriceps OKC exercises. Prior to surgery and 3, 5 and 7 months later, assessments of range of motion (goniometer), anterior knee laxity (KT-1000), postural sway (KAT 2000), thigh muscle torques (Kin–Com dynamometer) and anterior knee pain (anterior knee pain score) were evaluated. No significant group differences were found in terms of range of motion 3, 5 and 7 months postoperatively. The H4 group showed a significantly higher mean difference of laxity over time of 1.0 mm (CI: 0.18–1.86) than the P4 group (P = 0.04). Within the same type of surgery, the H4 against the H12, the mean difference over time was 1.2 mm (0.37–2.1) higher in the H4 group than in the H12 group (P = 0.01). There were no significant group differences in terms of postural sway or anterior knee pain at the different test occasions. Significant differences in trends (changes over time) were found when comparing the four groups, for both quadriceps muscle torques (P < 0.001) and hamstring muscle torques (P < 0.001). All groups, except the P4 group, reached preoperative values of quadriceps muscle torques at the 7 months follow-up. In the H4 and the H12 groups, significantly lower hamstring muscle torques at the 7 months follow-up compared with preoperative values were found. In conclusion, early start of OKC quadriceps exercises after hamstring ACL reconstruction resulted in significantly increased anterior knee laxity in comparison with both late start and with early and late start after bone–patellar tendon–bone ACL reconstruction. Furthermore, the early introduction of OKC exercises for quadriceps did not influence quadriceps muscle torques neither in patients operated on patellar tendon nor hamstring tendon grafts. On the contrary, it appears as if the choice of graft affected the strength of the specific muscle more than the type of exercises performed. Our results could not determine the appropriate time for starting OKC quadriceps exercises for patients who have undergone ACL reconstruction with hamstring tendon graft. Future studies of long-term results of anterior knee laxity and functional outcome are needed.     

Effects of open versus closed kinetic chain training on knee laxity in the early period after anterior cruciate ligament reconstruction

Knee extensor resistance training using open kinetic chain (OKC) exercise for patients recovering from anterior cruciate ligament reconstruction (ACLR) surgery has lost favour mainly because of research indicating that OKC exercise causes greater ACL strain than closed kinetic chain (CKC) exercise. In this prospective, randomized clinical trial the effects of these two regimes on knee laxity were compared in the early period after ACLR surgery. Thirty-six patients recovering from ACLR surgery (29 males, 7 females; age mean = 30) were tested at 2 and 6 weeks after ACLR with knee laxity measured using the Knee Signature System arthrometer. Between tests subjects trained using either OKC or CKC resistance of their knee and hip extensors in formal physical therapy sessions three times per week. Following adjustment for site of treatment, pretraining injured knee laxity, and untreated knee laxity at post-training, the use of OKC exercise, when compared to CKC exercise, was found to lead to a 9% increase in looseness with a 95% confidence interval of -8% to +29%. These results indicate that the great concern about the safety of OKC knee extensor training in the early period after ACLR surgery may not be well founded.     

Comparison of anterior cruciate ligament reconstruction in male and female athletes using the patellar tendon and hamstring autografts

Despite the higher incidence of anterior cruciate ligament (ACL) injuries in female than in male athletes few authors have studied the effects of gender on the outcome of ACL reconstruction. This prospective study compared the results of ACL reconstruction using the patellar tendon and hamstring techniques in men and women. We prospectively followed 80 comparable athletes (46 males, 32 females) from a population of 287 patients operated on at our institution for ACL reconstruction using either patellar tendon or hamstring graft. There were 26 males and 14 females in the patellar tendon group, and 22 males and 18 females in the hamstring group. All patients were operated on by the same surgeon within 6 months from injury and underwent the same rehabilitation program at the same center. After an average of 36 months the patients were assessed by clinical evaluation, computerized knee laxity analysis, and isokinetic and functional strength tests; standard knee scores were also used. Among patellar tendon patients there were no significant differences between males and females regarding knee evaluation form, laxity, or isokinetic and functional tests. Females in the hamstring group had significantly greater laxity, and isokinetic tests at 1 year revealed a significantly higher deficit of peak torque at 60°/s in flexion and extension. We suggest further studies on the clinical significance of these findings particularly on their possible ramifications in the areas of return to sports and rehabilitation of female athletes     

Early post-operative morbidity following anterior cruciate ligament reconstruction: patellar tendon versus hamstring graft

This study documented postoperative morbidity during the first 4 months following anterior cruciate ligament (ACL) reconstruction using either patellar tendon or hamstring tendon autograft. Sixty-five patients undergoing primary arthroscopically assisted single-incision ACL reconstruction were randomized to have a central third bone patellar tendon bone autograft (PT) or a doubled semitendinosus/doubled gracilis autograft (HS). Postoperatively patients undertook a standard 'accelerated' rehabilitation protocol. Patients were reviewed after 2 weeks, 8 weeks, and 4 months. At each review the location and severity of general knee pain and the presence and severity of anterior knee pain (AKP) were recorded as were the presence and size of an effusion as well as the active and passive flexion and passive extension deficits compared to the contralateral limb. Pain on kneeling, KT-1000 measured side to side difference in anterior tibial displacement, isokinetic assessment of quadriceps and hamstring peak torque deficits, IKDC score and Cincinnati sports activity level were also recorded after 4 months. After 2 weeks more patients in the PT group complained of AKP and reported that the pain was more severe. After 8 weeks there was no significant difference between the groups for any variable. After 4 months the severity of general pain experienced and the incidence of pain on kneeling were greater in the PT group. The PT group also demonstrated a significantly greater quadriceps peak torque deficit at 240 degrees /s. IKDC scores were higher in the HS group, but Cincinnati sports activity scores were higher in the PT group. Although we observed a lower morbidity in the HS group, primarily related to pain, the severity of pain in both groups was relatively low and, in light of the higher mean sports activity level observed in the PT group at 4 months the clinical impact of the difference may not be significant.     

Knee extensors kinetic chain training in anterior cruciate ligament deficiency

Open kinetic chain (OKC) knee extensor resistance training has lost favour in rehabilitation of patients with knee ACLD due to concerns that this exercise is harmful to the remaining portion of the ACL and its secondary stabilizers, and will be less effective in improving function. In this randomized, single-blind clinical trial, closed and OKC knee extensor training were compared for their effects on knee laxity and function in patients with ACLD knees. Sixty-four patients with a diagnosis of knee ACLD (49 M, 15 F; mean age=30 years) were measured for knee laxity, using a ligament arthrometer, and function with the Hughston Clinic knee self-assessment questionnaire and maximal effort single leg jump testing. Between the above tests and identical tests carried out 6 weeks later, subjects trained using either open or closed kinetic chain resistance of their knee and hip extensors as part of formal physical therapy sessions three times per week for 6 weeks. The groups exhibited no statistically significant differences (p<0.083) in outcome. These results indicate that knee extensor OKC training, as used in this study, can be safely applied to patients with knee ACL deficiency, and shows no superiority to CKC training.     

Anterior cruciate ligament reconstruction with doubled semitendinosus and gracilis tendon graft in rugby players

The purpose of this study was to evaluate prospectively the results of anterior cruciate ligament (ACL) reconstruction with doubled hamstring tendon graft in a selected group of 18 rugby players. The graft was fixed with a transcondylar screw (Transfix) on the femur, and with an absorbable interference screw and a metallic staple on the tibia. All the patients followed the same rehabilitation program. Return to sports activities was allowed after 6 months. Follow-up was 2 years in all cases. The athletic level of the patients was rated according to the Tegner scoring system. Clinical results were evaluated using the International Knee Documentation Committee (IKDC) scoring system. Furthermore, an instrumented evaluation of the anterior laxity with a KT–1000 arthrometer, and an isokinetic evaluation were performed 6 and 24 months after surgery. The Tegner mean score at follow-up (8.2) was similar to that prior to injury (8.3). IKDC overall results were normal in ten cases (55.6%), nearly normal in six cases (33.3%), and abnormal in two cases (11.1%). Side-to-side difference of anterior laxity measured with KT–1000 at 6 and 24 months did not show an impairment of knee stability with time. Isokinetic evaluation showed a significant improvement on peak torque both in extension and flexion on comparison between 6- and 24-month measurements. The results reported in this study showed that the use of doubled hamstring tendon graft for ACL reconstruction in athletes that were at risk for high-energy traumas to the knees, such as rugby players, gave normal or nearly normal results in about 90% of the cases. Recovery of muscle strength was almost complete 2 years after surgery, and there was no impairment of knee stability with time.     

Randomized prospective study of ACL reconstruction with interference screw fixation in patellar tendon autografts versus femoral metal plate suspension and tibial post fixation in hamstring tendon autografts: 5-year clinical and radiological follow-up results

Patellar tendon graft has been the most frequently used material in anterior cruciate ligament (ACL) reconstruction, but the hamstring tendons have been increasingly used as well; however, which graft is to be preferred is not adequately supported by existing clinical studies. In this prospective randomized clinical trial, the study hypothesis was that the hamstring tendons are equally good graft material as the patellar tendon in ACL reconstruction. Ninety-nine patients with laxity due to a torn ACL underwent arthroscopically assisted reconstruction with graft randomization according to their birth year to either patellar tendon with metal interference screw fixation or double looped semitendinosus and gracilis tendons with fixation similar to the Endobutton technique using a titanium metal plate suspension proximally and screw-washer postdistally. Excluding preoperative Lysholm knee score, there were no significant differences between the two groups in the preoperative and operative data. A standard rehabilitation regimen was used for all the patients, including immediate postoperative mobilization without a knee brace, protected weight bearing for 2 weeks, and return to full activity at 6–12 months postoperatively. Forty patients in the patellar tendon group and 39 patients in the hamstring tendon group were available for clinical evaluation at median 5 years after surgery (ranges 3 years 11 months–6 years 7 months). The results revealed no statistically significant differences with respect to clinical and instrumented laxity testing, isokinetic muscle torque measurements, International Knee Documentation Committee ratings, Lysholm (knee score), Tegner (activity level) and Kujala patellofemoral knee scores. There was an enlargement of the drill tunnels, statistically more in the hamstring tendon group, but no increase from 2 to 5 years in either group. Narrowing of the joint spaces (IKDC measurement method) from 2 to 5 years postoperatively was seen in both the groups, however, without difference between the two groups.     

A 2-year follow-up of rehabilitation after ACL reconstruction using patellar tendon or hamstring tendon grafts: a prospective randomised outcome study

Sixty-eight patients were clinically evaluated preoperatively, 3, 5, 7, 9 months, 1 and 2 years after ACL reconstruction, 34 with patellar tendon graft, 34 with hamstring graft. Outcome regarding graft choice and anterior knee laxity (P = 0.04) was in favour of patellar tendon graft. Hamstring graft led to a larger laxity, 2.4 mm compared with patellar tendon graft, 1.3 mm at 1 year and 2.5 mm and 1.5 mm, respectively, at 2 years (P = 0.05). There was a significant difference in rotational knee stability in favour of the patellar tendon graft at all test occasions but 9 months. A general effect regarding graft choice and muscle torque was found at 90°/s for quadriceps (P = 0.03) and hamstrings (P ≤ 0.0001) and at 230°/s for hamstrings (P ≤ 0.0001). No treatment effect regarding graft choice and one-leg hop test, postural sway or knee function was found. No group differences in anterior knee pain were found at any of the test occasions but 2 years in favour of hamstring graft compared to patellar tendon graft (P = 0.04). Patellar tendon graft resulted in higher activity level than hamstring graft at all test occasions but 1 year (P = 0.01). Patellar tendon ACL reconstruction led to more stable knees with less anterior knee laxity and less rotational instability than hamstring ACL reconstruction. Hamstring graft patients had not reached preoperative level in hamstring torque even 2 years after ACL reconstruction. Athletes with patellar tendon graft returned to sports earlier and at a higher level than those with hamstring graft.     

Effects of closed versus open kinetic chain knee extensor resistance training on knee laxity and leg function in patients during the 8- to 14-week post-operative period after anterior cruciate ligament reconstruction

Open kinetic chain (OKC) knee extensor resistance training has lost favour in ACLR rehabilitation due to concerns that this exercise is harmful to the graft and will be less effective in improving function. In this randomized, single-blind clinical trial OKC and closed kinetic chain (CKC) knee extensor training were compared for their effects on knee laxity and function in the middle period of ACLR rehabilitation. The study subjects were 49 patients recovering from ACLR surgery (37 M, 12 F; mean age=33 years). Tests were carried out at 8 and 14 weeks after ACLR with knee laxity measured using a ligament arthrometer and function with the Hughston Clinic knee self-assessment questionnaire and single leg, maximal effort jump testing (post-test only). Between tests, subjects trained using either OKC or CKC resistance of their knee and hip extensors as part of formal physical therapy sessions three times per week. No statistically significant (one-way ANOVA, p>0.05) differences were found between the treatment groups in knee laxity or leg function. OKC and CKC knee extensor training in the middle period of rehabilitation after ACLR surgery do not differ in their effects on knee laxity or leg function. Exercise dosages are described in this study and further research is required to assess whether the findings in this study are dosage specific.     

应用等速肌力测试评价膝前交叉韧带断裂重建术后康复的效果

目的:采用等速肌力测试系统测试前交叉韧带(ACL)断裂患者在重建术前、术后的肌肉力量,评价有、无严格的康复训练计划对患者康复效果的影响。方法:采用美国产Biodex System 3多关节等速肌力测试系统,以60°/s、120°/s两种速度测定67例膝关节前交叉韧带断裂及韧带重建术后6个月、12个月患者的股四头肌和腘绳肌肌力,包括峰力矩(PT)、峰力矩/体重比值(PT/BW)、总功(TW)、平均峰力矩(AVG PT)。将其中遵医嘱进行康复训练的24人作为康复训练组,另外无严格康复训练计划、自主活动的43人作为未康复训练组。结果:手术前患膝屈、伸肌群的PT、PT/BW、TW、AVG PT较健侧均显著降低;ACL重建术后6个月、12个月,两组患者股四头肌和腘绳肌肌力均较术前有所提高,其中未康复训练组患侧股四头肌肌力恢复至健侧70%左右,腘绳肌肌力恢复至健侧75%,康复训练组股四头肌和腘绳肌肌力分别恢复至健侧的80%和85%左右,高于未康复训练组,但与健侧相比仍有差距。结论:康复训练对ACL重建术后股四头肌和腘绳肌的肌力恢复有明显的作用。等速肌力测试是评价前交叉韧带重建术后康复效果的有效手段。     

Muscle strength evaluations after ACL reconstruction

The quadriceps and hamstring muscle strengths of 16 patients operated using a bone-patellar tendon-bone (BTB) autograft and 32 patients operated using a quadruple hamstring autograft for an arthroscopic anterior cruciate ligament (ACL) reconstruction were analyzed 4- to 7-years postoperatively. Standardized isokinetic testing, a clinical evaluation and instrumented assessment of knee laxity were done. The findings showed no significant strength deficits between the patients in the BTB and Hamstring groups and the deficits were, in general, small. The quadriceps and hamstring muscle strengths were better in patients with a longer than shorter follow-up and stable knees had less knee flexion torque deficit than unstable knees. Strength deficit was associated with lower Lysholm knee scores. The findings of this study showed that the muscle strengths of the operated limb had a positive association with the functional outcome of the knee in the long-term and support the use of active rehabilitation after ACL reconstruction.     

Range of motion training in brace vs. plaster immobilization after anterior cruciate ligament reconstruction: a prospective randomized comparison with a 2-year follow-up

The purpose of this prospective and randomized study was to compare rehabilitation with early range of motion (ROM) training vs immobilization following anterior cruciate ligament (ACL) reconstruction. Fifty patients, undergoing an ACL reconstruction with a bone-patellar tendon-bone graft, were postoperatively allocated randomly to either a plaster cast or a brace for 5 weeks. The brace group had ROM exercises from postoperative day 7. The commencement of ROM exercises was postponed 4 weeks for the plaster group compared to the brace group, but progressed subsequently with equal speed. There was no difference between the groups in the ROM of flexion or extension 20 weeks after the ACL reconstruction and later. Twenty-four months after surgery, the muscle strength deficit in the hamstring muscles (isokinetic measurements; percent difference, injured vs uninjured) was significantly larger in the brace group (mean +/- SD: 5.9 +/- 7.8%, P < 0.01) than in the plaster group (- 0.9 +/- 11.8%, NS) (brace vs plaster group, P < 0.05). Furthermore, there was also a tendency in the brace group to a larger strength deficit in the quadriceps muscle (brace: 11.1 +/- 13.2%, P < 0.001; plaster: 3.8 +/- 12.9%, NS) (brace vs plaster group, P= 0.07). There was no difference between the groups in the total sagittal knee laxity, as measured with an arthrometer, or in the subjective knee function or activity level (Lysholm score together with the Tegner activity level) between the groups. It is concluded that the postoperative treatment with early range of motion training after ACL reconstruction gave as good ROM, knee stability, subjective knee function and activity level as the treatment with immobilization. It is hypothesized that the larger strength deficit observed after rehabilitation with early range of motion training is secondary to the more intensive training and physical therapist involvement that was demanded in order to achieve full ROM following immobilization.     

Knee extension and flexion muscle power after anterior cruciate ligament reconstruction with patellar tendon graft or hamstring tendons graft: a cross-sectional comparison 3 years post surgery

Hamstring muscles play a major role in knee-joint stabilization after anterior cruciate ligament (ACL) injury. Weakness of the knee extensors after ACL reconstruction with patellar tendon (PT) graft, and in the knee flexors after reconstruction with hamstring tendons (HT) graft has been observed up to 2 years post surgery, but not later. In these studies, isokinetic muscle torque was used. However, muscle power has been suggested to be a more sensitive and sport-specific measures of strength. The aim was to study quadriceps and hamstring muscle power in patients with ACL injury treated with surgical reconstruction with PT or HT grafts at a mean of 3 years after surgery. Twenty subjects with PT and 16 subjects with HT grafts (mean age at follow up 30 years, range 20–39, 25% women), who were all included in a prospective study and followed the same goal-based rehabilitation protocol for at least 4 months, were assessed with reliable, valid, and responsive tests of quadriceps and hamstring muscle power at 3 years (SD 0.9, range 2–5) after surgery. The mean difference between legs (injured minus uninjured), the hamstring to quadriceps (H:Q, hamstring divided by quadriceps) ratio, and the limb symmetry index (LSI, injured leg divided by uninjured and multiplied by 100) value, were used for comparisons between the groups (analysis of variance). The mean difference between the injured and uninjured legs was greater in the HT than in the PT group for knee flexion power (–21.3 vs. 7.7 W, p = 0.001). Patients with HT graft had lower H:Q ratio in the injured leg than the patients with PT graft (0.63 vs. 0.77, p = 0.012). They also had lower LSI for knee flexion power than those in the PT group (88 vs. 106%, p < 0.001). No differences were found between the groups for knee extension power. The lower hamstring muscle power, and the lower hamstring to quadriceps ratio in the HT graft group than in the PT graft group 3 years (range 2–5) after ACL reconstruction, reflect imbalance of knee muscles after reconstruction with HT graft that may have a negative effect on dynamic knee-joint stabilization.     

Two-year outcomes following ACL reconstruction with allograft tibialis anterior tendons: a retrospective study

The outcomes of 18 patients (11 females, 7 males; age, 40.4±11 years) at 2 years after ACL reconstruction with cryopreserved tibialis anterior allografts using a double bundle technique are presented. Most subjects (72%) described themselves as being moderately active before surgery. After providing written informed consent, subjects completed the 2000 IKDC Knee Form, underwent arthrometric knee measurements, and performed one-leg hop and isokinetic quadriceps and hamstring torque tests (60°/s). Ninety-four percent (17/18) of the subjects had normal or near-normal grades for manual knee ligament tests. Knee arthrometry measurements revealed a mean 1.1-mm involved side increase at 134 N (8.9±2 mm vs 7.8±3 mm) and a 2-mm involved side increase during manual maximum testing (11.3±2 mm vs 9.3±3 mm). Group means revealed active knee flexion (136±8° vs 139±6°) and knee hyper-extension (3±2° vs 5±2°), which were slightly reduced at the involved knee. One-leg hop testing revealed a 15% mean deficit at the involved side (0.81±0.3 m vs 0.95±0.3 m). Isokinetic testing revealed an 11% mean deficit at the involved side (143.4±60 Nm vs 161.8±54 Nm) for the quadriceps and 7% greater strength at the involved side (105.9±35 Nm vs 98.8±35 Nm) for the hamstrings. Side-to-side comparisons revealed that many patients displayed less than normal quadriceps femoris torque (72%, 13/18), hamstring torque (28%, 5/18) and hop test (28%, 5/18) performance. Moderate positive correlations existed between involved side quadriceps (r=0.80) and hamstring (r=0.83) torque/bodyweight and hop test performance. Scores were 77.6±21 (range 28.7–100) and 78.1±16 (range 41.7–100) for the 2000 IKDC Subjective Knee Evaluation and Health Assessment forms. Most subjects (83%, 15/18) rated their current function at 91% of pre-injury levels and all subjects continued to participate at their pre-injury perceived activity level. At 2 years after ACL reconstruction with tibialis anterior allografts, this subject group displayed satisfactory functional outcomes. Tibialis anterior allograft use provides an effective ACL reconstruction alternative, particularly for older individuals who want to continue recreational sports.     

Isokinetic quadriceps and hamstring muscle strength and knee function 5 years after anterior cruciate ligament reconstruction: comparison between bone-patellar tendon-bone and hamstring tendon autografts

Existing clinical studies have not proven which graft is to be preferred in anterior cruciate ligament (ACL) reconstruction. In recent years, bone-patellar tendon-bone and hamstring tendons have been the most frequently used graft types. Muscle strength deficit is one of the consequences after ACL reconstruction. The aim of this study was to evaluate possible differences in hamstring and quadriceps muscle strength and knee function 5 years after ACL reconstruction between the BPTB and the STG groups. The study group consisted of 288 patients (132 women, 156 men) with a unilateral ACL rupture who had received a BPTB (175 patients) or STG (113 patients) ACL reconstruction. Lower extremity concentric isokinetic peak extension and flexion torques were assessed at the angular velocities of 60°/s and 180°/s. The International Knee Documentation Committee (IKDC), the Tegner activity level, the Lysholm knee and the Kujala patellofemoral scores were also collected. Isokinetic quadriceps peak torque (percentage of the contralateral side) was 3.9% higher in the STG group than in the BPTB group at the velocity of 60°/s and 3.2% higher at the velocity of 180°/s and the isokinetic hamstring peak torque 2% higher in the BPTB group than in the STG group at the velocity of 60°/s and 2.5% higher at the velocity of 180°/s. In both groups the subjects had weaker quadriceps and hamstring muscle strength in the injured extremity compared with the uninjured one. In the single-leg hop test (according to the IKDC recommendations) there was a statistically significant difference (P = 0.040) between the groups. In the STG group, 68% of the patients had the single-leg hop ratio (injured vs. uninjured extremity) ≥90%, 31% of the patients 75–89% and 1% of the patients <75%, while in the BPTB group the corresponding percentages were 72, 21 and 7%. However, no statistically significant differences in clinical outcome were found between the groups as determined by the IKDC, Tegner activity level, Lysholm knee and Kujala patellofemoral scores.     

Comparison of clinical and dynamic knee function in patients with anterior cruciate ligament deficiency

BACKGROUND: Whether passive measures of isokinetic muscle strength deficits and knee laxity are related to the dynamic function of the anterior cruciate ligament-deficient knee remains unclear. HYPOTHESES: Arthrometer measurements are not predictive of peak external knee flexion moment (net quadriceps muscle moment), isokinetic quadriceps muscle strength correlates with peak external knee flexion moment (net quadriceps muscle moment), and isokinetic hamstring muscle strength correlates with peak external knee extension moment (net flexor muscle moment). STUDY DESIGN: Cross-sectional study. METHODS: Gait analysis was used to assess dynamic function during walking, jogging, and stair climbing in 44 subjects with unilateral anterior cruciate ligament deficiency and 44 control subjects. Passive knee laxity and isokinetic quadriceps and hamstring muscle strength were also measured. RESULTS: Arthrometer measurements did not correlate with peak external flexion or extension moments in any of the activities tested or with isokinetic quadriceps or hamstring muscle strength. Test subjects also had a significantly reduced peak external flexion moment during all three jogging activities and stair climbing compared with the control subjects and this was correlated with significantly reduced quadriceps muscle strength. CONCLUSIONS: Absolute knee laxity difference did not correlate with dynamic knee function as assessed by gait analysis and should not be used as a sole predictor for the outcome of treatment. Patients with greater than normal strength in the anterior cruciate ligament-deficient limb performed low- and high-stress activities in a more normal fashion than those with normal or less-than-normal strength.     

Joint laxity and isokinetic thigh muscle strength characteristics after anterior cruciate ligament reconstruction: bone patellar tendon bone versus quadrupled hamstring autografts.

OBJECTIVES: To analyze ligamentous stability and isokinetic strength of knee extensor and flexor muscles after anterior cruciate ligament reconstruction using 2 different autografts with identical fixation. DESIGN: This study implements a comparative case series design. SETTING: Schulthess Clinic, Switzerland. PATIENTS: A total of 153 consecutive patients (n = 87 bone-patellar tendon-bone [BPTB]/66 quadruple semitendinosus/gracilis tendons [QSGT] patients) who underwent BPTB and QSGT surgery were functionally assessed. INTERVENTION: All patients were functionally assessed (knee extension/flexion isokinetic strength and knee joint laxity) at a mean follow-up time of 11 months. MAIN OUTCOME MEASUREMENTS: Laxity was measured utilizing the Kneelax arthrometer, whereas isokinetic strength of the knee extensor/flexor muscle groups was measured using the Biodex Multi Joint System 2 (180 degrees/s and 300 degrees/s). RESULTS: The QSGT group had significantly greater knee joint laxity when compared with the BPTB group (P < 0.001). Furthermore, females in the QSGT group demonstrated the greatest knee joint laxity overall (P < 0.001). Additionally, a significant flexor torque deficiency was demonstrated in the QSGT group (P < 0.001); however, no differences in extensor torque were observed. CONCLUSIONS: The use of a BPTB autograft achieved better knee joint stability as well as greater knee flexor torque than the QSGT autograft. Both grafts exhibited a similar knee extensor torque deficit, indicating that only quadriceps strength is not graft-dependent.     

EMG power spectra of intercollegiate athletes and anterior cruciate ligament injury risk in females

PURPOSE: Females have a disproportionately high incidence of anterior cruciate ligament (ACL) injuries compared with males in analogous sports. Although the pathogenesis of this higher frequency has not been elucidated, gender differences in neuromuscular control of the knee may play an important role. This study evaluates EMG power spectra of the quadriceps and hamstring muscles during dynamic, fatiguing exercise to examine differences between male and female intercollegiate athletes. METHODS: Fifty-one collegiate basketball and soccer players (25 female, 26 male) were studied. Maximum voluntary contraction (MVC) was determined for knee flexion and extension. Three consecutive 2-min bouts of isokinetic knee flexion and extension exercise were performed at 40% MVC. EMG activity in the biceps femoris and vastus medialis obliquus was recorded using bipolar surface electrodes. RESULTS: MVC normalized to body weight was significantly greater in males than in females for the quadriceps (P< 0.01). Quadriceps coactivation ratios were significantly higher in females than in males during knee flexion exercises (P< 0.01). CONCLUSIONS: This study demonstrates differences in the EMG power spectra for females when compared with a matched group of males. Increased quadriceps coactivation in females may increase anterior tibial loads under dynamic conditions, thus placing the ACL at higher risk for injury in the female athlete.     

A prospective randomized study of patellar versus hamstring tendon autografts for anterior cruciate ligament reconstruction

BACKGROUND: Bone-patellar tendon-bone graft has been the most commonly used graft material in anterior cruciate reconstructions, but there has been increasing use of hamstring tendon grafts. However, no existing clinical studies show adequate support for the choice of one graft over the other. HYPOTHESIS: Hamstring tendons are equally as good as patellar tendon in anterior cruciate ligament reconstructions. STUDY DESIGN: Prospective randomized clinical trial. METHODS: Ninety-nine patients with laxity caused by a torn anterior cruciate ligament underwent arthroscopically assisted reconstruction with graft randomization according to their birth year. Grafts were either bone-patellar tendon-bone with metal interference screw fixation or double-looped hamstring tendons with metal plate fixation. There were no significant differences between the two groups preoperatively or at operation. Standard rehabilitation included immediate postoperative mobilization without a knee brace, protected weightbearing for 2 weeks, and return to full activity at 6 to 12 months. RESULTS: Forty-three patients in the patellar tendon group and 46 patients in the hamstring tendon group were available for clinical evaluation at a minimum of 21 months after surgery. No statistically significant differences were seen with respect to clinical and instrumented laxity testing, International Knee Documentation Committee Score ratings, isokinetic muscle torque measurements, and Kujala patellofemoral, Lysholm, and Tegner scores. CONCLUSION: Equal results were seen for patellar and hamstring tendon autograft anterior cruciate ligament reconstructions at 2 years after surgery. Both techniques seem to improve patients' performance.     

Short-term isokinetic and isometric strength outcomes after anterior cruciate ligament reconstruction in adolescents

ObjectivesTo examine differences in knee strength outcomes after ACL reconstruction according to quadriceps tendon (QT) or hamstring tendon (HT) autograft in adolescents.DesignRetrospective cohort.MethodsSurgical and clinical outcome data were collected. Analyses were conducted separately for female and male cohorts and grouped by graft type (HT or QT). A Mann-Whitney U test of independent samples was used to examine group differences according to graft type.Results107 females (age = 15.6 ± 1.5 years) and 94 males (age = 15.7 ± 1.5 years) were included. Mean time since surgery ranged from 7.2 to 7.9 months. Those with a QT autograft had decreased normalized isokinetic quadriceps peak torque on the involved limb compared to the HT group (p < 0.01, ES = 0.71–0.89). Normalized isometric hamstring peak torque was decreased for those with HT autograft in the female cohort (p = 0.02, ES = 0.57).ConclusionNormalized isokinetic quadriceps peak torque was reduced by 18–20% on the involved limb in those with a QT autograft. Normalized isometric hamstring peak torque was decreased by 13% for those with HT autograft in the female cohort. Method of strength testing may be an important consideration to fully appreciate strength deficits after ACL reconstruction according to graft type.