Persisting side-to-side differences in bone mineral content, but not in muscle strength and tendon stiffness after anterior cruciate ligament reconstruction

Quadriceps Performance and Running Biomechanics Influence Femur BMD Changes after ACL Reconstruction in Collegiate Athletes

PURPOSE

Reduced bone mineral density of the distal femur (BMD DF ) can persist long term after anterior cruciate ligament reconstruction (ACLR), even in athletes who return to high levels of competition. These deficits may have implications for the onset and progression of knee osteoarthritis. It is unknown if clinically modifiable factors are associated with losses in BMD DF . This study evaluated the potential influence of knee extensor peak torque (PT), rate of torque development (RTD), as well as peak knee flexion (PKF) angle and peak knee extensor moment (PKEM) during running, on longitudinal changes in BMD DF post-ACLR.

METHODS

After ACLR, 57 Division I collegiate athletes underwent serial whole-body dual-energy x-ray absorptiometry (DXA) scans between 3 and 24 months post-ACLR. Of these, 43 athletes also had isometric knee extensor testing (21 female, 105 observations), and 54 had running analyses (26 female, 141 observations). Linear mixed-effects models, controlling for sex, assessed the influence of surgical limb quadriceps performance (PT and RTD), running mechanics (PKF and PKEM), and time post-ACLR on BMD DF (5% and 15% of femur length). Simple slope analyses were used to explore interactions.

RESULTS

Athletes with RTD less than 7.20 (N·m)·kg -1 ·s -1 (mean) at 9.3 months post-ACLR demonstrated significant decreases in 15% BMD DF over time ( P = 0.03). Athletes with PKEM during running less than 0.92 (N·m)·kg -1 (-1 SD below mean) at 9.8 months post-ACLR demonstrated significant decreases in 15% BMD DF over time ( P = 0.02). Significant slopes were not detected at -1 SD below the mean for PT (1.75 (N·m)·kg -1 , P = 0.07) and PKF (31.3°, P = 0.08).

CONCLUSIONS

Worse quadriceps RTD and running PKEM were associated with a greater loss of BMD DF between 3 and 24 months post-ACLR.

State of the mineralized tissue comprising the femoral ACL enthesis in young women with an ACL failure

Despite poor graft integration among some patients that undergo an anterior cruciate ligament (ACL) reconstruction, there has been little consideration of the bone quality into which the ACL femoral tunnel is drilled and the graft is placed. Bone mineral density of the knee decreases following ACL injury. However, trabecular and cortical architecture differences between injured and non-injured femoral ACL entheses have not been reported. We hypothesize that injured femoral ACL entheses will show significantly less cortical and trabecular mass compared with non-injured controls. Femoral ACL enthesis explants from 54 female patients (13-25 years) were collected during ACL reconstructive surgery. Control explants (n = 12) were collected from seven donors (18-36 years). Injured (I) femoral explants differed from those of non-injured (NI) controls with significantly less (p ≤ 0.001) cortical volumetric bone mineral density (vBMD) (NI: 736.1-867.6 mg/cm3 ; I: 451.2-891.9 mg/cm3 ), relative bone volume (BV/TV) (NI: 0.674-0.867; I: 0.401-0.792) and porosity (Ct.Po) (NI: 0.133-0.326; I: 0.209-0.600). Injured explants showed significantly less trabecular vBMD (p = 0.013) but not trabecular BV/TV (p = 0.314), thickness (p = 0.412), or separation (p = 0.828). We found significantly less cortical bone within injured femoral entheses compared to NI controls. Lower cortical and trabecular bone mass within patient femoral ACL entheses may help explain poor ACL graft osseointegration outcomes in the young and may be a contributor to the osteolytic phenomenon that often occurs within the graft tunnel following ACL reconstruction.

Bone mineral decreases in the calcanei in men after arthroscopic shoulder surgery: a prospective study over 5 years

PURPOSE

It is well known that injuries and surgical procedures in the lower extremities affect bone mineral both in the injured limb and in the contralateral limb. The possible effect on bone mineral after upper extremity surgery is not well studied, and the aim of this study was to study the effect on bone mineral in the calcanei after arthroscopic shoulder surgery.

METHODS

Twenty-two men scheduled for arthroscopic shoulder surgery underwent bone mineral area (BMA) mass measurements in both calcanei using the Calscan DXL device prior to surgery and after 6, 18, 36 and 60 months. On every occasion, the Tegner activity score and EuroQoL 5-dimensions (EQ-5D) were assessed.

RESULTS

During 5 years, there was a significant decrease in the BMA in both calcanei (p = 0.003). The Tegner activity score decreased from preinjury to the operation and did not increase significantly after the operation. The EQ-5D increased significantly after the operation.

CONCLUSION

The bone mineral in the calcanei in men during the 5-year study period decreased more than the expected age-dependent decline after arthroscopic shoulder surgery. There was an increase in health-related quality of life as measured with the EQ-5D after arthroscopic Bankart reconstruction.

LEVEL OF EVIDENCE

Case-control study, Level III.

Measurement of regional trabecular bone attenuation of the knee following anterior cruciate ligament rupture

INTRODUCTION

The purpose of this study was to determine regional trabecular bone attenuation changes of the knee using computed tomography after anterior cruciate ligament rupture.

MATERIALS AND METHODS

Thirty one patients'-computed tomography images of the injured knees were used to measure trabecular bone attenuation in seven predetermined regions.

RESULTS

Trabecular bone attenuation at four of seven regions (anteromedial area of the proximal tibia, anterolateral area of the proximal tibia, posteromedial area of the proximal tibia, and posterocentral area of the proximal tibia) was negatively correlated with the duration after injury. Independent negative correlation between the duration after injury and the density in anteromedial area of the proximal tibia was detected.

CONCLUSIONS

After anterior cruciate ligament injury, trabecular bone attenuation of the knee decreases by time in certain regions of proximal tibia. Anteromedial region is the most significantly effected of all, which it is the anterior cruciate ligament fixation area.

From mechanical stimulus to bone formation: A review

Bone is a remarkable tissue that can respond to external stimuli. The importance of mechanical forces on the mass and structural development of bone has long been accepted. This adaptation behaviour is very complex and involves multidisciplinary concepts, and significant progress has recently been made in understanding this process. In this review, we describe the state of the art studies in this area and highlight current insights while simultaneously clarifying some basic yet essential topics related to the origin of mechanical stimulus in bone, the biomechanisms associated with mechanotransduction, the nature of physiological bone stimuli and the test systems most commonly used to study the mechanical stimulation of bone.

Long-Term Examination of Bone Mineral Density in the Calcanei After Anterior Cruciate Ligament Reconstruction in Adolescents and Matched Adult Controls

PURPOSE

The aims were to evaluate the results 10 to 20 years after anterior cruciate ligament (ACL) reconstruction performed in adolescents in terms of bone mineral density (BMD) in the calcanei using the dual-energy x-ray absorptiometry (DXA) technique, activity level, and quality of life.

METHODS

A case-control study of adolescents who underwent ACL reconstruction between 1992 and 2002 was performed. The inclusion criterion was a unilateral ACL injury. The exclusion criteria were bilateral ACL injury, contralateral ACL reconstruction, posterior cruciate ligament injury, and previous or present fractures of either lower extremity. The BMD was measured in both calcanei using the DXA technique and compared with a control group of adult ACL-reconstructed patients and with a DXA reference database. The age of the control group was similar to that of the patient group at the time of BMD assessment, performed 60 months after reconstruction. Activity was measured with the Tegner activity scale. The EQ-5D was used to evaluate quality of life.

RESULTS

Thirty-two adolescents (11 boys and 21 girls), aged 12 to 16 years, with a symptomatic unilateral ACL rupture, underwent reconstruction at near skeletally mature age. Of these patients, 29 (91%) took part in the follow-up examination. The BMD values for the male patients were lower on the injured and non-injured sides (-15.2% [P = .02] and -11.8% [P = .05], respectively) compared with the control group. The values for the female patients were -0.8% (P = .84) and -2.2% (P = .69), respectively. Correspondingly, the BMD values for the male patients were lower on the injured and non-injured sides (-8.2% and -4.9%, respectively) compared with the male reference database. The BMD values for the female patients were higher on the injured and non-injured sides (4.1% and 4.3%, respectively) compared with the female reference database. In the control group, female patients had a significantly lower value for the Tegner activity scale preoperatively (median, 2.0; range, 0 to 5) than the female patients in the study group (median, 3.0; range, 2 to 8) (P = .006). In the study group, the Tegner activity scale at follow-up showed a significant correlation with the BMD on the injured side for male patients (ρ = 0.67, P = .03) but not on the non-injured side (ρ = 0.50, P = .14). In the control group, the Tegner activity scale at follow-up showed a significant correlation with the BMD on the non-injured side for female patients (ρ = 0.61, P = .03) but not on the injured side (ρ = 0.34, P = .25). The Tegner activity scale and EQ-5D showed no significant differences between the study groups.

CONCLUSIONS

In the long-term, the BMD in the calcanei of patients who were adolescents at the time of ACL reconstruction differed from that of a control group and a reference database. This study indicates that boys with an ACL injury and subsequent ACL reconstruction run a subsequent risk of a significantly lower BMD in their calcanei as adults and, consequently, an increased future fracture risk.

LEVEL OF EVIDENCE

Level III, case-control study.

Bone mineral density changes in the knee following anterior cruciate ligament rupture

OBJECTIVE

The pathophysiology of anterior cruciate ligament (ACL) rupture leading to knee osteoarthritis (OA) remains largely unknown. It seems that bone loss occurs after ACL rupture. The purpose of our study was to determine bone mineral density (BMD) changes in the knee after ACL rupture during 2-year follow-up period and to compare BMD changes between the injured and healthy contralateral knee.

DESIGN

Patients were included in an observational prospective follow-up study within 6 months after ACL trauma and evaluated for 2 years. Patients were treated operatively or non-operatively. At baseline and at the one- and 2-year follow-ups, BMD was measured in six regions of the tibia and femur for both knees (medial, central, lateral) using a Dual-energy X-ray Absorptiometry (DXA) scanner.

RESULTS

One hundred forty-one patients were included, with the following characteristics: 66% were male, median age at baseline was 25.3 (inter-quartile range 11.3) years, and 63% were treated operatively. After 1 year, BMD was significantly lower in all regions of the injured knee of the operatively treated patients compared to baseline. After 2 years, BMD was significantly increased, but remained lower than the baseline levels. In all regions for all measurements, the mean BMD was significantly lower in the injured knee than in the healthy contralateral knee.

CONCLUSIONS

During a 2-year follow-up period after ACL rupture, the BMD level in the injured knee was found to be lower than in the healthy contralateral knee. In operatively treated patients, the BMD decreased in the first year and increased in the second follow-up year.

Anterior cruciate ligament reconstruction reduces bone mineral areal mass

PURPOSE

The aim of this study was to prospectively follow bone mineral areal mass (BMA) changes in the calcaneii, hips, and lumbar spine after anterior cruciate ligament (ACL) reconstruction using hamstring tendon autografts.

METHODS

Patients with a unilateral ACL injury scheduled for reconstruction were included in the study. The BMA mass was measured in both calcaneii, the hips, and the lumbar spine using the dual-energy x-ray absorptiometry (DEXA) technique. Quality of life was estimated using the EQ-5D questionnaire, and activity was measured using the Tegner activity score. The patients were assessed before surgery and after 6, 18, 36, and 60 months.

RESULTS

Forty-eight patients (21 female and 27 male patients), median age 31 years (17 to 64 years), participated in the study for 5 years. After 5 years, the female patients had lost 9.5% (P < .001) and 10.1% (P < .001) of their BMA in the calcaneus on the operated and nonoperated sides, respectively. Correspondingly, the male patients had lost 6.5% (P = .004) and 8.5% (P < .001) on the operated and nonoperated sides, respectively. In the hips, the female patients had lost 4.0% (P < .001) and 2.7% (P < .001) on the operated and the nonoperated sides, respectively. Among the male patients, the BMA loss was 3.4% (P = .002) and 4.8% (P < .001) in the hips on the operated and the nonoperated sides, respectively. The EQ-5D index was a mean (standard deviation [SD]) of 0.72 (0.23) before surgery and 0.86 (0.17) (P < .001) after 5 years. The preinjury Tegner activity level was a median (range) 7.5 (1 to 10). The preoperative Tegner activity level was 2.5 (0 to 9) and increased to 4 (1 to 9) (P = .002) after 5 years.

CONCLUSIONS

Both female and male patients had a significant decrease in BMA in both calcaneii and both hips during the 5-year study period compared with a reference population of Swedish healthy women and men. The patients increased their Tegner activity level and improved their EQ-5D index during the 5-year follow-up period.

LEVEL OF EVIDENCE

Level II, prognostic prospective study.

Effectiveness of low-profile supplemental fixation in anterior cruciate ligament reconstructions with decreased bone mineral density

PURPOSE

The purpose of this study was to compare anterior cruciate ligament (ACL) fixation using a bioabsorbable interference screw (BIS) and a supplemental low-profile suture anchor (PushLock 4.5-mm polyetheretherketone anchor; Arthrex, Naples, FL) with a standard BIS fixation to determine if fixation methods were dependent on tibial bone mineral density (BMD).

METHODS

Ten matched pairs of fresh-frozen human female knee specimens (20 total) were harvested with specimen ages ranging from 40 to 65 years. The BMD for each specimen was determined with a dual-energy x-ray absorptiometry scanner. The specimens were divided into 2 groups, 1 with a BIS and the other with a BIS plus a PushLock. Tibial-sided ACL fixation with hamstring tendon grafts was performed on all the specimens. Then, load to failure and stiffness were biomechanically tested.

RESULTS

The BIS-plus-PushLock specimens had a significantly higher mean yield load compared with specimens with the BIS alone (702 N v 517 N, P = .047). However, in samples with lower bone density, there was no statistically significant difference in failure loads between fixation techniques (P = .8566 at BMD of 0.5 g/cm(2)). As the bone density of the samples increased, the failure loads increased for both techniques (P < .0001 for PushLock and P = .0057 for BIS). This BMD-associated increase was greater for the PushLock (P = .0148), resulting in a statistically significant difference in failure load at the upper range tested (P = .0293 at BMD of 0.9 g/cm(2)).

CONCLUSIONS

Supplemental fixation of ACL reconstructions with a PushLock is beneficial in persons with a normal BMD of the proximal tibia, but at a lower BMD, there was no difference in our study.

CLINICAL RELEVANCE

Individuals with normal BMDs may benefit from this supplemental fixation. However, caution should be used in postmenopausal women or individuals with chronic ACL injuries when using this fixation strategy.

Bike racing, recreational riding, impact sport and bone health

Cycling has been shown to confer considerable benefits in terms of health, leading to reductions in death rates principally due to cardiovascular improvements and adaptation. Given the disparity between the benefits of cycling on cardiovascular fitness and previous research finding that cycling may not be beneficial for bone health, Hugo Olmedillas and colleagues performed a systematic review of the literature. They concluded that road cycling does not appear to confer any significant osteogenic benefit. They postulate that the cause of this is that, particularly at a competitive level, riders spend long periods of time in a weight-supported position on the bike. Training programs may be supplemented with impact loading to preserve bone health; however, the small increased risk of soft tissue injury must also be considered. See related commentary http://www.biomedcentral.com/1741-7015/10/168

Arthroscopic management of chronic patellar tendinopathy

BACKGROUND

In patients with patellar tendinopathy in whom nonoperative management is unsuccessful, surgery is an option to return to high levels of physical activity. Although open surgery is traditionally advocated, an arthroscopic approach may be safe and effective.

PURPOSE

This study was undertaken to analyze medium- and long-term outcome of 64 patients undergoing arthroscopic surgery for the management of patellar tendinopathy after failing nonoperative treatment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 64 patients (73 knees), 27 of whom were professional athletes, with patellar tendinopathy refractory to nonoperative management underwent arthroscopic debridement of the adipose tissue of the Hoffa's body posterior to the patellar tendon, debridement of abnormal patellar tendon, and excision of the lower pole of the patella. Preoperative and postoperative evaluation was undertaken using the International Knee Documentation Committee (IKDC), Lysholm knee scale, and Victorian Institute of Sport Assessment-Patella (VISA-P) scores for all patients at 1 and 3 years. No patients were lost to follow-up. Forty-three and 29 patients were similarly assessed at 5 and 10 years, respectively, after surgery. Return to sports and rehabilitation was also assessed.

RESULTS

The IKDC, Lysholm, and VISA-P scores all significantly improved at 1 and 3 years' follow-up. The average preoperative IKDC score of 51.6 improved to 86.4 at both the 1- and 3-year stage. The average preoperative Lysholm score of 52.3 improved to 94.7 at 1-year follow-up and was 95.5 at 3-year follow-up. The average preoperative VISA-P score of 35.3 improved to 69.8 at the 1-year stage and was 70.7 at the 3-year follow-up. These scores remained significantly better for the patients assessed at 5 and 10 years' follow-up. There were no postoperative complications. Nineteen of the 27 professional athletes returned to sports at the same level. Seven patients developed pain after sports within 3 years after the operation, a failure rate of 7 of 73 knees (9.6%). All patients were able to return to sports by 3 months.

CONCLUSION

Arthroscopic surgery for patients with patellar tendinopathy, refractory to nonoperative management, appears to provide significant improvements in symptoms and function, with improvements maintained for at least 3 years. These results suggest that some patients may not be able to achieve their presymptom sporting level; or if they do, they may participate in sports with some degree of residual symptoms. Limited data show that these improvements are maintained for up to 10 years. Early return to sports may also be achieved.