A computerized analysis of femoral condyle radii in ACL intact and contralateral ACL reconstructed knees using 3D CT

The bony geometry of the distal femoral condyles may have a significant influence on knee joint kinematics. The aim of this study was to analyze the relationship between the size of the medial and lateral femoral condyles in different planes. Seventy-four three-dimensional (3D) CT reconstructions of 37 patients with ACL intact and contralateral ACL reconstructed knees were used and the data were imported into a graphical software program. The radii of the medial and lateral femoral condyles were analyzed in the sagittal, coronal, and axial planes by digitally reconstructed circular arcs along the bony condylar profiles marked with multiple digital surface points. Intra- and interobserver testing was performed. In the intact knees the average sagittal radius of the distal medial and lateral femoral condyles was similar. There was a significant difference between the radii of the distal medial femoral condyles compared to lateral femoral condyles in the coronal plane (22.4 vs. 27.8 mm, P < 0.001) as well as between the radii of the medial femoral condyles in the axial plane in 90° knee flexion compared to the lateral femoral condyles (21.3 vs. 18.3 mm, P < 0.001). The average radius of the medial femoral condyles was significantly smaller in extension compared to 90° of flexion (21.2 vs. 22.4 mm, P = 0.05) and the average radius of the lateral femoral condyles was significantly larger in extension compared to 90° of flexion (27.8 vs. 18.3 mm, P < 0.001). The 37 ACL reconstructed knees demonstrated similar radii in all three planes when compared to the intact knees without any significant difference. The described method of assessing the architecture of the distal femoral condyles is non-invasive, reproducible, and provides reliable geometric parameters necessary for the 3D reconstruction of the femoral geometry in vivo. The radii of the FC were similar in the sagittal planes but demonstrate a significant asymmetry in the axial and coronal planes. The average radius of the lateral femoral condyles was significantly larger in extension whereas the radius of the medial femoral condyles was significantly larger in flexion. We did not find any significant difference in the shape of the femoral condyles in ACL intact and contralateral ACL reconstructed knees indicating that the geometry of the femoral condyles might not influence the injury mechanism of ACL rupture. The asymmetry between the femoral condyles may be considered when designing new anatomical femoral components in knee arthroplasty.     

Knee laxity modifications after ACL rupture and surgical intra- and extra-articular reconstructions: intra-operative measures in reconstructed and healthy knees

Purpose

Quantifying the effects of anterior cruciate ligament (ACL) deficiency on knee joint laxity is fundamental for understanding the outcomes of its reconstruction techniques. The general aim of this study was to determine intra-operatively the main modifications in knee laxity before and after standard isolated intra-articular and additional extra-articular anterolateral reinforcement. Our main hypothesis was that laxity abnormalities, particularly axial rotation, can still result from these ACL reconstruction techniques.

Methods

Thirty-two patients with primary ACL deficiency were analysed by a navigation system immediately before and after each of the two reconstructions. Laxity measurements in terms of knee translations and rotations were taken during the anteroposterior drawer test, with internal–external rotation at 20° and 90° of flexion, and varus–valgus and pivot-shift tests. All these laxity measures were also taken originally from the contralateral healthy knee.

Results

With respect to the contralateral healthy knee, in the ACL-deficient knee significantly increased laxity (expressed in %) was found in the medial compared with that of the lateral compartment, respectively, 115 and 68 % in the drawer test at 20° flexion, and 55 and 46 % at 90° flexion. In the medial compartment, a significant 35 % increment was also observed for the coupled tibial anteroposterior translation during axial knee rotation at 20° of flexion. After isolated intra-articular reconstruction, normal values of anteroposterior laxity were found restored in the pivot-shift and drawer tests in the lateral compartment, but not fully in the medial compartment. After the reinforcement, laxity in the medial compartment was also found restored in the axial rotation test at 20° flexion.

Conclusion

In ACL reconstruction, with respect to the contralateral knee, intra-articular plus additional anterolateral reinforcement procedures do not restore normal joint laxity. This combined procedure over-constrained the lateral compartment, while excessive laxity still persists at the medial one.

Level of evidence

III.

     

Ramp lesions in ACL deficient knees in children and adolescent population: a high prevalence confirmed in intercondylar and posteromedial exploration

Purpose

Ramp lesions are common in ACL deficient knees. Their diagnosis is difficult and, therefore, they may be underestimated. So far, no study analyzed their prevalence in a pediatric population. The diagnosis of these Ramp lesions is of major clinical relevance because of a frequent misestimating and technic difficulties. Ramp lesions might be associated with residual knee pain and instability after ACL reconstruction. The aim of this study was to evaluate the prevalence of ramp lesions explored through a systematic intercondylar and posteromedial arthroscopic approach during an ACL reconstruction in a pediatric and adolescent population.

Methods

Children and adolescents who underwent an ACL reconstruction were screened prospectively between October 2014 and 2016. The presence or absence of a ramp lesion was evaluated after each of three arthroscopic steps: (1) an anterior approach, (2) an intercondylar inspection, and (3) a posteromedial approach. Ramp lesions were screened at each step and their prevalence was evaluated. Furthermore, their presence was correlated to age, weight, size, sex, and state of the physis (open or closed). Finally, the meniscal status on MRI and arthroscopic findings were compared.

Results

Fifty-six patients were analyzed. The median age was 14.0?±?1.3 years (12–17). The median interval between injury and surgery was 11.5 months (1–108). During step 1 (anterior approach), only 1 ramp lesion (2%) was diagnosed. 13 (23%) ramp lesions were found after inspection through the intercondylar notch. No additional lesions were found with a direct view through the posteromedial approach. No correlation between ramp lesions and side, sex, weight, size, or state of physis was found. 10 ramp lesions out of 13 could not be diagnosed on MRI.

Conclusions

The prevalence of ACL-associated ramp lesions in children and adolescents is similar to adult populations. A systematic inspection through the intercondylar notch is recommended during ACL reconstruction to make a precise diagnosis. The posteromedial approach is essentially useful for meniscal repair

Level of evidence

Testing, previously developed diagnostic criteria in a consecutive series of patients and a universally applied “gold” standard, Level I.

     

The relationship between isokinetic quadriceps strength and laxity on gait analysis parameters in anterior cruciate ligament reconstructed knees

Gait alterations after ACL reconstruction have been reported in the literature. The current study examined a group of 14 patients who all had an ACL reconstruction with a patellar tendon autograft. Kinetic and kinematic data were obtained from the knee during walking. The flexion-extension deficit (FED) calculated from the angular difference between maximal flexion and maximal extension during the stance phase in the ACL-reconstructed and the normal knee was measured. We investigated whether these alterations in gait are related to quadriceps strength and residual laxity of the knee. It may be that patients modify their gait patterns to protect the knee from excessive anterior translation of the tibia by reducing the amount of extension during stance. On the other hand, persistent quadriceps weakness may also cause changes in gait patterns as the quadriceps is functioning as an important dynamic stabilizer of the knee during stance. Results showed that patients had a significantly higher FED value (4.9±4.0) than a healthy control group in a previous study (1.3±0.9). This is caused mainly by an extension deficit during midstance. External extension moments of the knee (T_ZMAX were significantly lower in the current patients group than in a healthy control group (T_ZMAX –0.27±0.19 Nm/kg in patients vs. –0.08±0.06 Nm/kg in controls). There were no significant correlations between quadriceps strength and gait analysis parameters. Furthermore no correlation was found between the amount of laxity of the knee and gait. The relevance of this study lies in the fact that apparently the measured gait alterations cannot be explained solely by often used biomechanical indicators such as laxity and strength. The measured gait alterations may be a result of the surgical procedure with subsequent modified motor programming.     

The effect of exercise on anterior-posterior translation of the normal knee and knees with deficient or reconstructed anterior cruciate ligaments

Exercise may result in increased laxity in the knee. Anterior translation in 40 normal knees, 33 consecutive anterior cruciate ligament-deficient knees, and 30 randomly chosen anterior cruciate ligament-reconstructed knees was measured using the KT-1000 arthrometer before and after the participants ran for 15 minutes on a neutral-incline treadmill. A single observer blinded to the status of each knee tested all participants. There was a significant increase in anterior translation in the normal (mean, 0.75 mm), anterior cruciate ligament-deficient (mean, 0.62 mm), and anterior cruciate ligament-reconstructed knees (mean, 0.25 mm) after exercise. In addition, the amount of anterior translation after exercise was significantly different when these groups were compared with each other. Post hoc analysis using Tukey's procedure indicated that anterior translation in the anterior cruciate ligament-reconstructed knee was significantly less than in the normal and anterior cruciate ligament-deficient knees. Therefore, repetitive loading exercise contributes to an increase in anterior translation in normal, anterior cruciate ligament-deficient, and anterior cruciate ligament-reconstructed knees, and the anterior cruciate ligament-reconstructed knee does not respond to repetitive loading in the same manner as a normal knee.     

Size comparison of ACL footprint and reconstructed auto graft

Purpose

The purpose of this study was to compare the size of native anterior cruciate ligament (ACL) footprints and the size of commonly used auto grafts. The hypothesis was that the reconstructed graft size with auto grafts might be smaller than the native ACL footprint.

Methods

Fourteen non-paired human cadaver knees were used. The semitendinosus tendon (ST) and the gracilis (G) tendon were harvested and prepared for ACL grafts. Simulating an ST graft, the ST was cut in half. The bigger half was regarded as the antero-medial (AM) bundle, and the remaining half was regarded as the postero-lateral (PL) bundle. Simulating an ST–G graft, the bigger half of the ST and G were regarded as the AM bundle, and the smaller half of the ST was regarded as the PL bundle. Each graft diameter was measured, and the graft area was calculated. Simulating a rectangular bone-patella tendon-bone (BPTB) graft, a 10-mm wide BPTB graft was harvested and the area calculated. The ACL was carefully dissected, and the size of the femoral and tibial footprints was measured using Image J software (National Institution of Health).

Results

The average areas of the ST, ST–G, and BPTB graft were 52.3 ± 7.3, 64.4 ± 9.2, and 32.7 ± 6.5 mm², respectively. The sizes of the native femoral and tibial ACL footprints were 85.4 ± 26.3 and 145.4 ± 39.8 mm², respectively. Only the ST–G graft showed no significant difference in graft size when compared with the femoral ACL footprint.

Conclusion

Only the ST–G auto graft was able to reproduce the native size of the ACL footprint on the femoral side. None of the auto grafts could reproduce the size of the tibial ACL footprint. For clinical relevance, ST–G graft is recommended in order to reproduce the native size of the ACL in anatomical ACL reconstruction with auto graft.     

Gore-Tex prosthetic ligament in anterior cruciate deficient knees

Reconstruction for symptomatic anterior cruciate deficient knees has yielded varying success rates. Prosthetic cruciate replacement has recently become a potentially attractive alternative. The results of the Gore-Tex polytetrafluoroethylene ligament, which is intended as a permanent replacement, are reported. Eighty-two patients were followed prospectively, mean age was 28 years (range, 16 to 51 years) and mean followup was 18 months (range, 12 to 30 months). Subjective scores improved in all categories, including pain, swelling, giving way, locking, and stair climbing. All patients without complications had no episodes of actual giving way, considered themselves improved, and returned to activities of daily living at 3 weeks and athletics at 8 months. Range of motion lacking at 3 months was 2 degrees of extension and 10 degrees of flexion, and at 12 months was 0 degrees of extension and 4 degrees of flexion. All mean objective data, including the anterior drawer, Lachman, and pivot shift, demonstrated improvement at final followup. Cybex testing revealed improvement in relative quadriceps strength from 88% to 99%. The KT-1000 Arthrometer showed improvement in the injured-normal knee difference score throughout the follow-up period. Of importance is that while final objective data was improved over initial data, an early nonprogressive shift toward loosening was indicated by worsening of the drawer, Lachman, pivot shift, and KT-1000 scores. This shift may be attributed to resorption of interposed soft tissue, creep, or loosening of the graft. Subjective scores remained stable after improving. Complications included four ruptures, four chronic sterile effusions with partial attenuation, one infection, and one symptomatic loose body.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reconstruction of anterior cruciate ligament deficient knees in soccer players with an iliotibial band autograft. A prospective study of 132 reconstructed knees followed for 4 (2-7) years

One hundred and thirty-two consecutive soccer players (117 males and 15 females, median age 23, range 16-39 years) underwent primary reconstruction of the anterior cruciate ligament (ACL) with an iliotibial band (ITB) autograft. All patients were followed prospectively for a minimum of 2 years. One hundred and eighteen patients (89%) attended an independent observer follow-up after a median of 47 (24-92) months. The time before participating in soccer was a median of 7 (5-24) months. At a median of 4 years, 80 (68%) were still active soccer players, while 38 had changed activity to a lower level. Twenty-five gave up soccer playing for reasons unrelated to the knee, and 13 (11%) gave up due to problems from the reconstructed knee. The Lysholm score improved from a median of 82 (range 42-99, mean [SD] 80.5 [+/-11.9]) points prior to the operation to a median of 99 (range 57-100, mean [SD] 94.6 [+/-8.5]) at follow-up. The Tegner score improved from a median of 3.5 (0-7) preoperatively to 9 (1-10). Four patients (3%) sustained a rupture of the graft: three ruptures occurred among the 15 females (20%), and one was seen among the 117 males (0.8%) (P=0.01). Eight per cent had predominantly minor cosmetic complaints from the donor-site hernia, while 51% had temporary discomfort from the staples used for graft fixation. Using the ITB autograft for ACL reconstruction, we found excellent and good results in soccer players with ACL deficiency and high demands for optimal knee function. The failure rate in general was comparable with other methods, and the majority was still active in soccer sports at a median of 4 years after surgery. An unacceptably high rerupture rate was registered in female players.     

Anatomic double-bundle ACL reconstruction restricts knee extension in knees with hyperextension

Purpose

Double-bundle ACL reconstruction has been demonstrated to be at least as effective as single-bundle reconstruction in terms of restoring knee rotational and translational stability. Until now, the influence on knees with hyperextension has not been evaluated. It was the purpose of this study to evaluate whether double-bundle ACL reconstruction restricts extension in hyperextendable knees.

Methods

Hamstring tendon reconstructions of 10 human cadaveric knees with the ability of hyperextension (age: 48 ± 14 years) were performed as single bundle (SB) on one side and double bundle (DB) on the other side. A surgical navigation system (BrainLab, Germany) was used to assess the kinematics of each knee at the intact and reconstructed state. A difference with regard to the anterior-to-posterior translation (AP) and rotational stability at 30° of knee flexion, 90° of flexion and the hyperextension capability of each specimen was analysed.

Results

The difference in AP translation before and after the reconstruction was not significantly different in 30° and 90° of flexion (n.s). Both single- and double-bundle reconstructions restored the preoperative kinematics at 30° and 90° of knee flexion (n.s). The knee extension was 4° ± 1.8° with the intact ACL and 4° ± 1.7° after reconstruction in the SB group (n.s). The knee extension was 5° of hyperextension ± 1.1° with the intact ACL and 0° ± 0.4° after reconstruction in the DB group; the limitation of the extension was significantly larger in this group (p = 0.013).

Conclusion

Both single- and double-bundle ACL reconstruction techniques are capable of restoring knee anteroposterior and rotational stability. Double-bundle reconstructions significantly reduce knee extension in knees with hyperextension capability. Care must be taken when using double-bundle techniques in patients with knee hyperextension as this procedure may limit the knee extension after double-bundle ACL reconstruction.     

Combined ACL reconstruction and closing-wedge HTO for varus angulated ACL-deficient knees

Purpose

To report the medium-term clinical and radiographic outcomes of a group of patients who underwent anterior cruciate ligament (ACL) surgery combined with high tibial osteotomy (HTO) for varus-related early medial osteoarthritis (OA) and ACL deficiency knee.

Methods

Thirty-two patients underwent single-bundle over-the-top ACL reconstruction or revision surgery and a concomitant closing-wedge lateral HTO. The mean age at surgery was 40.1 ± 8.1 years. Evaluation at a mean of 6.5 ± 2.7 years of follow-up consisted of subjective and objective IKDC, Tegner Activity Level, EQ-5D, VAS for pain and AP laxity assessment with KT-1000 arthrometer. Limb alignment and OA changes were evaluated on radiographs.

Results

All scores significantly improved from pre-operative status to final follow-up. KT-1000 evaluation showed a mean side-to-side difference of 2.2 ± 1.0 mm. Two patients were considered as failures. The mean correction of the limb alignment was 5.6° ± 2.8°. Posterior tibial slope decreased at a mean of 1.2° ± 0.9°. At final follow-up, the mechanical axes crossed the medial–lateral length of tibial plateau at a mean of 56 ± 23 %, with only 1 patient (3 %) presenting severe varus alignment. OA progression was recorded only on the medial compartment (p = 0.0230), with severe medial OA in 22 % of the patients. No patients underwent osteotomy revision, ACL revision, UKA or TKA.

Conclusions

The described technique allowed patients with medial OA, varus alignment and chronic ACL deficiency to restore knee laxity, correct alignment and resume a recreational level of activity at 6.5 years of follow-up.

Level of evidence

Case series with no comparison group, Level IV.     

The effects of proprioceptive or strength training on the neuromuscular function of the ACL reconstructed knee: a randomized clinical trial

OBJECTIVES: The purpose of this study was to determine the effects of a proprioceptive training program (PT) vs. a strength training (ST) program on neuromuscular function after anterior cruciate ligament (ACL) reconstruction. The second purpose was to establish the determinants of functional ability for the operated limb. METHODS: Ten participants with unilateral ACL reconstructions were randomly assigned to one of the following 12-week training protocols: (1) isotonic ST, and (2) PT. The outcome measures were: (1) peak torque time of the hamstring muscles (PeakTT), (2) average concentric and eccentric torques of the quadriceps and hamstring muscles, (3) one-legged single hop for distance (SLHD), (4) one-legged time hop (TH), and (5) subjective scores. RESULTS: : There was a significant group by time interaction effect for PeakTT (P = 0.017). The PT group demonstrated greater percent change in isokinetic torques than the ST group at the end of the 12 weeks (P < or = 0.05). Participants in both groups demonstrated similar significant gains in functional ability and subjective scores (P < or = 0.014). Quadriceps strength is a determinant of functional ability for the operated limb (R2 = 0.72). CONCLUSIONS: : Both training protocols influenced PeakTT. The beneficial effects of ST on PeakTT appear to be load-dependent, while sufficient practice may be crucial in maintaining PeakTT improvements induced by PT. Proprioceptive training alone can induce isokinetic strength gains. Restoring and increasing quadriceps strength is essential to maximize functional ability of the operated knee joint.     

Functional outcome following reconstruction in chronic multiple ligament deficient knees

Multiligament knee injuries are rare but potentially limb-threatening conditions. In this study we aim to evaluate the mid- and long-term functional outcome of patients who underwent arthroscopically assisted multiple ligament reconstruction for chronic multiple knee ligament deficiency. Thirty-five patients (27 males and 8 females) with an average age of 35.1 years (range: 17–60) were included in this study. Follow-up ranged from 12 to 124 months (average: 40.3). On final follow-up patients had a mean loss of extension of 3.1°, while flexion ranged from 95° to 135° (average: 118.4°). The functional outcome according to Clancy’s criteria was excellent in 7 patients (20%), good in 14 (40%), fair in 11 (31.4%), while 3 reconstructions resulted in failure (8.6%). Patients scored an average of 4.03 (range: 1–9) in their Tegner Activity Scale, while their score in Activities of Daily Living Scale of the Knee Outcome Survey ranged from 25 to 98 with an average of 72.7. Sixteen patients returned to sporting activities and all but three returned to work. Early operative treatment of multiple ligament injuries is preferable, as it may allow for anatomic repair instead of reconstruction of ligamentous structures. This study demonstrates though, that even if acute reconstruction has not or could not be performed, reconstruction in chronic multiple ligament deficient knees should be attempted. Although this complex and technically demanding procedure rarely results in a “normal” knee, it offers in most cases very satisfactory stability and a significant improvement in knee function.     

Magnetic resonance imaging of meniscal degeneration in torn menisci: a comparison between anterior cruciate ligament deficient knees and stable knees

Signal anomalies observed in magnetic resonance imaging of the intrameniscal tissue adjacent to the tear were compared between stable knees (group 1, 54 menisci) and anterior cruciate ligament (ACL) deficient knees (group 2, 98 menisci). The histological significance of these signal anomalies was also studied (n = 25). The frequency of intrameniscal signal anomalies adjacent to the tear was significantly lower in ACL-deficient knees than in ACL-stable knees (P = 0.0022). There was a close correlation between the imaging anomalies and the presence of histological lesions (fissures, degeneration) within meniscal tissues adjacent to the tear (sensitivity: 0.95, specificity: 0.60). Our results suggest that the severity of intrameniscal degenerative changes adjacent to the tear are lower in ACL-deficient knees than in ACL-stable knees.     

Tennis specific limitations in players with an ACL deficient knee

Background

Complete rupture of the anterior cruciate ligament (ACL) causes significant alteration of knee joint kinematics. Untreated patients often develop joint instability, chronic articular degeneration, and knee dysfunction. Demands on the ACL produced by playing tennis have not been investigated.

Objective

To identify subjective sport‐specific limitations in tennis players with isolated unilateral ACL deficiency.

Study design

Prospective case–control study.

Methods

16 players (mean (SD) age, 39.9 (2.3) years; 14 men) with a chronic unilateral ACL deficient knee and 16 healthy controls (38.25 (8.47) years; 14 men) were recruited. ACL deficiency was confirmed by clinical and magnetic resonance imaging. A Lysholm score was obtained in all patients, together with subjective evaluation of their current tennis performance compared with pre‐injury levels, applying a 0–100% visual scale. Both groups completed a questionnaire on tennis specific abilities.

Results

Lysholm scores were: 85.6 (10.3) points in the study group and 100 (0) points in the control group (p<0.001, t test for independent samples). Injured players evaluated their current tennis performance as 66.8 (15.2)% compared with 100% pre‐injury level (p<0.005, t test for dependent samples). Abilities affected in the ACL deficient group were landing after a smash stroke (p<0.001); stopping abruptly and changing (p<0.001); playing a three set singles match (p<0.05); and playing on a hard court surface (p<0.001, Kolmogorov‐Smirnov test).

Conclusions

There are specific limitations associated with complete isolated ACL rupture, including subjective tennis performance impairment, limitations landing after a smash, stopping and changing step direction, difficulties playing a three set singles match, and playing on hard court surfaces.     

The knee adduction moment in hamstring and patellar tendon anterior cruciate ligament reconstructed knees

Purpose

The external knee adduction moment during gait has previously been associated with knee osteoarthritis, and although it has been shown to be greater following anterior cruciate ligament (ACL) reconstruction surgery compared to a control group, it has not been compared between different graft types. Given that the incidence of radiographic knee osteoarthritis appears to be greater following patellar tendon compared to hamstring tendon ACL reconstruction, this study tested the hypothesis that the knee adduction moment would also be increased following patellar tendon ACL reconstruction.

Methods

In 48 male participants (16 patellar tendon graft, 16 hamstring graft and 16 controls), the external knee adduction moment was measured during level walking in a gait laboratory at mean of 10?months after surgery.

Results

There was no difference in the knee adduction moment between the hamstring and patellar tendon groups, and both patient groups had a significantly reduced knee adduction moment compared to the control group. In the hamstring group, the smaller adduction moment was associated with the patients walking with less knee varus whereas in the patellar tendon group, the smaller moment was associated with the patients walking with a decreased vertical ground reaction force.

Conclusions

These results indicate that in male patients during the early stages of recovery from ACL reconstruction, the knee adduction moment is not greater than controls for either hamstring or patellar tendon graft types. Although the knee adduction moment was similar between the two graft types, the overall magnitude of the moment was influenced by different biomechanical factors.

Level of evidence

III.     

Dynamics of muscle strength improvement during isokinetic rehabilitation of athletes with ACL rupture and chondromalacia patellae

AIM: To assess quantitatively dynamics and extent of the increase in muscle strength during isokinetic rehabilitation. METHODS: Experimental design: daily measurements of muscle strength; detailed testing at the beginning and at the end of rehabilitation. Setting: Cybex Rehabilitation Center, Zagreb. Subjects: 44 athletes (31 m, 13 F, age 16-35), 3 injury-defined groups: athletes with ACL rupture (non-reconstructed and reconstructed) and chondromalacia patellae. Interventions: all subjects underwent isokinetic rehabilitation on Cybex Orthotron KT2 device, using individually designed protocols (extension and flexion exercises, concentric muscle contractions, 15 treatments). Measurements: monitoring of daily progress on rehabilitation device and detailed testing on diagnostic device. RESULTS: All patients showed considerable improvement. Muscle strength improved on average 141% (SD=110) in ACL-reconstructed group, 144% (SD=130) for chondromalacia patellae group and 150% (SD=74) for ACL-non-reconstructed group, comparing to initial strength. Dynamic status tested on Cybex Otrhotron diagnostic device prior and after rehabilitation strongly correlated with final progress monitored on the rehabilitation device. CONCLUSION: Isokinetic rehabilitation is a quick and effective method in treating knee injuries in athletes. Both types of objective criteria have shown significant increase in muscle strength. The improvement of muscle strength was on the average 149% (SD=101), which is about 10% daily for 15 treatments. The greatest progress, 19% per day, occurred during first five days. The athletes were able to resume their sport activities as follows: patients from chondromalacia patellae group, and most of them from the non-reconstructed ACL group were back in competition within a month, while 75% from the ACL reconstructed group came back within 3 months, and the rest of them within 5 months.     

Comparative injury rates of uninjured, anterior cruciate ligament-deficient, and reconstructed knees in a skiing population.

To evaluate the risks of skiing after anterior cruciate ligament injury with or without reconstruction, we performed a 3-year study of 5646 skiers employed by a large ski resort. All skiers underwent knee ligament examinations before entering the study. The participants were divided into three groups based on whether they had never had an anterior cruciate ligament injury (N = 4748), were unilaterally deficient of the ligament (N = 138), or had undergone a unilateral reconstruction of the ligament at least 1 year before (N = 274). The rates of knee injuries requiring evaluation by a physician or time off work were calculated. The results of the reconstructed knees were further evaluated to determine whether ligament repair with semitendinosus/gracilis or patellar tendon autograft had a higher injury rate. Compared with knees with intact anterior cruciate ligaments, ligament-deficient knees had a 6.2-times higher rate of injuries, and knees in which the ligament had been reconstructed had a 3.1-times higher rate. The differences between each of the three groups were significant. Injuries to ligament-intact knees were less severe, with 13% requiring surgery, while 39% of the injuries in the ligament-deficient and 41% of the injuries in the reconstructed-ligament knees required surgery. The rates of injury for the graft types were not significantly different, but skiers with a semitendinosus/gracilis tendon autograft were significantly more likely to rupture their graft than skiers with a patellar tendon autograft.     

High intensity running results in an impaired neuromuscular response in ACL reconstructed individuals

Anterior cruciate ligament (ACL) reconstruction reestablishes electromyographic activity during moderate activities such as walking but is unclear if this is also the case in sports activities such as high intensity running that results in accumulation of metabolic fatigue. Nine bone-patella tendon-bone ACL reconstructed athletes were evaluated 19.2 (5.7) months post-operatively using a telemetric electromyographic system. The neuromuscular response of vastus lateralis and biceps femoris muscles was tested bilaterally on separate occasions during 10 min running at moderate intensity (20% below the lactate threshold) and 10 min running at high intensity (40% above the lactate threshold). During moderate intensity running, electromyographic activity did not change for either leg. During high intensity running, electromyographic activity did not change for the vastus lateralis of the ACL reconstructed leg [267.8 (142.8)–263.8 (128.9) μV, P > 0.05] while it increased significantly [294.2 (120.6)–317.1 (140.5) μV, P = 0.03] for the vastus lateralis of the intact leg. High intensity exercise that is associated with accumulation of metabolic fatigue, results in an impaired neuromuscular response for the vastus lateralis muscle of the ACL reconstructed leg.     

The Gore-Tex prosthetic ligament as a salvage procedure in deficient knees

The purpose of this study was to evaluate the results of prosthetic ligament replacement of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) with the Gore-Tex polytetrafluorethyene prosthesis (W.L.Gore and Co., Flagstaff, Ariz.) in 52 patients (54 knees). All patients sustained multiple (failed) knee operations or had knees with gross instability. Twenty-eight (29 knees) of the ¶52 patients (54%) in whom the Goretex prosthesis was still in situ were available at a minimum follow-up of 5 years (mean 9 years, range 5–11 years). The mean age at examination was 39 years (range 30–57 years); there were 15 men and 13 women. The results of the procedure were compared with the results of the same patients at a mean follow-up of 3 years. Eighty-one percent of the patients of the whole group complained about pain. This was 78% for the patients with an ACL reconstruction and 75% for the patients with a PCL reconstruction. The Tegner activity score and the Lysholm knee score showed a statistically significant difference over time. The anterior instability pattern improved in only 43% of the knees and the posterior instability in 41% of the knees. The Lachman test showed also a significant difference over time. In all patients X-ray showed an increase in degenerative changes. In conclusion, the PTFE prosthetic ligament in the reconstruction of the ACL and the PCL in the (chronically) unstable knee seems to deteriorate over time.