The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior–posterior laxity patterns

The issue of the best place to attach an anterior cruciate ligament graft to the femur is controversial, and different anatomic or isometric points have been recommended. It was hypothesised that one attachment site could be identified that would be best for restoring normal anterior–posterior laxity throughout the range of knee flexion. It was also hypothesised that these different attachment sites would cause different graft tension patterns during knee flexion. Using six cadaver knees, an isometric point was found 3 mm distal to the posterior edge of Blumensaats line, at the 10:30–11:00 oclock position in right knees, at the antero-proximal edge of the anatomic ACL attachment. Anterior–posterior laxity was measured at ±150 N draw force at 20–120° flexion with the knee intact and after anterior cruciate ligament transection. The graft was placed at the isometric point, and AP laxity was restored to normal at 20° flexion, then measured at other angles. Graft tension was measured throughout, and also during passive flexion–extension. This was repeated for four other graft positions around the isometric point in every knee. Laxity was restored best by grafts tensioned to a mean of 9±14 N, positioned isometrically and 3 mm posterior to the isometric point. Their tension remained low until terminal extension. Grafts 3 mm anterior to the isometric point caused significant overconstraint, and had higher tension beyond 80° knee flexion. Small changes in attachment site had large effects on laxity and tension patterns. These results support an isometric/posterior anatomic femoral graft attachment, which restored knee laxity to normal from 20 to 120° flexion and did not induce high graft tension as the knee flexed. Grafts attached to the roof of the intercondylar notch caused overconstraint and higher tension in the flexed knee.     

Does the sequence of onset of rigor mortis depend on the proportion of muscle fibre types and on intra-muscular glycogen content?

We examined the postmortem changes in the levels of ATP, glycogen and lactic acid in two masticatory muscles and three leg muscles of rats. The proportion of fibre types of the muscles was determined with NIH image software. The ATP levels in the white muscles did not decrease up to 1 h after death, and the ATP levels 1 and 2 h after death in the white muscles were higher than those in the red muscles with a single exception. The glycogen level at death and 1 h after death and the lactic acid level 1 h after death in masticatory muscles were lower than in the leg muscles. It is possible that the differences in the proportion of muscle fibre types and in glycogen level in muscles influences the postmortem change in ATP and lactic acid, which would accelerate or retard rigor mortis of the muscles. Received: 18 August 1998 / Received in revised form: 26 October 1998 / Accepted: 23 November 1998     

Is repetition failure critical for the development of muscle hypertrophy and strength?

This investigation sought to determine the effect of resistance training to failure on functional, structural and neural elbow flexor muscle adaptation. Twenty‐eight males completed a 4‐week familiarization period and were then counterbalanced on the basis of responsiveness across; non‐failure rapid shortening (RS; rapid concentric, 2 s eccentric), non‐failure stretch‐shortening (SSC; rapid concentric, rapid eccentric), and failure control (C, 2 s concentric, 2 s eccentric), for a 12‐week unilateral elbow flexor resistance training regimen, 3 × week using 85% of one repetition maximum (1RM). 1RM, maximal voluntary contraction (MVC), muscle cross‐sectional area (CSA), and muscle activation (EMG_RMS) of the agonist, antagonist, and stabilizer muscles were assessed before and after the 12‐week training period. The average number of repetitions per set was significantly lower in RS 4.2 [confidence interval (CI): 4.2, 4.3] and SSC 4.2 (CI: 4.2, 4.3) compared with C 6.1 (CI: 5.8, 6.4). A significant increase in 1RM (30.5%), MVC (13.3%), CSA (11.4%), and agonist EMG_RMS (22.1%) was observed; however, no between‐group differences were detected. In contrast, antagonist EMG_RMS increased significantly in SSC (40.5%) and C (23.3%), but decreased in RS (13.5%). Similar adaptations across the three resistance training regimen suggest repetition failure is not critical to elicit significant neural and structural changes to skeletal muscle.     

Is there a correlation between isometric muscle strength and the kinematics of the pelvis,hip and knee during functional tasks in women with patellofemoral pain?

ObjectivesTo evaluate the correlation between isometric muscle strength of the hip abductors (HABD) and lateral rotators (HLR) with the range of motion (ROM) of the pelvis/hip in the frontal/transverse planes, respectively, and between the strength of the knee extensors (KExt) with the ROM of the knee in the sagittal plane during seven tasks.DesignCross-sectional study.SettingLaboratory.ParticipantsThirty-five women with patellofemoral pain.Main outcome measuresMaximum isometric muscle strength of the HABD, HLR, and KExt was measured using a manual dynamometer, and pelvis and lower limbs kinematics were evaluated using 3D optical system during gait, ascending and descending stairs, the forward and lateral step down tests, and the propulsion and landing phases of the single leg hop test (SLHT).ResultsA weak correlation was found between KExt strength and knee ROM in the sagittal plane (p = 0.05; r = −0.33) during SLHT landing, and a moderate correlation between HABD strength and ROM of pelvic obliquity (p < 0.01; r = 0.50) during ascending stairs.ConclusionsThe lower strength of KExt has a weak correlation with higher knee flexion during the landing phase of the SLHT, and the lower strength of HABD has a moderate correlation with lower pelvis ROM in the frontal plane when ascending stairs.     

Influence of stress relaxation and load during static stretching on the range of motion and muscle–tendon passive stiffness

Sport Sciences for Health - Passive torque during static stretching was decreased. This phenomenon occurs due to stress relaxation. However, no studies have investigated the relationship stress...     

A parametric study of effect of experimental tibialis posterior muscle pain on joint loading and muscle forces—Implications for patients with rheumatoid arthritis?

BackgroundFoot pain and deformities are commonly encountered in patients with rheumatoid arthritis (RA). Likewise, Posterior tibial tendon dysfunction (PTTD) is commonly involved in development of foot and ankle abnormalities and has been reported with a prevalence in two-thirds of the RA patients.Research questionRedundancy in the physiological function between different muscles provides the central nervous system multiple options to perform the same movement but which muscles compensate for the impairment of the tibialis posterior (TP) muscle? And how does these changes affect ankle joint loading?MethodsExperimental and computational disciplines were applied to investigate changes in muscle forces as result of induced pain in the right TP muscle. Twelve healthy subjects were enrolled in the study. Experimental pain was induced in the TP by a single ultrasound graphically guided injection of 1 mL hypertonic saline (5.0% Sodium Chloride). The participants' gait was assessed by skin marker-based motion capture and force plates. Musculoskeletal models were used to investigate compensation mechanisms systematically in the lower under extremity when TP muscle was recruited less as a consequence of the induced pain.ResultsExperimental TP muscle pain and simulated reduced strength caused altered muscle recruitment and made the flexor digitorum longus and flexor hallucis longus muscles compensated for the impairment of the TP muscle. Further, the resultant ankle joint force was increased as the strength of the TP muscle was reduced.SignificanceThe compensation mechanism observed in the present study indicate that alterations in muscle recruitment and muscle force distribution as a result of the underlying disease inflammation itself may contribute to development of chronic foot pain and deformities in patients with RA. Further studies are required to understand the role of PTTD in occurrence of those late adverse musculoskeletal manifestations aiming at search for early preventive strategies.     

Where should the femoral tunnel of a posterior cruciate ligament reconstruction be placed to best restore anteroposterior laxity and ligament forces?

BACKGROUND: Objective results of posterior cruciate ligament reconstruction are often less than satisfactory, with many patients exhibiting excessive posterior laxity. HYPOTHESIS: Changes in the position of the femoral tunnel within the posterior cruciate ligament's femoral footprint will significantly affect anteroposterior laxities and graft forces. STUDY DESIGN: Controlled laboratory study. METHODS: The posterior cruciate ligament's femoral origin was mechanically isolated in 13 fresh-frozen knee specimens, and the bone cap containing the ligament's insertion was attached to a load cell that recorded resultant force during tibial loading tests. Anteroposterior laxity (at +/- 200 N applied force) was also measured. Cast acrylic replicas of the bone cap were fabricated, with tunnels placed in anterolateral, central, and posteromedial regions of the footprint. A graft reconstruction was tested in each tunnel. RESULTS: Mean laxities with the anterolateral tunnel were +0.9 mm to +1.7 mm greater than normal between 0 degrees and 45 degrees of flexion. Mean laxities with the posteromedial tunnel were -2.4 mm to -3.7 mm less than normal between 10 degrees and 45 degrees of flexion. Mean laxities with the central tunnel were not significantly different from intact knee values, except at 0 degrees (0.9 mm greater). Mean graft forces with the anterolateral tunnel were normal for most modes of loading, whereas there were significant increases in graft forces with the posteromedial and central tunnels. CONCLUSION: The anterolateral tunnel reproduced normal posterior cruciate ligament force profiles but produced a knee that was more lax than normal between 0 degrees and 45 degrees of flexion. The central tunnel best matched intact knee laxities, but graft forces were higher than posterior cruciate ligament forces between 0 degrees and 45 degrees of flexion. The posteromedial tunnel overconstrained anteroposterior laxity approximately 2 to 4 mm between 0 degrees and 45 degrees of flexion and generated higher graft forces in the same flexion range. CLINICAL RELEVANCE: This study suggests that a posteromedial tunnel should not be used for single-bundle posterior cruciate ligament reconstruction.     

Bipositional MR imaging vs arthrography for the evaluation of femoral head sphericity and containment in Legg-Calvé-Perthes disease

Eleven hips of 10 patients with Legg-Calvé-Perthes disease (LCPD) were examined by arthrography and magnetic resonance (MR) imaging. Arthrogram and MR images were obtained with the hips in neutral position and in 20 degrees flexion-abduction and internal rotation. Modified arthrographic index (AI) was used for the evaluation of sphericity and acetabulum head index (AHI) was used for the assessment of containment. According to AI, there is no significant difference between the arthrograms and coronal MR imaging, but the difference between the coronal and sagittal MR imaging was significant. There was no statistical difference between the arthrograms and MR measurements in terms of AHI. Anterior flattening of the femoral head and the effect of hip flexion in the containment at the sagittal plane could be demonstrated clearly in sagittal MR imaging. Even if there was significant flattening in coronal plane, the sphericity of the head was preserved in the sagittal plane. Bipositional MR imaging is comparable to arthrography for the demonstration of sphericity and containment of the femoral head in both coronal and sagittal planes in LCPD.     

Application of the new insertion–deletion polymorphism kit for forensic identification and parentage testing on the Czech population

Insertion-deletion polymorphisms (INDELs) are diallelic markers derived from a single mutation event. Their low mutation frequency makes them suitable for forensic and parentage testing. The examination of INDELs thus combines advantages of both short tandem repeats (STR) and single nucleotide polymorphisms (SNP). This type of polymorphisms may be examined using as small amplicon size as SNP (about 100 bp) but could be analyzed by techniques used for routine STR analysis. For our population study, we genotyped 55 unrelated Czech individuals. We also genotyped 11 trios to analyze DIPplex Kit (QIAGEN, Germany) suitability for parentage testing. DIPplex Kit contains 30 diallelic autosomal markers. INDELs in DIPplex Kit were tested with linkage disequilibrium test, which showed that they could be treated as independent markers. All 30 loci fulfill Hardy–Weinberg equilibrium. There were several significant differences between Czech and African populations, but no significant ones within European population. Probability of a match in the Czech population was 1 in 6.8?×?10¹²; combined power of discrimination was 99.9999999999%. Average paternity index was 1.13–1.77 for each locus; combined paternity index reached about 27,000 for a set of 30 loci. We can conclude that DIPplex kit is useful as an additional panel of markers in paternity cases when mutations in STR polymorphisms are present. For application on degraded or inhibited samples, further optimization of buffer and primer concentrations is needed.     

Sagittal flexion angle of the femoral component in unicompartmental knee arthroplasty: is it same for both medial and lateral UKAs?

The flexion of the femoral component in the sagittal plane in unicompartmental knee arthroplasty (UKA) was analyzed radiographically in this study. Thirty medial and 30 lateral UKAs were included. The sagittal flexion angles were measured both relative to the posterior femoral cortex and midline sagittal distal femoral axis. Both of the measurement methods revealed that the femoral components were inserted in a significantly more flexed fashion in the medial UKA group. Neither preoperative nor postoperative tibial slope did have any significant effect on the sagittal flexion angle. To the best of our knowledge, this is the first study demonstrating an angular difference in the sagittal flexion of the femoral components between medial and lateral UKAs.     

Influence of light conditions (colour temperature and illuminance) on the evaluation of root translucency for the application of Lamendin’s age-at-death estimation technique

International Journal of Legal Medicine - Estimation of age-at-death represents a central focus in forensic human identification, as it is a key parameter used in the identification of unidentified...     

Concomitant injuries may not reduce the likelihood of achieving symmetrical muscle function one year after anterior cruciate ligament reconstruction: a prospective observational study based on 263 patients

Purpose

A better understanding of patient characteristics and the way common concomitant injuries affect the recovery of muscle function after surgery should help providers to treat patients with anterior cruciate ligament (ACL) injuries. The aim of this study was to determine whether patient characteristics, concomitant injuries and graft choice at ACL reconstruction were associated with symmetrical knee muscle function at one year. The hypothesis was that the presence of concomitant injuries would negatively influence the opportunity to achieve symmetrical knee function at the one-year follow-up.

Methods

Data was extracted from the Swedish National Knee Ligament Register and a rehabilitation outcome register between August 2012 and December 2016. The patients had been evaluated with a battery of tests comprising knee extension and flexion strength, vertical jump, hop for distance and the side-hop test one year after ACL reconstruction. Univariable and multivariable logistic regression analyses were performed with achieving a limb symmetry index (LSI) of ≥?90% in all tests of muscle function as primary outcome.

Results

A total of 263 patients with a mean age of 26.7?±?10.3 years were included in the study (47% females). No patient demographic or intra-operative predictors were found to be significant when attempting to predict the achievement of a symmetrical muscle function. Lateral meniscus injury and a patellar tendon autograft reduced the odds of achieving an LSI of ≥?90% in knee extension strength, OR?=?0.49 [(95% CI 0.25–0.97), p?=?0.039] and OR?=?0.30 [(95% CI 0.14–0.67), p?=?0.0033] respectively. In addition, reduced odds of recovering knee extension strength were found in older patients, OR?=?0.76 [(95% CI 0.60–0.98), p?=?0.034]. A higher pre-injury level of physical activity increased the odds of recovering knee flexion strength, OR?=?1.14 [(95% CI 1.01–1.29), p?=?0.037].

Conclusion

Intra-operatively identified concomitant injuries or graft choice did not affect the likelihood of recovering symmetrical performance in five different tests of muscle function one year after ACL reconstruction. However, fewer than one in four patients achieved an LSI of ≥?90% in all tests.

Level of evidence

Prospective observational study: Level 2.