Cruciate ligament laxity and femoral intercondylar notch narrowing in early-stage knee osteoarthritis

OBJECTIVE: The influence of the cruciate ligaments in spontaneous osteoarthritis (OA) is not understood, although ligament rupture is known to cause secondary OA. Additionally, femoral notch narrowing at the anterior cruciate ligament (ACL) insertion site is associated with disease severity, but it is unknown whether ligament deterioration precedes or follows osteophyte formation. We examined cruciate ligament mechanics and metabolism and the intercondylar notch width in OA-prone Dunkin-Hartley (DH) guinea pigs at ages up to and including the age at OA onset (24 weeks), and compared the data with those in age-matched controls (Bristol strain 2 [BS2] guinea pigs). METHODS: Guinea pigs were assessed at 3, 6, 9, 12, 16, 20, 24, and 36 weeks of age. ACLs were mechanically tested, and the intercondylar notch width index (NWI) was determined. Cruciate ligament metabolism was determined by measuring the following markers of collagen turnover: matrix metalloproteinase 2 (MMP-2), tissue inhibitor of metalloproteinases 2, C-terminal type I procollagen propeptide (PICP), and the immature collagen-derived crosslink dihydroxylysinonorleucine (DHLNL). RESULTS: DH guinea pigs had significantly laxer ACLs than did BS2 guinea pigs, at 12, 16, and 24 weeks. We observed elevated levels of pro and active MMP-2, PICP, and DHLNL in the cruciate ligaments of DH animals at most ages, compared with BS2 guinea pigs. The NWI in DH animals was significantly lower than that in BS2 guinea pigs at 24 and 36 weeks. CONCLUSION: In DH guinea pigs, laxer ACLs, which are associated with increased collagen turnover, may cause joint instability and predispose these animals to the early onset of OA. Decreased intercondylar notch width in the DH animals indicates that bone remodeling at the ACL insertion site is a response to elevated ACL laxity.     

Cruciate ligament laxity and femoral intercondylar notch narrowing in early‐stage knee osteoarthritis

Objective

The influence of the cruciate ligaments in spontaneous osteoarthritis (OA) is not understood, although ligament rupture is known to cause secondary OA. Additionally, femoral notch narrowing at the anterior cruciate ligament (ACL) insertion site is associated with disease severity, but it is unknown whether ligament deterioration precedes or follows osteophyte formation. We examined cruciate ligament mechanics and metabolism and the intercondylar notch width in OA‐prone Dunkin‐Hartley (DH) guinea pigs at ages up to and including the age at OA onset (24 weeks), and compared the data with those in age‐matched controls (Bristol strain 2 [BS2] guinea pigs).

Methods

Guinea pigs were assessed at 3, 6, 9, 12, 16, 20, 24, and 36 weeks of age. ACLs were mechanically tested, and the intercondylar notch width index (NWI) was determined. Cruciate ligament metabolism was determined by measuring the following markers of collagen turnover: matrix metalloproteinase 2 (MMP‐2), tissue inhibitor of metalloproteinases 2, C‐terminal type I procollagen propeptide (PICP), and the immature collagen‐derived crosslink dihydroxylysinonorleucine (DHLNL).

Results

DH guinea pigs had significantly laxer ACLs than did BS2 guinea pigs, at 12, 16, and 24 weeks. We observed elevated levels of pro and active MMP‐2, PICP, and DHLNL in the cruciate ligaments of DH animals at most ages, compared with BS2 guinea pigs. The NWI in DH animals was significantly lower than that in BS2 guinea pigs at 24 and 36 weeks.

Conclusion

In DH guinea pigs, laxer ACLs, which are associated with increased collagen turnover, may cause joint instability and predispose these animals to the early onset of OA. Decreased intercondylar notch width in the DH animals indicates that bone remodeling at the ACL insertion site is a response to elevated ACL laxity.

     

Immobilization of the knee prevents osteoarthritis after anterior cruciate ligament transection

The effect of immobilization of the knee in flexion on the development of osteoarthritis was studied in dogs that had undergone transection of the anterior cruciate ligament. Knees of dogs that were permitted ad libitum ambulation in a pen for 12 weeks after transection of the ligament showed osteophytes and fibrillation and a decrease in proteoglycan (uronic acid) content, although thickness of the articular cartilage was normal. Proteoglycan synthesis was 80% greater (P < 0.01) than that in cartilage from the contralateral knee, and more than twice the normal proportion of the total proteoglycans was present in the medium of cultures of cartilage from the unstable knee (P < 0.01). Similarly, the proportion of total tissue proteoglycans extracted with 0.4M guanidinium chloride was 3 times greater than normal (P < 0.01). In contrast, osteophytes were not seen when the leg was immobilized in flexion immediately after transection of the ligament, and the articular surface remained intact. The cartilage became atrophic, however, and its proteoglycan content (uronic acid) was diminished; proteoglycan synthesis was decreased to 61% of the level in cartilage from the contralateral knee, although proteoglycan extractability was normal. Knee cartilage from these legs that were immobilized after transection, therefore, resembled that from dogs whose leg had been immobilized without cruciate ligament transection. In cartilage from all operated and/or immobilized joints the proportion of proteoglycans that interacted with hyaluronic acid in vitro was diminished, because of a defect in the hyaluronate-binding region of the proteoglycan.     

Posttraumatic anterior cruciate ligament insufficiency as a cause of osteoarthritis in a knee joint

Summary The purpose of the present investigation was to examine and describe the osteoarthritic changes that chronic, partial or complete anterior cruciate ligament (ACL) insufficiency causes to the knee joint. The most characteristic findings in 77 patients with average follow-up of eight years were osteophytes and subchondral sclerosis of femoral and tibial medial condyles, tibial eminence and patella, as well as narrowing of medial or lateral joint space. Only five patients (14%) in the group with partial, but 28 (70%) of those with complete insufficiency of the ACL suffered from a clear posttraumatic osteoarthritis of the injured knee. In complete tears, the total extent of these pathological changes per patient was fourfold compared to the patients with partial tear. It was concluded that chronic, posttraumatic insufficiency of the ACL causes characteristic osteoarthritic changes to the injured knee and that the amount of these changes seems to depend on the amount of the insufficiency. Therefore, a quick restoration of the static and dynamic stability of the injured knee must be the privilege of every knee injury patient in order to prevent the development of premature osteoarthritis     

Paracetamol in osteoarthritis of the knee

BACKGROUND: Paracetamol is a recommended symptomatic treatment of osteoarthritis (OA), but in clinical trials sample sizes have been relatively small and variable daily doses of paracetamol have been used. OBJECTIVES: To determine the therapeutic efficacy of paracetamol in OA of the knee and identify predictive factors of clinical response to treatment. METHODS: A double blind, parallel group, placebo controlled trial of analgesic efficacy and safety of paracetamol versus placebo including 779 patients with OA of the knee. Patients were randomly assigned to receive paracetamol 4 g/day (n = 405) or placebo (n = 374) for 6 weeks. Symptomatic OA of the knee was required at inclusion with global pain intensity of the knee during physical activities for the past 24 hours of >or=30 mm on a 100 mm visual analogue scale. The primary end point was a 30% decrease of global pain intensity of the knee. Intention to treat analyses were performed. RESULTS: The percentage of responders did not differ significantly between groups: 52.6% and 51.9% in paracetamol and placebo groups, respectively (p = 0.840). In a subgroup of patients with chronic mechanical knee pain without signs of inflammation (n = 123), the mean change in pain intensity from baseline was 25.2 mm v 15.2 mm, in the paracetamol (n = 63) and placebo (n = 60) groups, respectively-mean difference 10.0 mm; 95% CI 1.0 to 19.0; p = 0.0294. No serious adverse events were attributable to treatment. CONCLUSION: A statistically significant symptomatic effect of oral paracetamol 4 g/day over placebo was not found, suggesting that paracetamol use in symptomatic OA of the knee should be further explored. The tolerability and safety of paracetamol, at the recommended maximum dose of 4 g/day, was confirmed over 6 weeks.     

Total knee arthroplasty for osteoarthritis of the knee

The indication, preoperative condition, surgical technique and postoperative rehabilitation of total knee arthroplasty for osteoarthritis are summarized. I think the point of contributing to the success of total knee arthroplasty are to discuss the preoperative condition, to know well the instrument, to do the accurate osteotomy and to obtain the correct soft tissue balancing.     

Structural factors associated with malalignment in knee osteoarthritis: the Boston osteoarthritis knee study

OBJECTIVE: Osteoarthritis (OA) is a multifactorial condition. The progression of knee OA is determined in part by mechanical effects on local structures. One of the mechanical influences on cartilage loss is limb alignment. We explored the structural factors associated with malalignment in subjects with symptomatic OA. METHODS: We conducted a cross-sectional assessment using The Boston Osteoarthritis of the Knee Study, a natural history study of symptomatic knee OA. Baseline assessments included knee magnetic resonance imaging (MRI) and information on weight and height. Long-limb radiographs to assess mechanical alignment were obtained at 15 months. Subarticular bone attrition, meniscal degeneration, anterior and posterior cruciate ligament integrity, medial and lateral collateral ligament integrity, marginal osteophytes, and cartilage morphology were assessed on MRI using a semiquantitative, multi-feature scoring method (Whole-Organ MRI Score) for whole-organ evaluation of the knee that is applicable to conventional MRI techniques. We also quantified the following meniscal position measures on coronal MRI images in both medial and lateral compartments: subluxation, meniscal height, and meniscal covering of the tibial plateau. Using the long-limb radiographs, mechanical alignment was measured in degrees on a continuous scale. The purpose of this cross-sectional analysis was to determine the individual and relative contribution of various structural factors to alignment of the lower extremity. We assessed the cross-sectional association between various structural factors and alignment of the lower extremity using a linear regression model. RESULTS: The 162 subjects with all measures acquired had a mean age of 67.0 years (SD 9.2), body mass index 31.4 (SD 5.6); 30% were female and 77% of knees had a Kellgren-Lawrence grade > or = 2. The main univariate determinants of varus alignment in decreasing order of influence were medial bone attrition, medial meniscal degeneration, medial meniscal subluxation, and medial tibiofemoral cartilage loss. Multivariable analysis revealed that medial bone attrition and medial tibiofemoral cartilage loss explained more of the variance in varus malalignment than other variables. The main univariate determinants of valgus malalignment in decreasing order of influence were lateral tibiofemoral cartilage loss, lateral osteophyte score, and lateral meniscal degeneration. CONCLUSION: Cartilage loss has been thought to be the major determinant of alignment. We found that other factors including meniscal degeneration and position, bone attrition, osteophytes, and ligament damage contribute to the variance of malalignment. Further longitudinal analysis is required to determine cause and effect relationships. This should assist researchers in determining strategies to ameliorate the potent effects of this mechanical disturbance.     

Neurogenic inflammation in osteoarthritis of the knee

Abstract

The synovium in a knee joint has an extensive neural network in the somatic and autonomic nervous systems. In medial compartmental osteoarthritis of the knee, neuropeptides were most abundant, with an especially large number of substance P and calcitonin gene-related peptide-immunoreactive free nerve endings. Some of the substance P-positive nerve endings were surrounded by monocytes. Substance P and calcitonin gene-related peptide were found more frequently in the medial than in the lateral or suprapatellar areas. Substance P-positive free nerve endings showed more dendritic morphologic features in the medial region than those in the lateral and suprapatellar regions, and small nerves were accompanied by newly developed vessels in synovial villi. In the medial region, the synovitis was more remarkable than in the lateral region. Patients suffering from medial compartmental osteoarthritis of the knee complain of pain on the anteromedial portion of the knee joint when walking or standing. Therefore, these findings suggest that free nerve endings containing substance P may be implicated in the development and persistence of inflammatory synovitis and the pain pathway in osteoarthritis of the knee.     

Neurogenic inflammation in osteoarthritis of the knee

The synovium in a knee joint has an extensive neural network in the somatic and autonomic nervous systems. In medial compartmental osteoarthritis of the knee, neuropeptides were most abundant, with an especially large number of substance P and calcitonin gene-related peptide-immunoreactive free nerve endings. Some of the substance P-positive nerve endings were surrounded by monocytes. Substance P and calcitonin gene-related peptide were found more frequently in the medial than in the lateral or suprapatellar areas. Substance P-positive free nerve endings showed more dendritic morphologic features in the medial region than those in the lateral and suprapatellar regions, and small nerves were accompanied by newly developed vessels in synovial villi. In the medial region, the synovitis was more remarkable than in the lateral region. Patients suffering from medial compartmental osteoarthritis of the knee complain of pain on the anteromedial portion of the knee joint when walking or standing. Therefore, these findings suggest that free nerve endings containing substance P may be implicated in the development and persistence of inflammatory synovitis and the pain pathway in osteoarthritis of the knee.     

Back pain in osteoarthritis of the knee

Objective. To compare patients with knee osteoarthritis (OA) who have and do not have back pain, and evaluate the prevalence, characteristics, and consequences of back pain among knee OA patients. Methods. During a 3-year period, consecutive patients attending an outpatient rheumatology clinic were evaluated for the presence of back pain, and 368 were found to have OA of the knee. Clinical status was evaluated by the Clinical Health Assessment Questionnaire, radiographs, and joint examinations. Results. Back pain was present in 54.6% of patients with OA of the knee. Almost every clinical status measure was worse among those reporting back pain, including Health Assessment Questionnaire (HAQ) disability, pain, global severity, fatigue, and psychological status. Back pain was more common in women and the obese, but was not associated with age, marital status, formal education, smoking history, or knee radiographic scores. In multivariate analyses the strongest correlates of back pain in knee OA patients were anxiety, night pain, HAQ disability, and global severity. Conclusion. Back pain is prevalent among OA clinic patients, more common than in rheumatoid arthritis or population studies, is linked to body mass index, and is associated with clinically significant increases in pain and other measures of clinical distress.     

Surgery for osteoarthritis of the knee

The role of surgical treatment in osteoarthritis of the knee continues to evolve. The indications for arthroscopy have narrowed. Orthopedic surgeons continue to explore options less invasive than total knee replacement for isolated unicompartmental arthritis of the knee joint. In addition to arthroscopy, this article discusses the merits and drawbacks of and indications for osteotomy, interpositional arthroscopy, patellofemoral replacements, and emerging technologies for total knee replacements.     

Efficacy of EMG-biofeedback in knee osteoarthritis

This study was designed to investigate the additive effect of EMG-biofeedback in rehabilitation of knee osteoarthritis. Forty patients, aged 45–70, with the diagnosis of knee osteoarthritis according to American College of Rheumatology (ACR) criteria were taken into the study. The patients were randomly assigned in two groups. One group (n = 20) received strengthening exercise program with EMG-biofeedback while the other group (n = 20) had the same exercise program without biofeedback for 3 weeks. The clinical outcome was assessed on the basis of pain with visual analog scale (VAS), function with Western Ontario McMaster Osteoarthritis Index (WOMAC) and quality of life with Nottingham Health Profile (NHP). Quadriceps strength was measured with Cybex isokinetic dynamometer, isokinetically at the angular velocities of 60 and 180°/s and isometric strength at 65° of knee flexion. Pain, WOMAC scores and muscle strength improved in both groups but there was no statistically significant differences between two groups (p > 0.05). In both groups physical mobility, pain scores of NHP improved significantly (p < 0.001) while in EMG-biofeedback group energy and sleep scores also improved after treatment (p < 0.05). As reported in the literature, in our study, strengthening exercises improved pain, function, muscle strength and quality of life in patients with knee osteoarthritis. But it seems that there is no significant additive effect of EMG-biofeedback to regular strengthening exercise program in these patients.     

Update in surgery for osteoarthritis of the knee

Osteoarthritis is a leading cause of disability with incidence and prevalence rising in most nations. Management to address the degenerative joint is stratified according to degree of severity of involvement and always begins with non-surgical modalities before progressing through a range of surgeries, including arthroscopy, osteotomy, unicompartmental and total knee replacement. Predictability of results depends on the type of procedure with total joint replacement giving the most sustainable relief from symptoms, improvement of function and longevity of construct. Obesity is a health priority in developed countries where it is overrepresented in patients presenting for joint replacement. Complications, poor patient satisfaction and joint function can be directly attributable to obesity. Efforts to address obesity should be considered as part of the approach to managing osteoarthritis.     

Exercise for knee osteoarthritis

Adverse outcomes in knee osteoarthritis include pain, loss of function, and disability. These outcomes can have devastating effects on the quality of life of those suffering from the disease. Treatments have generally targeted pain, assuming that disability would improve as a direct result of improvements in pain. However, there is evidence to suggest that determinants of pain and disability differ. In general, treatments have been more successful at decreasing pain rather than disability. Many of the factors that lead to disability can be improved with exercise. Exercise, both aerobic and strength training, have been examined as treatments for knee osteoarthritis, with considerable variability in the results. The variability between studies may be due to differences in study design, exercise protocols, and participants in the studies. Although there is variability among studies, it is notable that a majority of the studies had a positive effect on pain and or disability. The mechanism of exercise remains unclear and merits future studies to better define a concise, clear exercise protocol that may have the potential for a public health intervention.