Impact of type of meniscal tear on radiographic and symptomatic knee osteoarthritis: a sixteen-year followup of meniscectomy with matched controls

The role of biomaterials in the treatment of meniscal tears

Extensive investigations over the recent decades have established the anatomical, biomechanical and functional importance of the meniscus in the knee joint. As a functioning part of the joint, it serves to prevent the deterioration of articular cartilage and subsequent osteoarthritis. To this end, meniscus repair and regeneration is of particular interest from the biomaterial, bioengineering and orthopaedic research community. Even though meniscal research is previously of a considerable volume, the research community with evolving material science, biology and medical advances are all pushing toward emerging novel solutions and approaches to the successful treatment of meniscal difficulties. This review presents a tactical evaluation of the latest biomaterials, experiments to simulate meniscal tears and the state-of-the-art materials and strategies currently used to treat tears.

In vivo tibiofemoral skeletal kinematics and cartilage contact arthrokinematics during decline walking after isolated meniscectomy

We investigated the effects of isolated meniscectomy on tibiofemoral skeletal kinematics and cartilage contact arthrokinematics in vivo. We recruited nine patients who had undergone isolated medial or lateral meniscectomy, and used a dynamic stereo-radiography (DSX) system to image the patients' knee motion during decline walking. A volumetric model-based tracking process determined 3D tibiofemoral kinematics from the recorded DSX images. Cartilage contact arthrokinematics was derived from the intersection between tibial and femoral cartilage models co-registered to the bones. The kinematics and arthrokinematics were analyzed for early stance and loading response phase (30% of a gait cycle), comparing the affected and intact knees. Results showed that four patients with medial meniscectomy had significantly greater contact centroid excursions in the meniscectomized medial compartments while five patients with lateral meniscectomy had significantly greater cartilage contact area and lateral shift of contact centroid path in the meniscectomized lateral compartments, comparing to those of the same compartments in the contralateral intact knees. No consistent difference however was identified in the skeletal kinematics. The current study demonstrated that cartilage-based intra-articular arthrokinematics is more sensitive and insightful than the skeletal kinematics in assessing the meniscectomy effects.

Association of weight change with progression of meniscal intrasubstance degeneration over 48 months: Data from the Osteoarthritis Initiative

OBJECTIVES

To investigate the association of weight change over 48 months with progression of meniscal intrasubstance degeneration (MID).

METHODS

We studied 487 subjects with MID at baseline and after 48 months using 3-T MRI with the same protocol (FSE sequences with and without fat suppression). These participants lost weight (≥3%, n = 141), had moderate weight gain (3-10%, n = 77), substantial weight gain (>10%, n = 15) or maintained stable weight (n = 254). Progression of MID to a meniscal tear was assessed using the WORMS grading system and compared among weight change groups using logistic regression. ANOVA and chi-square tests were used to study the differences in subjects' characteristics.

RESULTS

Progression of MID increased from weight loss to substantial weight gain (p < 0.001) and was significantly more likely with both moderate weight gain (odds ratio [OR], 4.9; 95% confidence interval [CI] 2.4-8.9) and substantial weight gain (OR, 9.5; 95% CI 3.2-28.5) compared to stable weight. Results were similar in both menisci for moderate weight gain (medial: OR, 6.8; 95% CI 3.5-11.3; lateral: OR, 2.6; 95% CI 1.1-6.6) and substantial weight gain (medial: OR, 21.0; 95% CI 5.1-80.7; lateral: OR, 9.7; 95% CI 0.95-100.2).

CONCLUSION

Weight gain is associated with an increased likelihood that meniscal intrasubstance degeneration will progress with the risk increasing with greater weight gain.

KEY POINTS

• Subjects who gained weight were more likely to develop meniscal tears. • Greater amount of weight gain was associated with an increasing likelihood of progression. • Prevention of weight gain has health benefits for the meniscus.

Dynamic compression of human and ovine meniscal tissue compared with a potential thermoplastic elastomer hydrogel replacement

Understanding how human meniscal tissue responds to loading regimes mimetic of daily life as well as how it compares to larger animal models is critical in the development of a functionally accurate synthetic surrogate. Seven human and eight ovine cadaveric meniscal specimens were regionally sectioned into cylinders 5 mm in diameter and 3 mm thick along with 10 polystyrene-b-polyethylene oxide block copolymer-based thermoplastic elastomer (TPE) hydrogels. Samples were compressed to 12% strain at 1 Hz for 5000 cycles, unloaded for 24 h, and then retested. No differences were found within each group between test one and test two. Human and ovine tissue exhibited no regional dependency (p < 0.05). Human samples relaxed quicker than ovine tissue or the TPE hydrogel with modulus values at cycle 50 not significantly different from cycle 5000. Ovine menisci were found to be similar to human menisci in relaxation profile but had significantly higher modulus values (3.44 MPa instantaneous and 0.61 MPa after 5000 cycles compared with 1.97 and 0.11 MPa found for human tissue) and significantly different power law fit coefficients. The TPE hydrogel had an initial modulus of 0.58 MPa and experienced less than a 20% total relaxation over the 5000. Significant differences in the magnitude of compressive modulus between human and ovine menisci were observed, however the relaxation profiles were similar. Although statistically different than the native tissues, modulus values of the TPE hydrogel material were similar to those of the human and ovine menisci, making it a material worth further investigation for use as a synthetic replacement. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2722-2728, 2017.

Inappropriate use of arthroscopic meniscal surgery in degenerative knee disease

Background and purpose - Current evidence suggests that arthroscopic knee surgery has no added benefit compared with non-surgical management in degenerative meniscal disease. Yet in many countries, arthroscopic partial meniscectomy (APM) remains among the most frequently performed surgeries. This study quantifies and characterizes the dynamics of the current use of knee arthroscopies in Switzerland in a distinctively non-traumatic patient group. Methods - We assessed a non-accident insurance plan of a major Swiss health insurance company for surgery rates of APM, arthroscopic debridement and lavage in patients over the age of 40, comparing the years 2012 and 2015. Claims were analyzed for prevalence of osteoarthritis, related interventions and the association of surgery with insurance status. Results - 648,708 and 647,808 people were examined in 2012 and 2015, respectively. The incidence of APM, debridement, and lavage was 388 per 10⁵ person-years in 2012 and 352 per 10⁵ person-years in 2015 in non-traumatic patients over the age of 40, consisting mostly of APM (96%). Between years, APM surgery rates changed in patients over the age of 65 (p < 0.001) but was similar in patients aged 40-64. Overall prevalence of osteoarthritis was 25%. Insurance status was independently associated with arthroscopic knee surgery. Interpretation - APM is widely used in non-traumatic patients in Switzerland, which contrasts with current evidence. Many procedures take place in patients with degenerative knee disease. Surgery rates were similar in non-traumatic middle-aged patients between 2012 and 2015. Accordingly, the potential of inappropriate use of APM in non-traumatic patients in Switzerland is high.

In Vivo Tibial Cartilage Strains in Regions of Cartilage-to-Cartilage Contact and Cartilage-to-Meniscus Contact in Response to Walking

BACKGROUND

There are currently limited human in vivo data characterizing the role of the meniscus in load distribution within the tibiofemoral joint. Purpose/Hypothesis: The purpose was to compare the strains experienced in regions of articular cartilage covered by the meniscus to regions of cartilage not covered by the meniscus. It was hypothesized that in response to walking, tibial cartilage covered by the meniscus would experience lower strains than uncovered tibial cartilage.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Magnetic resonance imaging (MRI) of the knees of 8 healthy volunteers was performed before and after walking on a treadmill. Using MRI-generated 3-dimensional models of the tibia, cartilage, and menisci, cartilage thickness was measured in 4 different regions based on meniscal coverage and compartment: covered medial, uncovered medial, covered lateral, and uncovered lateral. Strain was defined as the normalized change in cartilage thickness before and after activity.

RESULTS

Within each compartment, covered cartilage before activity was significantly thinner than uncovered cartilage before activity ( P < .001). After 20 minutes of walking, all 4 regions experienced significant cartilage thickness decreases ( P < .01). The covered medial region experienced significantly less strain than the uncovered medial region ( P = .04). No difference in strain was detected between the covered and uncovered regions in the lateral compartment ( P = .40).

CONCLUSION

In response to walking, cartilage that is covered by the meniscus experiences lower strains than uncovered cartilage in the medial compartment. These findings provide important baseline information on the relationship between in vivo tibial compressive strain responses and meniscal coverage, which is critical to understanding normal meniscal function.

Intra-Articular Injections of Autologous Conditioned Serum to Treat Pain from Meniscal Lesions

Routine use of biological therapies is in its early stages. Techniques involve stem cells, platelet preparations, recombinant growth factors and autologous conditioned serum, often combined with surgery. The objective of this case analysis was to document effects of intra-articular autologous conditioned serum injections in outpatients with knee pain associated with meniscal defects. Autologous conditioned serum was prepared from patients’ blood by centrifugal separation from cellular components using a specialized device (EOT ^® II, Orthokine). Outpatients (n=47) with heterogeneous knee meniscus lesions (76.6% traumatic knee injury) were injected once weekly (average 5.2 applications). Average age was 48.6 years (range 21–79). Oxford Knee Score and structural changes with the MRI Boston Leeds Osteoarthritis Knee Score were documented at baseline and 6 months. All analyses were performed retrospectively.

In 83% patients, surgery was avoided during the 6-month observation period. Oxford Knee Score improved significantly from 29.1–44.3 (p<0.001; best possible score=48). Structural findings on MRI, measured by Boston Leeds Osteoarthritis Knee Score, showed significant improvement at 6 months (0.82–0.71, p<0.001). This retrospective study implies that intra-articular autologous conditioned serum injection may be an effective treatment option for knee pain associated with meniscal lesions. Controlled studies of autologous conditioned serum treatment for meniscal lesions are advocated.

[Indication and limitations of meniscus replacement]

BACKGROUND

Meniscal lesions are among the most important musculoskeletal disorders and are the most common indication for knee joint arthroplasty. However, the structural integrity and function is rarely retained, and a loss of tissue results. Thus, there is a huge demand for meniscal replacement options.

CURRENT PROCEDURES

Autografts were used in the past but did not fulfill expectations. Meniscus allografts have been developed to be a viable treatment option. However, availability is limited and evidence of a long-term chondroprotective effect scarce. Artificial scaffolds made from either collagen or PCU foam are available, which aid the regeneration of meniscal tissue and are rather intended as a partial replacement with an intact peripheral rim. Those implants thus have a limited spectrum of indication. While they seem to be symptomatically effective, it remains unclear whether they can reduce secondary cartilage damage. Newer developments aim at a permanent replacement of lost meniscal tissue.

LIMITATIONS

In summary, there is currently no meniscal replacement available for a broad range of indications and with a solid scientific foundation. Prophylactic use should be limited to cases with a high chance of progression to osteoarthritis, like a lateral total meniscectomy. Otherwise meniscal replacement should be considered in younger, symptomatic patients with mild to moderate secondary changes. Potential causes of the initial meniscal injury like instability or deformities should be carefully assessed and addressed. In many cases, osteotomy might be a viable alternative to meniscus replacement.

Self-reported knee pain and disability among healthy individuals: reference data and factors associated with the Knee injury and Osteoarthritis Outcome Score (KOOS) and KOOS-Child

OBJECTIVE

To develop normative reference data for the Knee injury and Osteoarthritis Outcome Score (KOOS) and KOOS-Child, as well as investigate socio-demographic, psychological and physical factors associated with knee pain and disability among healthy adults.

METHOD

The KOOS or KOOS-Child (each containing five subscales) was administered to participants aged 8-101 years within the 1000 Norms Project, an observational study of 1000 self-reported healthy individuals. Self-efficacy, physical activity, body mass index (BMI), lower limb alignment, knee frontal plane projection angle (FPPA), knee range of motion (ROM), knee and hip strength, six-minute walk, 30-second chair stand and timed up and down stairs tests were collected. KOOS data were dichotomised using established cut-off scores and logistic regression analyses were conducted for each subscale.

RESULTS

Socio-demographic characteristics were similar to the Australian population. Normative reference data were generated for children (8-17 years) and adults (18-101 years). Female adults were up to twice as likely to report knee pain, symptoms and sport/recreation (Sport/Rec) limitations compared to males (P < .05). Older age, lower self-efficacy, greater BMI, varus lower limb alignment, lower knee flexion ROM and lower hip external rotation (ER) strength were independently associated with knee pain and disability among adults.

CONCLUSIONS

Age- and gender-stratified reference data for the KOOS and KOOS-Child have been developed to guide interpretation of results in practice and research for individuals with knee disorders. Psychological and physical factors are linked with self-reported knee pain/disability among adults, and longitudinal studies to investigate causation are required.

Predicting knee osteoarthritis risk in injured populations

BACKGROUND

Individuals who suffered a lower limb injury have an increased risk of developing knee osteoarthritis. Early diagnosis of osteoarthritis and the ability to track its progression is challenging. This study aimed to explore links between self-reported knee osteoarthritis outcome scores and biomechanical gait parameters, whether self-reported outcome scores could predict gait abnormalities characteristic of knee osteoarthritis in injured populations and, whether scores and biomechanical outcomes were related to osteoarthritis severity via Spearman's correlation coefficient.

METHODS

A cross-sectional study was conducted with asymptomatic participants, participants with lower-limb injury and those with medial knee osteoarthritis. Spearman rank determined relationships between knee injury and outcome scores and hip and knee kinetic/kinematic gait parameters. K-Nearest Neighbour algorithm was used to determine which of the evaluated parameters created the strongest classifier model.

FINDINGS

Differences in outcome scores were evident between groups, with knee quality of life correlated to first and second peak external knee adduction moment (0.47, 0.55). Combining hip and knee kinetics with quality of life outcome produced the strongest classifier (1.00) with the least prediction error (0.02), enabling classification of injured subjects gait as characteristic of either asymptomatic or knee osteoarthritis subjects. When correlating outcome scores and biomechanical outcomes with osteoarthritis severity only maximum external hip and knee abduction moment (0.62, 0.62) in addition to first peak hip adduction moment (0.47) displayed significant correlations.

INTERPRETATION

The use of predictive models could enable clinicians to identify individuals at risk of knee osteoarthritis and be a cost-effective method for osteoarthritis screening.

Conservative management of a traumatic meniscal injury utilising osteopathy and exercise rehabilitation: A case report

Meniscal injury is one of the most common knee soft tissue injuries, commonly affecting young athletes and an older, degenerative population. Treatment largely depends on the type and extent of the injury with arthroscopic repair or meniscectomy being mainstays. Although non-surgical approaches have been described, there is no published literature regarding a combination of indirect osteopathic techniques and rehabilitation in the management of these injuries. The current case report follows a 20-year-old male presenting with a 5-day history of acute knee pain, following trauma during an Australian Rules Football (AFL) match. An 8-week management plan of indirect osteopathic techniques and a tailored rehabilitation program was implemented. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Lower Extremity Functional Scale (LEFS) questionnaires were utilised to measure outcomes. After the 8-week treatment and rehabilitation program, the patient had exceeded the minimum detectable change score for all outcome measures. This case report suggests that osteopathic manipulative treatment and rehabilitation may be an alternative, non-surgical approach in the management of post-traumatic meniscal injuries.

Knee Biomechanics During Jogging After Arthroscopic Partial Meniscectomy: A Longitudinal Study

BACKGROUND

Altered knee joint biomechanics is thought to play a role in the pathogenesis of knee osteoarthritis and has been reported in patients after arthroscopic partial meniscectomy (APM) while performing various activities. Longitudinally, understanding knee joint biomechanics during jogging may assist future studies to assess the implications of jogging on knee joint health in this population.

PURPOSE

To investigate knee joint biomechanics during jogging in patients 3 months after APM and a healthy control group at baseline and 2 years later at follow-up.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seventy-eight patients who underwent medial APM and 38 healthy controls underwent a 3-dimensional motion analysis during barefoot overground jogging at baseline. Sixty-four patients who underwent APM and 23 controls returned at follow-up. External peak moments (flexion and adduction) and the peak knee flexion angle during stance were evaluated for the APM leg, non-APM leg (nonoperated leg), and control leg.

RESULTS

At baseline, the peak knee flexion angle was 1.4° lower in the APM leg compared with the non-APM leg ( P = .03). No differences were found between the moments in the APM leg compared with the control leg (all P > .05). However, the normalized peak knee adduction moment was 35% higher in the non-APM leg compared with the control leg ( P = .008). In the non-APM leg, the normalized peak knee adduction and flexion moments were higher compared with the APM leg by 16% and 10%, respectively, at baseline ( P ≤ .004). Despite the increase in the peak knee flexion moment in the APM leg compared with the non-APM leg ( P < .001), there were no differences in the peak knee flexion moment or any other parameter assessed at 2-year follow-up between the legs ( P > .05).

CONCLUSION

Comparing the APM leg and control leg, no differences in knee joint biomechanics during jogging for the variables assessed were observed. Higher knee moments in the non-APM leg may have clinical implications for the noninvolved leg. Kinematic differences were small (~1.4°) and therefore of questionable clinical relevance.

CLINICAL RELEVANCE

These results may facilitate future clinical research regarding the implications of jogging on knee joint health in middle-aged, overweight patients after APM.

Risk factors for radiographic joint space narrowing and patient reported outcomes of post-traumatic osteoarthritis after ACL reconstruction: Data from the MOON cohort

The Multicenter Orthopaedic Outcomes Network (MOON) is an NIH-funded prospective, longitudinal cohort of over 3,500 patients who have undergone anterior cruciate ligament reconstruction (ACLR) by 14 sports medicine surgeons at 7 academic medical centers. Patient reported outcome questionnaires (PRO's) are completed at baseline and multiple timepoints after surgery, and a nested cohort of patients return for radiographs to assess the development of joint space changes. We review the risk factors for worse patient reported outcomes, the predictors of clinically significant symptoms of post-traumatic osteoarthritis (PTOA), and the factors associated with more radiographic joint space narrowing. Baseline PRO's were highly predictive of follow-up scores. Factors associated with worse PRO's at 2 and 6 years included female sex, higher BMI, smoking, less education, allograft, medial meniscectomy, or repair, and chondral injury. Partial lateral meniscectomy was unexpectedly associated with better PRO's. Factors associated with clinically significant symptoms of PTOA at 2 and 6 years included subsequent surgery, meniscal pathology, and chondral injury. Factors associated with narrower medial compartment joint space width included medial meniscectomy, medial meniscus repair, and increased age. Medial joint space width was slightly wider overall for the ACLR knees compared to the contralateral normal knees. Future studies will evaluate PRO's and radiographs at 10-year follow-up. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1366-1374, 2017.

The Prevalence of Meniscal Pathology in Asymptomatic Athletes

BACKGROUND

Meniscal pathology is a commonly seen orthopedic condition that can affect a wide age range of patients. Athletes subject their menisci to an increased amount of stress during their careers and may increase their risk of meniscal pathology.

OBJECTIVE

The purpose of this systematic review is to evaluate the prevalence of isolated meniscal pathology in asymptomatic athletes.

METHODS

A systematic review was undertaken to determine the prevalence of meniscal pathology in asymptomatic athletes. A search of multiple databases was conducted. Recreational and higher-level athletes were included. Fourteen articles including 295 athletes (208 male, 87 female) were identified for inclusion (age range 14-66 years, mean 31.2 years). Meniscal pathology was visualized with magnetic resonance imaging and graded on a 1-4 scale (grades 1 and 2 indicating intrasubstance damage, grades 3 and 4 indicating a tear).

RESULTS

There was an overall prevalence of 27.2 % (105/386) of knees with intrasubstance meniscal damage (grades 1 and 2), and 3.9 % (15/386) of knees with a tear (grades 3 and 4). When athletes were split into those who participate in pivoting sports versus non-pivoting sports, pivoting athletes showed an overall prevalence of 15.3 % (31/202) of knees with intrasubstance meniscal pathology and 2.5 % (5/202) of knees with a tear. Non-pivoting athletes showed a prevalence of 54.5 % (61/112) of knees with intrasubstance meniscal pathology and 5.4 % (6/112) of knees with a tear.

CONCLUSION

The overall prevalence of isolated meniscal pathology in asymptomatic athletes was 31.1 % (27.2 % with intrasubstance meniscal damage and 3.9 % with a meniscal tear). More studies of age-comparable, non-athletic populations are necessary for direct comparison with these groups.

Long-term assessment of meniscal extrusion after meniscal repair

BACKGROUND

Arthroscopic meniscal repair limits the medium-term risk of radiological osteoarthritis. Magnetic resonance imaging (MRI) cannot provide an accurate assessment of meniscal healing but may show harbingers of osteoarthritis such as meniscal extrusion. The objective of this study was to assess long-term meniscal extrusion after meniscal repair.

HYPOTHESIS

Arthroscopic meniscal suture is not followed by meniscal extrusion and can, therefore, provide good knee function in the long-term.

METHODS

Consecutive patients who underwent arthroscopic meniscal suture on a stable or stabilised knee were included retrospectively. MRI was performed to measure absolute meniscal extrusion (AME), relative meniscal extrusion (RME), anterior sagittal extrusion (ASE), posterior sagittal extrusion (PSE), coronal cartilage coverage index (cCCI), and sagittal cartilage coverage index (sCCI).

RESULTS

After a mean follow-up of 8.8±0.87 years, there was no evidence of meniscal extrusion in these patients with stable or stabilised knees: AME, 1.7±1.03 and 2.3±0.93mm, RME, 17±0.10% and 28±0.12%, ASE, 2.52±1.43 and 1.71±2.42mm, PSE, 0.29±3.49 and 0.22±2.35mm, cCCI, 23±0.08% and 20±0.09%, and sCCI, 49±0,10% and 53±0.09%.

CONCLUSION

In the long-term after meniscal repair, osteoarthritis is limited and meniscal function seems preserved.

LEVEL OF EVIDENCE

IV, retrospective study.

Are Bone Bruise Characteristics and Articular Cartilage Pathology Associated with Inferior Outcomes 2 and 6 Years After Anterior Cruciate Ligament Reconstruction?

Objective To determine (1) if bone bruise characteristics seen on magnetic resonance imaging are associated with patient-reported outcomes prior to and following anterior cruciate ligament reconstruction and (2) if the combined presence of bone bruises with articular cartilage pathology results in inferior 2- or 6-year outcomes. Design Bone bruise volume and severity were measured on 81 patients' preoperative magnetic resonance imaging in the medial and lateral femoral condyle (MFC, LFC) and medial and lateral tibial plateau (MTP, LTP) using the Costa-Paz classification and a modified version of Roemer and Bohndorf's technique. The relationships between bone bruise volume and severity with Knee Injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) scores were assessed, and pre- and postoperative KOOS and IKDC scores were compared between those with bone bruises either with or without combined local articular cartilage pathology. Results All 81 patients had a bone bruise in at least 1 region and 70 (86%) had bone bruises in ≥2 regions. LTP bruises were the most common (76/81, 94%), followed by the LFC (66, 81%), MTP (46, 57%), and MFC (20, 25%). Neither bone bruise volume nor severity was associated with inferior postoperative outcomes. The subset of 17 patients with bone bruises and combined articular cartilage pathology were 3.4 times more likely to be symptomatic at 6-year follow-up than those without articular cartilage pathology ( P = 0.04). Conclusions The volume and severity of preoperative bone bruises alone were not associated with 2- or 6-year outcomes; however, bone bruises combined with local articular cartilage pathology appear to be more symptomatic after ACL reconstruction.

The Influence of Knee Pain Location on Symptoms, Functional Status, and Knee-related Quality of Life in Older Adults With Chronic Knee Pain: Data From the Osteoarthritis Initiative

OBJECTIVE

To evaluate whether knee pain location can influence symptoms, functional status, and knee-related quality of life in older adults with chronic knee pain.

MATERIALS AND METHODS

A total of 2959 painful knees from the Osteoarthritis Initiative database were analyzed. Trained interviewers recorded patient-reported location of knee pain. Painful knees were divided into 3 groups of patellofemoral only pain, tibiofemoral only pain, and combined pain. Self-reported knee-specific symptoms, functional status, and knee-related quality of life were assessed using the Knee Injury and Osteoarthritis Outcome Score.

RESULTS

The most common knee pain pattern was tibiofemoral only pain (62%), followed by patellofemoral only pain (23%), and combined pain (15%). The combined pain pattern was associated with greater odds of reporting pain, symptoms, sports, or recreational activity limitations and lower knee-related quality of life compared with either isolated knee pain patterns, after adjusting for demographics and radiographic disease severity. Individual item analysis further revealed that patients with combined pain had greater odds of reporting difficulty with daily weight-bearing activities that required knee bending compared with tibiofemoral or patellofemoral only pain patterns. Furthermore, symptoms, functional status, and knee-related quality of life were comparable between patients with patellofemoral and tibiofemoral only pain patterns, after adjusting for demographics and radiographic disease severity.

DISCUSSION

Combined patellofemoral and tibiofemoral pain is associated with poorer clinical presentation compared with isolated knee pain from either location. In addition, patellofemoral pain in isolation may be as important as tibiofemoral pain in causing symptoms and functional limitation in older adults with chronic knee pain.

Value of History, Physical Examination, and Radiographic Findings in the Diagnosis of Symptomatic Meniscal Tear Among Middle-Aged Subjects With Knee Pain

OBJECTIVE

To evaluate the utility of clinical history, radiographic findings, and physical examination findings in the diagnosis of symptomatic meniscal tear (SMT) in patients over age 45 years, in whom concomitant osteoarthritis is prevalent.

METHODS

In a cross-sectional study of patients from 2 orthopedic surgeons' clinics, we assessed clinical history, physical examination findings, and radiographic findings in patients age >45 years with knee pain. The orthopedic surgeons rated their confidence that subjects' symptoms were due to meniscal tear; we defined the diagnosis of SMT as at least 70% confidence. We used logistic regression to identify factors independently associated with diagnosis of SMT, and we used the regression results to construct an index of the likelihood of SMT.

RESULTS

In 174 participants, 6 findings were associated independently with the expert clinician having ≥70% confidence that symptoms were due to meniscal tear: localized pain, ability to fully bend the knee, pain duration <1 year, lack of varus alignment, lack of pes planus, and absence of joint space narrowing on radiographs. The index identified a low-risk group with 3% likelihood of SMT.

CONCLUSION

While clinicians traditionally rely upon mechanical symptoms in this diagnostic setting, our findings did not support the conclusion that mechanical symptoms were associated with the expert's confidence that symptoms were due to meniscal tear. An index that includes history of localized pain, full flexion, duration <1 year, pes planus, varus alignment, and joint space narrowing can be used to stratify patients according to their risk of SMT, and it identifies a subgroup with very low risk.

Changes in Contact Area in Meniscus Horizontal Cleavage Tears Subjected to Repair and Resection

PURPOSE

To assess the changes in tibiofemoral contact pressure and contact area in human knees with a horizontal cleavage tear before and after treatment.

METHODS

Ten human cadaveric knees were tested. Pressure sensors were placed under the medial meniscus and the knees were loaded at twice the body weight for 20 cycles at 0°, 10°, and 20° of flexion. Contact area and pressure were recorded for the intact meniscus, the meniscus with a horizontal cleavage tear, after meniscal repair, after partial meniscectomy (single leaflet), and after subtotal meniscectomy (double leaflet).

RESULTS

The presence of a horizontal cleavage tear significantly increased average peak contact pressure and reduced effective average tibiofemoral contact area at all flexion angles tested compared with the intact state (P < .03). There was approximately a 70% increase in contact pressure after creation of the horizontal cleavage tear. Repairing the horizontal cleavage tear restored peak contact pressures and areas to within 15% of baseline, statistically similar to the intact state at all angles tested (P < .05). Partial meniscectomy and subtotal meniscectomy significantly increased average peak contact pressure and reduced average contact area at all degrees of flexion compared with the intact state (P < .05).

CONCLUSIONS

The presence of a horizontal cleavage tear in the medial meniscus causes a significant reduction in contact area and a significant elevation in contact pressure. These changes may accelerate joint degeneration. A suture-based repair of these horizontal cleavage tears returns the contact area and contact pressure to nearly normal, whereas both partial and subtotal meniscectomy lead to significant reductions in contact area and significant elevations in contact pressure within the knee. Repairing horizontal cleavage tears may lead to improved clinical outcomes by preserving meniscal tissue and the meniscal function.

CLINICAL RELEVANCE

Understanding contact area and peak contact pressure resulting from differing strategies for treating horizontal cleavage tears will allow the surgeon to evaluate the best strategy for treating his or her patients who present with this meniscal pathology.

The effect of patient, provider and surgical factors on survivorship of high tibial osteotomy to total knee arthroplasty: a population-based study

PURPOSE

The aim of this study was to identify the survivorship of high tibial osteotomy (HTO) to total knee arthroplasty (TKA) on a population level, and identify the patient, provider and surgical factors that influenced eventual TKA.

METHODS

Administrative records from physician billings and hospital admissions were used to identify all adults in Ontario, Canada, who underwent an HTO from 1994 to 2010. The primary outcome was time to TKA, which was estimated using Kaplan-Meier (KM) survival analysis. A Cox proportional hazards model examined the risk associated with patient factors (age, sex, income and co-morbidity score), provider factors (hospital status, surgeon volume and surgeon year in practice) and surgical factors (concurrent ligament reconstruction or bone grafting; and previous chondral or meniscal surgery).

RESULTS

A total of 2671 patients who underwent HTO met inclusion. The median age was 46 years (interquartile range 39-53 years), and 62 % were male. The KM survivorship of HTO to TKA at 10 years was 0.67 ± 0.01. Older age [HR 1.05 (95 % CI 1.04, 1.06), p < 0.001; 5 % increased risk for each year over age 46], female sex [HR 1.35 (95 % CI 1.17, 1.55), p < 0.001], higher comorbidity score [HR 1.58 (95 % CI 1.12, 2.22), p = 0.009] and a prior history of arthroscopy/meniscectomy [HR 1.24 (95 % CI 1.08, 1.43), p = 0.002] increased the risk of eventual TKA. However, HTO with concurrent ligament reconstruction was associated with lower [HR 0.62 (95 % CI 0.43, 0.88), p = 0.008] risk of eventual TKA.

CONCLUSION

In this population, two-thirds of patients were able to avoid a TKA for 10 years after HTO. Specific factors such as older age, female sex, higher comorbidity and prior meniscectomy lowered survival rates. An understanding of patient risk factors for conversion to TKA may help guide surgeons in their selection of patients who will benefit most from HTO.

LEVEL OF EVIDENCE

Retrospective cohort study, III.

Knee morphometric and alignment measurements with MR imaging in young adults with central cartilage lesions of the patella and trochlea

PURPOSE

The goal of this study was to assess whether common measurements of patellar and trochlear morphology and patellar alignment are associated with central cartilage lesions of the patella and trochlea using magnetic resonance imaging (MRI).

METHODS

The MRI examinations of 58 patients (38 women, 20 men; mean age, 28.59 years [range: 19-35 years]) with central cartilage lesions of the patella and trochlea were retrospectively compared to those obtained in 102 control subjects (57 women, 45 men; mean age, 27.05 years [range: 20-35 years]). Patients had Modified Noyes Classification grade IIA, IIB or III cartilage defects whereas control subjects had normal MRI examination of the knee as determined by two radiologists. Patellar measurements of facet asymmetry, patellar tilt, lateral patellofemoral angle, Insall-Salvati ratio, and patellotrochlear cartilage overlap were performed in patients and control subjects along with trochlear measurements of the trochlear depth and width, and sulcal angle. Multivariate logistic regression adjusted for age and body mass index was used to assess associations.

RESULTS

The ratio of the lengths of the medial to lateral facets of the patella (OR=2.7×10^-3; P<0.001), angle of the median eminence of the patella (OR=1.05; P=0.040), lateral patellofemoral angle (OR=0.91; P=0.048), Insall-Salvati ratio (OR=364.4; P<0.001) and edema in the superolateral aspect of Hoffa's fat pad (OR=6.52; P<0.001) were significantly associated with central cartilage lesions of the patella and trochlea.

CONCLUSION

Central cartilage lesions of the patellofemoral joint are associated with patellar and trochlear morphology, and patellar alignment.

Cell-Based Meniscus Repair and Regeneration: At the Brink of Clinical Translation?: A Systematic Review of Preclinical Studies

Background:

Meniscus damage can be caused by trauma or degeneration and is therefore common among patients of all ages. Repair or regeneration of the menisci could be of great importance not only for pain relief or regaining function but also to prevent degenerative disease and osteoarthritis. Current treatment does not offer consistent long-term improvement. Although preclinical research focusing on augmentation of meniscal tear repair and regeneration after meniscectomy is encouraging, clinical translation remains difficult.

Purpose:

To systematically evaluate the literature on in vivo meniscus regeneration and explore the optimal cell sources and conditions for clinical translation. We aimed at thorough evaluation of current evidence as well as clarifying the challenges for future preclinical and clinical studies.

Study Design:

Systematic review.

Methods:

A search was conducted using the electronic databases of MEDLINE, Embase, and the Cochrane Collaboration. Search terms included meniscus, regeneration, and cell-based.

Results:

After screening 81 articles based on title and abstract, 51 articles on in vivo meniscus regeneration could be included; 2 additional articles were identified from the references. Repair and regeneration of the meniscus has been described by intra-articular injection of multipotent mesenchymal stromal (stem) cells from adipose tissue, bone marrow, synovium, or meniscus or the use of these cell types in combination with implantable or injectable scaffolds. The use of fibrochondrocytes, chondrocytes, and transfected myoblasts for meniscus repair and regeneration is limited to the combination with different scaffolds. The comparative in vitro and in vivo studies mentioned in this review indicate that the use of allogeneic cells is as successful as the use of autologous cells. In addition, the implantation or injection of cell-seeded scaffolds increased tissue regeneration and led to better structural organization compared with scaffold implantation or injection of a scaffold alone. None of the studies mentioned in this review compare the effectiveness of different (cell-seeded) scaffolds.

Conclusion:

There is heterogeneity in animal models, cell types, and scaffolds used, and limited comparative studies are available. The comparative in vivo research that is currently available is insufficient to draw strong conclusions as to which cell type is the most promising. However, there is a vast amount of in vivo research on the use of different types of multipotent mesenchymal stromal (stem) cells in different experimental settings, and good results are reported in terms of tissue formation. None of these studies compare the effectiveness of different cell-scaffold combinations, making it hard to conclude which scaffold has the greatest potential.

Recovery of lower extremity muscle strength and functional performance in middle-aged patients undergoing arthroscopic partial meniscectomy

PURPOSE

To investigate lower extremity muscle strength and functional performance before and after arthroscopic partial meniscectomy in middle-aged patients with degenerative meniscal tears. We hypothesized that patients would experience deficiencies in the affected leg at 3 months post-surgery, and that this deficiency would be normalized at 12 months following surgery.

METHODS

Twenty-three patients (46 ± 6.5 years) meniscectomized in 2012 and 2013 were examined for knee extension, knee flexion, and hip abduction maximal isometric muscle strength (iMVC), rate of force development (RFD₂₀₀), and knee function (single-leg hop for distance and single-leg knee bends in 30 s.) before surgery, 3 and 12 months after surgery.

RESULTS

Functional performance, knee extension iMVC and RFD₂₀₀ were impaired in the affected leg compared to the contralateral leg (p < 0.05) prior to surgery. A significant (Knee extension RFD₂₀₀, p = 0.033) or borderline significant improvement was observed in the affected leg compared to the contralateral leg from before to 12 months after surgery in most variables (leg × time interaction, n.s.).

CONCLUSION

Middle-aged patients undergoing surgery for degenerative medial meniscal tears show significant reductions in muscle strength, rapid force production, and functional performance in the leg undergoing surgery compared to the contralateral leg prior to surgery. These deficits in muscle strength and knee function were still present at 3 months post-surgery but were no longer observed at 12 months following surgery.

LEVEL OF EVIDENCE

III.

Articular cartilage status 2 years after arthroscopic ACL reconstruction in patients with or without concomitant meniscal surgery: evaluation with 3.0T MR imaging

PURPOSE

To assess articular cartilage changes in the knee joint as detected on 3.0T MR imaging after 2-year follow-up in patients who underwent arthroscopic anterior cruciate ligament reconstruction (ACLR) with or without concomitant meniscal surgery.

METHODS

A total of twenty-nine patients (mean age 30.3 ± 10 years), who underwent arthroscopic ACLR, received clinical and imaging follow-up at an average of 27.8 ± 4.8 months after surgery. Our patients were divided into two subgroups: eighteen patients with additional meniscal injuries at the time of arthroscopic ACLR who underwent meniscal surgery and eleven patients with intact menisci. The cartilage status of all knees at the time of arthroscopic ACLR was recorded. All patients underwent an MRI scan preoperatively and at follow-up with the same imaging protocol. Cartilage status of all knee compartments was evaluated at the time of follow-up by MR imaging and the ICRS classification.

RESULTS

Deterioration of the cartilage status was found at all knee compartments of our study group, with respect to the number of cartilage defects. The cartilage of the lateral femoral condyle (LFC) was most severely affected, followed by patellar and medial femoral condyle (MFC) cartilage. A statistically significant relation was found between surgery of the medial meniscus and the development of new cartilage defects in LFC (p = 0.01) and MFC (p = 0.03) after adjusting for the site of meniscal surgery. The cartilage of LFC and the status of the medial meniscus were also found to be significantly related (p = 0.04). Partial meniscectomy was found to be associated with an increased incidence of new cartilage defects when compared to either meniscal repair or absence of meniscal surgery, although it was not statistically significant.

CONCLUSION

Development of new cartilage lesions was evident after 2-year follow-up in patients with arthroscopic ACLR as detected by MR imaging. There was a multicompartmental pattern of cartilage involvement, and the lateral compartment was most severely affected. Partial meniscectomy at the time of arthroscopic ACLR could be suggested as an additional risk factor for the progression of chondral lesions.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.

Bracing of the Reconstructed and Osteoarthritic Knee during High Dynamic Load Tasks

PURPOSE

Lateral compartment osteoarthritis accompanied by abnormal knee biomechanics is frequently reported in individuals with knee osteoarthritis after anterior cruciate ligament reconstruction (ACLR). The aim of this study was to evaluate changes in knee biomechanics produced by an adjusted and unadjusted varus knee brace during high dynamic loading activities in individuals with lateral knee osteoarthritis after ACLR and valgus malalignment.

METHODS

Nineteen participants who had undergone ACLR 5 to 20 yr previously and had symptomatic and radiographic lateral knee osteoarthritis with valgus malalignment were assessed. Quantitative motion analysis experiments were conducted during hopping, stair ascent, and descent under three test conditions: (i) no brace, (ii) unadjusted brace with sagittal plane support and neutral frontal plane alignment, and (iii) adjusted brace with sagittal plane support and varus realignment (valgus to neutral). Sagittal, frontal, and transverse plane knee kinematics, external joint moment, and angular impulse data were calculated.

RESULTS

Relative to an unbraced knee, braced conditions significantly increased knee flexion and adduction angles during hopping (P = 0.003 and P = 0.005; respectively), stair ascent (P = 0.003 and P < 0.001, respectively), and descent (P = 0.009 and P < 0.001, respectively). In addition, the brace conditions increased knee flexion (P < 0.001) and adduction (P = 0.001) angular impulses and knee stiffness (P < 0.001) during hopping, as well as increased knee adduction moments during stair ascent (P = 0.008) and flexion moments during stair descent (P = 0.006). There were no significant differences between the adjusted and the unadjusted brace conditions (P > 0.05).

CONCLUSION

A knee brace, with or without varus alignment, can modulate knee kinematics and external joint moments during hopping, stairs ascent, and descent in individuals with predominant lateral knee osteoarthritis after ACLR. Longer-term use of a brace may have implications in slowing osteoarthritis progression.

Hydrogels for precision meniscus tissue engineering: a comprehensive review

The meniscus plays a pivotal role to preserve the knee joint homeostasis. Lesions to the meniscus are frequent, have a reduced ability to heal, and may induce tibiofemoral osteoarthritis. Current reconstructive therapeutic options mainly focus on the treatment of lesions in the peripheral vascularized region. In contrast, few approaches are capable of stimulating repair of damaged meniscal tissue in the central, avascular portion. Tissue engineering approaches are of high interest to repair or replace damaged meniscus tissue in this area. Hydrogel-based biomaterials are of special interest for meniscus repair as its inner part contains relatively high proportions of proteoglycans which are responsible for the viscoelastic compressive properties and hydration grade. Hydrogels exhibiting high water content and providing a specific three-dimensional (3D) microenvironment may be engineered to precisely resemble this topographical composition of the meniscal tissue. Different polymers of both natural and synthetic origins have been manipulated to produce hydrogels hosting relevant cell populations for meniscus regeneration and provide platforms for meniscus tissue replacement. So far, these compounds have been employed to design controlled delivery systems of bioactive molecules involved in meniscal reparative processes or to host genetically modified cells as a means to enhance meniscus repair. This review describes the most recent advances on the use of hydrogels as platforms for precision meniscus tissue engineering.

Clinical and radiographic outcomes of meniscus surgery and future targets for biologic intervention: A review of data from the MOON Group

Meniscus injury and treatment occurred with the majority of anterior cruciate ligament reconstructions (ACLR) in the multicenter orthopedic outcomes (MOON) cohort. We describe the patient-reported outcomes, radiographic outcomes, and predictors of pain from meniscus injuries and treatment in the setting of ACLR. Patient-reported outcomes improve significantly following meniscus repair with ACLR, but differences exist based on the meniscus injury laterally (medial or lateral). Patients undergoing medial meniscus repair have worse patient-reported outcomes and more pain compared to those with uninjured menisci. However, lateral meniscal tears can be repaired with similar outcomes as uninjured menisci. Medial meniscal treatment (meniscectomy or repair) results in a significant loss of joint space at 2 years compared to uninjured menisci. Menisci treated with excision had a greater degree of joint space loss compared to those treated with repair. Clinically significant knee pain is more common following injuries to the medial meniscus and increased in patients who undergo early re-operation after initial ACLR. Future research efforts aimed at improving outcomes after combined ACLR and meniscus treatment should focus on optimizing biologic and mechanical environments that promote healing of medial meniscal tears sustained during ACL injury.

Knee contact forces and lower extremity support moments during running in young individuals post-partial meniscectomy

PURPOSE

While partial meniscectomy results in a compromised tibiofemoral joint, little is known regarding tibiofemoral joint loading during running in individuals who are post-partial meniscectomy. It was hypothesized that individuals post-partial meniscectomy would run with a greater hip support moment, yielding reduced peak knee extension moments and reduced tibiofemoral joint contact forces.

METHODS

3-D Treadmill running mechanics were evaluated in 23 athletic individuals post-partial meniscectomy (37.5 ± 19.0 months post-partial meniscectomy) and 23 matched controls. Bilateral hip, knee and ankle contributions to the total support moment and the peak knee extension moment were calculated. A musculoskeletal model estimated peak and impulse tibiofemoral joint contact forces. Knee function was quantified with the Knee injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

During running, the partial meniscectomy group had a greater hip support moment (p = 0.002) and a reduced knee support moment (p < 0.001) relative to the total support moment. This movement pattern was associated with a 14.5 % reduction (p = 0.019) in the peak knee extension moment. Despite these differences, there were no significant group differences in peak or impulse tibiofemoral joint contact forces. Lower KOOS Quality of Life scores were associated with greater hip support moment (p = 0.004, r = -0.58), reduced knee support moment (p = 0.006, r = 0.55) and reduced peak knee extension moment (p = 0.01, r = 0.52).

CONCLUSIONS

Disordered running mechanics are present long term post-partial meniscectomy. A coordination strategy that shifts a proportion of the total support moment away from the knee to the hip reduces the peak knee extension moment, but does not equate to reduced tibiofemoral joint contact forces during running in individuals post-partial meniscectomy.

LEVEL OF EVIDENCE

III.

Traumatic and Degenerative Meniscus Tears Have Different Gene Expression Signatures

BACKGROUND

Meniscus tears are classified as traumatic or degenerative based on the tear pattern. There is little evidence demonstrating biological differences between the 2 tear types.

HYPOTHESIS

Gene expression signatures in the injured meniscus are different between traumatic (vertical) and degenerative (complex, horizontal, or flap) tears.

STUDY DESIGN

Controlled laboratory study.

METHODS

Samples of the torn meniscus from the white-white zone were removed at the time of clinically indicated partial meniscectomy from 48 patients (37 with degenerative tears and 11 with traumatic tears). mRNA expression in the injured menisci was measured by quantitative real-time polymerase chain reaction for selected molecular markers of osteoarthritis, inflammation, and cartilage homeostasis (eg, cytokines/chemokines, aggrecanases/metalloproteinases, transcription factors, cartilage matrix genes, and adipokines). The tear pattern (traumatic or degenerative) and location (medial or lateral) were recorded for each patient. Gene expression differences between degenerative and traumatic tears were computed after adjusting for patients' age, sex, and body mass index and for location of the resected meniscus (medial/lateral).

RESULTS

Gene expression in meniscus tears varied by pattern. Chemokines ( IL8 [ P < .001] and CXCL6 [ P < .001]) and matrix metalloproteinases ( MMP1 [ P = .011] and MMP3 [ P = .016]) were expressed at a significantly higher level in traumatic tears compared with degenerative tears. In contrast, COL1A1 was expressed at a lower level in traumatic tears compared with degenerative tears ( P = .058). None of the genes tested demonstrated significant differences between medial and lateral meniscus tears.

CONCLUSION

Traumatic meniscus tears overall exhibited a higher inflammatory/catabolic response as evidenced by higher levels of chemokine and matrix metalloproteinase expression than degenerative tears. These findings suggest that there is a (molecular) biological distinction between traumatic and degenerative tears.

CLINICAL RELEVANCE

The catabolic/inflammatory differences between traumatic and degenerative tears may be relevant to treatment decisions regarding the meniscus as well as advance our understanding of how meniscus tears relate to the development of knee osteoarthritis.

Repair of Torn Avascular Meniscal Cartilage Using Undifferentiated Autologous Mesenchymal Stem Cells: From In Vitro Optimization to a First-in-Human Study

Meniscal cartilage tears are common and predispose to osteoarthritis (OA). Most occur in the avascular portion of the meniscus where current repair techniques usually fail. We described previously the use of undifferentiated autologous mesenchymal stem cells (MSCs) seeded onto a collagen scaffold (MSC/collagen‐scaffold) to integrate meniscal tissues in vitro. Our objective was to translate this method into a cell therapy for patients with torn meniscus, with the long‐term goal of delaying or preventing the onset of OA. After in vitro optimization, we tested an ovine‐MSC/collagen‐scaffold in a sheep meniscal cartilage tear model with promising results after 13 weeks, although repair was not sustained over 6 months. We then conducted a single center, prospective, open‐label first‐in‐human safety study of patients with an avascular meniscal tear. Autologous MSCs were isolated from an iliac crest bone marrow biopsy, expanded and seeded into the collagen scaffold. The resulting human‐MSC/collagen‐scaffold implant was placed into the meniscal tear prior to repair with vertical mattress sutures and the patients were followed for 2 years. Five patients were treated and there was significant clinical improvement on repeated measures analysis. Three were asymptomatic at 24 months with no magnetic resonance imaging evidence of recurrent tear and clinical improvement in knee function scores. Two required subsequent meniscectomy due to retear or nonhealing of the meniscal tear at approximately 15 months after implantation. No other adverse events occurred. We conclude that undifferentiated MSCs could provide a safe way to augment avascular meniscal repair in some patients. Registration: EU Clinical Trials Register, 2010‐024162‐22. Stem Cells Translational Medicine2017;6:1237–1248

Three-dimensional reconstructed magnetic resonance scans: Accuracy in identifying and defining knee meniscal tears

AIM

To determine whether three-dimensional (3D) reconstruction from conventional magnetic resonance imaging (MRI) is able to accurately detect a meniscal tear, and define the configuration.

METHODS

Thirty-three patients’ 3T MRI scan data were collected and sagittal uni-planar 3D reconstructions performed from the preoperative MRI. There were 24 meniscal tears in 24 patients, and nine controls. All patients had arthroscopic corroboration of MRI findings. Two independent observers prospectively reported on all 33 reconstructions. Meniscal tear presence or absence was noted, and tear configuration subsequently categorised as either radial, bucket-handle, parrot beak, horizontal or complex.

RESULTS

Identification of control menisci or meniscal tear presence was excellent (Accuracy: observer 1 = 90.9%; observer 2 = 81.8%). Of the tear configurations, bucket handle tears were accurately identified (Accuracy observer 1 and 2 = 80%). The remaining tear configurations were not accurately discernable.

CONCLUSION

Uni-planar 3D reconstruction from 3T MRI knee scan sequences are useful in identifying normal menisci and menisci with bucket-handle tears. Advances in MRI sequencing and reconstruction software are awaited for accurate identification of the remaining meniscal tear configurations.

Epidemiology of intra- and peri-articular structural injuries in traumatic knee joint hemarthrosis - data from 1145 consecutive knees with subacute MRI

OBJECTIVE

In patients with traumatic knee distorsion and hemarthrosis, to investigate the panorama of structural injury, as visualized on magnetic resonance imaging (MRI).

DESIGN

Cohort study of 1145 consecutive patients with traumatic knee distorsion who underwent MRI within median 8 days after injury. We present structural injury as visualized on MRI in relation to age, sex and activity at injury. Population based gender specific annual incidences of common structural injuries were calculated.

RESULTS

The majority of injuries (72%) occurred during sports. Overall, anterior cruciate ligament (ACL) rupture was the most common structural injury (52%), followed by meniscal tear (41%) and lateral patella dislocation (LPD, 17%). Only 12% of ACL tears were isolated with meniscal tear being the most common associated injury (55%). The annual incidence of ACL injury was 77 (70-85, 95% CI) per 100,000 inhabitants with significant differences between men (91, 80-103) and women (63, 53-73). In those aged 16 years and younger, LPD was the most frequent structural injury, both in boys (39%) and girls (43%). In this age group, the annual incidence of LPD was 88 (68-113) and higher in boys (113, 81-154) than in girls (62, 39-95).

CONCLUSIONS

ACL injury occurs in one out of two knees with traumatic hemarthrosis but only 12% are without concomitant structural injury. The overall rate of traumatic knee hemarthrosis and ACL injury is higher in men. In those aged 10-19 years, ACL rupture is more common among girls than boys whereas in those 16 years and younger, LPD is more common among boys than girls.

Exploiting endogenous fibrocartilage stem cells to regenerate cartilage and repair joint injury

Tissue regeneration using stem cell-based transplantation faces many hurdles. Alternatively, therapeutically exploiting endogenous stem cells to regenerate injured or diseased tissue may circumvent these challenges. Here we show resident fibrocartilage stem cells (FCSCs) can be used to regenerate and repair cartilage. We identify FCSCs residing within the superficial zone niche in the temporomandibular joint (TMJ) condyle. A single FCSC spontaneously generates a cartilage anlage, remodels into bone and organizes a haematopoietic microenvironment. Wnt signals deplete the reservoir of FCSCs and cause cartilage degeneration. We also show that intra-articular treatment with the Wnt inhibitor sclerostin sustains the FCSC pool and regenerates cartilage in a TMJ injury model. We demonstrate the promise of exploiting resident FCSCs as a regenerative therapeutic strategy to substitute cell transplantation that could be beneficial for patients suffering from fibrocartilage injury and disease. These data prompt the examination of utilizing this strategy for other musculoskeletal tissues.

Assessing the external validity of algorithms to estimate EQ-5D-3L from the WOMAC

BACKGROUND

The use of mapping algorithms have been suggested as a solution to predict health utilities when no preference-based measure is included in the study. However, validity and predictive performance of these algorithms are highly variable and hence assessing the accuracy and validity of algorithms before use them in a new setting is of importance. The aim of the current study was to assess the predictive accuracy of three mapping algorithms to estimate the EQ-5D-3L from the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) among Swedish people with knee disorders. Two of these algorithms developed using ordinary least squares (OLS) models and one developed using mixture model.

METHODS

The data from 1078 subjects mean (SD) age 69.4 (7.2) years with frequent knee pain and/or knee osteoarthritis from the Malmö Osteoarthritis study in Sweden were used. The algorithms' performance was assessed using mean error, mean absolute error, and root mean squared error. Two types of prediction were estimated for mixture model: weighted average (WA), and conditional on estimated component (CEC).

RESULTS

The overall mean was overpredicted by an OLS model and underpredicted by two other algorithms (P < 0.001). All predictions but the CEC predictions of mixture model had a narrower range than the observed scores (22 to 90 %). All algorithms suffered from overprediction for severe health states and underprediction for mild health states with lesser extent for mixture model. While the mixture model outperformed OLS models at the extremes of the EQ-5D-3D distribution, it underperformed around the center of the distribution.

CONCLUSIONS

While algorithm based on mixture model reflected the distribution of EQ-5D-3L data more accurately compared with OLS models, all algorithms suffered from systematic bias. This calls for caution in applying these mapping algorithms in a new setting particularly in samples with milder knee problems than original sample. Assessing the impact of the choice of these algorithms on cost-effectiveness studies through sensitivity analysis is recommended.

Effect of Knee Extensor Strength on Incident Radiographic and Symptomatic Knee Osteoarthritis in Individuals With Meniscal Pathology: Data From the Multicenter Osteoarthritis Study

OBJECTIVE

High knee extensor strength may be important to protect against the development of knee osteoarthritis (OA) in populations at elevated risk, such as individuals with meniscal pathology. We investigated the extent to which high knee extensor muscle strength was associated with a decreased risk of developing radiographic or symptomatic knee OA in individuals with medial meniscal pathology.

METHODS

We studied knees that at the baseline visit of the Multicenter Osteoarthritis Study had medial meniscal pathology but did not have radiographic knee OA (373 knees in 373 participants) or symptomatic knee OA (combination of radiographic knee OA and frequent knee symptoms; 531 knees in 531 participants). Isokinetic knee extensor strength was measured at baseline, and participants were followed for development of incident radiographic knee OA or incident symptomatic knee OA at 84 months. Separate binomial regression analyses with robust SEs adjusted for age, history of knee surgery, physical activity level, and clinic site were conducted for men and women.

RESULTS

High knee extensor strength (normalized by allometric scaling) was associated with a reduced risk of radiographic knee OA in women (relative risk [RR] 0.52, 95% confidence interval [95% CI] 0.29-0.94) but not in men (RR 0.56, 95% CI 0.27-1.16). High knee extensor strength did not protect against the development of symptomatic knee OA, either in women or men.

CONCLUSION

The results only partly confirm the hypothesis that high knee extensor muscle strength protects against later development of knee OA in individuals with medial meniscal pathology.

Treatment of Painful, Irreparable Partial Meniscal Defects With a Polyurethane Scaffold: Midterm Clinical Outcomes and Survival Analysis

BACKGROUND

A biodegradable polyurethane scaffold was designed to fulfill a challenging clinical need in the treatment of patients with painful, irreparable partial meniscal defects.

HYPOTHESIS

The use of an acellular polyurethane scaffold for new tissue generation in irreparable, partial meniscal defects provides both midterm pain relief and improved functionality.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 44 patients with irreparable, partial meniscal defects (29 medial and 15 lateral) were implanted with a polyurethane scaffold in a prospective, single-arm proof-of-principle study with a minimum 5-year follow-up. Clinical outcomes were measured with the visual analog scale (VAS) for pain, International Knee Documentation Committee (IKDC), and Knee injury and Osteoarthritis Outcome Score (KOOS) at baseline and at 2- and 5-year follow-up. Magnetic resonance imaging (MRI) was used to evaluate the meniscal implant and cartilage status of the index compartment. Kaplan-Meier time-to-treatment failure distributions were also performed. Removal of the scaffold, conversion to a meniscal transplant, or unicompartmental/total knee arthroplasty was used as endpoints.

RESULTS

Seven patients were lost to follow-up (15.9%). The patients who participated in this study showed significant clinical improvement after surgery (mean [±SD] at baseline, 2 years, and 5 years: 56.2 ± 21.6, 24.6 ± 22.7, and 19.3 ± 26.9, respectively [VAS]; 206.5 ± 79.7, 329.8 ± 108.9, and 333.6 ± 112.2, respectively [total KOOS]). MRI of the scaffolds showed a smaller sized implant when compared with the native meniscus with an irregular surface at 2- and 5-year follow-up. A stable cartilage status of the index compartment at 5-year follow-up was demonstrated in 46.7% of patients compared with the baseline status. During the follow-up period, 62.2% of the implants survived. At final follow-up, 66.7% of the medial scaffolds were still functioning versus 53.8% of the lateral scaffolds.

CONCLUSION

A polyurethane meniscal implant can improve knee joint function and significantly reduce pain in patients with segmental meniscus deficiency up to 5 years after implantation. A stable cartilage status of the index compartment at 5-year follow-up was demonstrated in 46.7% of patients, calling into question the chondroprotective ability of the implant. In addition, a relatively high failure rate was noticed. Long-term and randomized controlled studies are mandatory to confirm the initial results and the reliability of this procedure.

Arthroscopic meniscectomy of traumatic versus atraumatic tears in middle aged patients: is there a difference?

INTRODUCTION

Meniscal tears can be classified in various ways, one of which is into traumatic or degenerative. It is not known whether partial meniscectomy of clinically defined traumatic compared to degenerative tears in middle age patients has favorable results. The purpose of this study was to compare the outcome after arthroscopic partial meniscectomy of clinically defined traumatic to degenerative meniscal tears in middle age patients.

MATERIALS AND METHODS

Eighty-six middle aged patients with stable knees and no radiographic signs of osteoarthritis who had arthroscopic partial meniscectomy were divided into a study group of 43 patients with a preceding knee injury related to their knee symptoms (traumatic group) and a control group of 43 uninjured patients (atraumatic group), matched by age, sex, body mass index and comorbidities. The surgical findings and postoperative clinical scores were compared between the two groups.

RESULTS

There were no statistical differences in surgical findings of tear types and degree of chondral lesions. At the end of the follow-up 33 (77 %) patients in each group were satisfied to have had the operation. The median Lysholm score improved from 65.9 ± 17.4 to 77.4 ± 21.2 points (P = 0.001) in the traumatic group and from 65.3 ± 17 to 82.4 ± 17.7 in the atraumatic group (P < 0.0001).

CONCLUSIONS

Arthroscopic partial meniscectomy in middle aged patients with stable knees and no signs of radiographic osteoarthritis improve pain and function. There were no differences in surgical findings and short term clinical outcome between patients with and without preceding knee injury.

Association of knee pain and different definitions of knee osteoarthritis with health-related quality of life: a population-based cohort study in southern Sweden

Background

While the impact of knee pain and knee osteoarthritis (OA) on health-related quality of life (HRQoL) has been investigated in the literature, there is a lack of knowledge on the impact of different definitions of OA on HRQoL. The main aim of this study was to measure and compare the impact of knee OA and its different definitions on HRQoL in the general population.

Methods

A random sample of 1300 participants from Malmö, Sweden with pain in one or both knees in the past 12 months with duration ≥4 weeks and 650 participants without were invited to clinical and radiographic knee examination. A total of 1527 individuals with a mean (SD) age 69.4 (7.2) participated and responded to both generic (EQ-5D-3L) and disease-specific (the Knee injury and Osteoarthritis Outcome Score) questionnaires. Knee pain was defined as pain during the last month during most of the days. Knee OA was defined radiographically (equivalent to Kellgren and Lawrence grade ≥2) and clinically according to the American College of Rheumatology (ACR) criteria.

Results

Of participants with either knee pain or knee OA or both, 7 % reported no problem for the EQ-5D-3L attributes. The corresponding proportion among references (neither knee pain nor OA) was 42 %. The participants with knee pain and OA had all HRQoL measures lower compared to those with knee pain but no OA. The ACR clinical definition of knee OA was associated with lower HRQoL than the definition based on radiographic knee OA (adjusted difference −0.08 in UK EQ-5D-3L index score).

Conclusions

Applying different definitions of knee OA result in different levels of HRQoL and this is mainly explained by the knee pain experience. These differences may lead to discrepant conclusions from cost-utility analyses.

The cost-effectiveness of meniscal repair versus partial meniscectomy: A model-based projection for the United States

BACKGROUND

Meniscal tears are the most common knee condition requiring surgery, and represent a substantial disease burden with clinical and cost implications. The success rates partial meniscectomy and meniscal repair have been studied, but limited information is available investigating their long-term costs and effects. Our objective was to assess the long-term cost-effectiveness of meniscal repair compared to meniscectomy.

METHODS

We constructed a decision-analytic Markov disease progression model, using strategy-specific failure rates and treatment-specific probabilities for the development of osteoarthritis (OA) and subsequent knee replacement (TKR). Failure rates and OA incidence were derived from controlled and uncontrolled studies as well as meta-analyses. Costs were derived from 2014U.S. reimbursement amounts and published literature.

RESULTS

Meniscal repair was associated with an increased failure rate (RR of 4.37), but meaningful reductions in OA and TKR incidence (29.7% vs. 39.4% and 19.6% vs. 27.9%, respectively) in our model-based analysis. Over the 30-year horizon, meniscal repair was associated with an increase in discounted QALYs to 16.52 (compared to 16.37 QALYs for meniscectomy), at overall discounted savings of $2384, making it the dominant index procedure strategy. Using age-specific per-patient cost and QALYs projected for the 30-year horizon, our computations suggest that payers could save approximately $43 million annually if 10% of current meniscectomies could be performed as meniscal repairs.

CONCLUSIONS

Our projection suggests that meniscal repair, despite substantially higher failure rates, is associated with improved long-term outcomes and cost savings relative to meniscectomy in the majority of patients, making it the dominant treatment strategy.

Gait Characteristics of People with Lateral Knee Osteoarthritis after ACL Reconstruction

PURPOSE

Lateral knee osteoarthritis (OA) is common after anterior cruciate ligament reconstruction (ACLR), yet gait characteristics associated with lateral knee OA after ACLR are not well understood. This cross-sectional study aimed to compare knee, trunk, pelvis, hip, and ankle kinematics and moments between people with predominant lateral knee OA after ACLR and healthy controls.

METHODS

Nineteen post-ACLR people with lateral knee OA and 25 healthy controls were recruited. Quantitative gait analysis was conducted during walking, and knee pain, confidence, and kinesiophobia were assessed. Between-group differences in peak kinematics and moments were evaluated, and Pearson correlations evaluated relations between biomechanical and patient-reported measures (P < 0.05).

RESULTS

Participants with lateral knee OA after ACLR had greater peak knee flexion (mean difference, 3.5°; 95% confidence interval, 0.9-6.1) and lower knee internal rotation angles (-3.3°; -6.2 to -0.5) than the controls. Those with lateral knee OA also had greater peak pelvic anterior tilt (3.1°, 0.4-5.9), hip flexion angles (5.1°, 1.9-8.3), and peak ankle dorsiflexion moment (0.1 N·m·kg(-1), 0.0-0.2). In the lateral knee OA group, worse knee confidence and kinesiophobia were significantly correlated with greater peak trunk flexion angle (r = 0.654 and r = 0.535, respectively) and greater knee pain was significantly correlated with greater peak knee flexion angle (r = 0.535).

CONCLUSIONS

Gait characteristics associated with lateral knee OA after ACLR differ from those in healthy individuals, predominantly in the sagittal plane. Increased sagittal plane knee and trunk kinematics seem to be related to worse knee pain, confidence, and kinesiophobia. These findings will assist the development of compartment-specific interventions for individuals with posttraumatic lateral knee OA.

Predictors of FIFA 11+ Implementation Intention in Female Adolescent Soccer: An Application of the Health Action Process Approach (HAPA) Model

The Fédération Internationale de Football (FIFA) 11+ warm-up program is efficacious at preventing lower limb injury in youth soccer; however, there has been poor adoption of the program in the community. The purpose of this study was to determine the utility of the Health Action Process Approach (HAPA) behavior change model in predicting intention to use the FIFA 11+ in a sample of 12 youth soccer teams (coaches n = 10; 12–16 year old female players n = 200). A bespoke cross-sectional questionnaire measured pre-season risk perceptions, outcome expectancies, task self-efficacy, facilitators, barriers, and FIFA 11+ implementation intention. Most coaches (90.0%) and players (80.0%) expected the program to reduce injury risk but reported limited intention to use it. Player data demonstrated an acceptable fit to the hypothesized model (standardized root mean square residual (SRMR) = 0.08; root mean square of error of approximation (RMSEA) = 0.06 (0.047–0.080); comparative fit index (CFI) = 0.93; Tucker Lewis index (TLI) = 0.91) Task self-efficacy (β = 0.53, p ≤ 0.01) and outcome expectancies (β = 0.13 p ≤ 0.05) were positively associated with intention, but risk perceptions were not (β = −0.02). The findings suggest that the HAPA model is appropriate for use in this context, and highlight the need to target task self-efficacy and outcome expectancies in FIFA 11+ implementation strategies.

Socioeconomic inequalities in knee pain, knee osteoarthritis, and health-related quality of life: a population-based cohort study in southern Sweden

OBJECTIVES

To determine socioeconomic inequalities in frequent knee pain (FKP), knee osteoarthritis (OA), and associated health-related quality of life (HRQoL) in Sweden.

METHOD

In 2007 a postal questionnaire about knee pain was sent to a random sample of 10 000 residents of Malmö, Sweden (7402 individuals responded). Subjects reporting pain with duration ≥ 4 weeks in one or both knees in the past 12 months were classified as having FKP. A random sample of 1527 subjects with and without FKP attended a clinical and radiographic knee examination and responded to generic and disease-specific HRQoL questionnaires. We used the individuals' level of education and occupation as socioeconomic status (SES) measures, and we calculated the relative index of inequality (RII) using Poisson regression with robust standard errors adjusted for age and gender. We applied weighting to account for a possible selection bias that might arise from non-responses in the study.

RESULTS

With education, the RIIs for FKP and knee OA were 0.71 [95% confidence interval (CI) 0.61-0.84] and 0.56 (95% CI 0.34-0.93), respectively. With occupation, the corresponding figures were 0.70 (95% CI 0.60-0.82) and 0.59 (95% CI 0.37-0.94), respectively. There were socioeconomic gradients in HRQoL in favour of people with better SES. RIIs for FKP and HRQoL but not knee OA were essentially similar after additional adjustment for mediators.

CONCLUSIONS

In Sweden there are socioeconomic gradients related to both FKP and knee OA as well as HRQoL in favour of people with better SES. SES should be taken into account in health resource allocation pertaining to knee-related disorders.

Effect of Matching or Overconstraining Knee Laxity During Anterior Cruciate Ligament Reconstruction on Knee Osteoarthritis and Clinical Outcomes: A Randomized Controlled Trial With 84-Month Follow-up

BACKGROUND

The "initial graft tension" applied at the time of graft fixation during anterior cruciate ligament (ACL) reconstruction surgery modulates joint contact mechanics, which in turn may promote posttraumatic osteoarthritis (OA).

PURPOSE/HYPOTHESES

The study objectives were to compare clinical, functional, patient-reported, and OA imaging outcomes between 2 different initial laxity-based graft tension cohorts and a matched uninjured control group as well as to evaluate the effects of laxity-based graft tension on OA development at 84-month follow-up. The 2 laxity-based tension protocols were (1) to restore normal anteroposterior (AP) laxity at the time of surgery relative to the contralateral uninjured knee (low-tension group) or (2) to overconstrain AP laxity by 2 mm relative to the contralateral uninjured knee (high-tension group). The hypotheses were that (1) the high-tension group would have improved outcomes and decreased OA compared with the low-tension group after 84 months, and (2) the outcomes for the high-tension group would be equivalent to those for an age-, sex-, race-, and activity-matched group of control participants with uninjured knees.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Patients had their ACLs reconstructed with either a bone-patellar tendon-bone or 4-stranded hamstring autograft, and outcomes were compared with a matched control group. Outcomes were evaluated preoperatively and at 60 and 84 months postoperatively and included clinical (KT-1000 arthrometer AP laxity measurement and International Knee Documentation Committee [IKDC] examination score), functional (1-legged hop for distance and knee extensor torque), patient-reported (Knee injury and Osteoarthritis Outcome Score [KOOS], Short Form-36 [SF-36], and patient satisfaction survey), and OA imaging (measurement of joint space width [JSW], Osteoarthritis Research Society International [OARSI] radiographic score, and Whole-Organ Magnetic Resonance Imaging Score [WORMS]) components. Repeated-measures analyses of variance were used to evaluate differences in outcomes between the treatment groups and the control group.

RESULTS

There were significant differences between the 2 tension groups in 1 of 5 KOOS subscales (sports and recreation; P = .04) and 2 of 8 SF-36 subscales (vitality, mental health; P < .04) at 84 and 60 months, respectively. Both tension groups scored significantly worse than the control group in the IKDC examination (P < .001), 1-legged hop (P ≤ .017), KOOS quality of life and symptoms subscales (P < .03), and OARSI radiographic score (P ≤ .02) at 84 months. The low-tension group performed significantly worse than the control group on the KOOS pain subscale (P = .03), SF-36 general health and social functioning (P < .04), OARSI radiographic score (P < .001), and WORMS (P = .001), while the high-tension group had statistically different results than the control group in AP knee laxity (P < .001), radiographic JSW (P = .003), and OARSI radiographic score (P = .02) as well as significantly more subsequent knee injuries (P = .02) at 84 months.

CONCLUSION

The results do not support the hypotheses that the high-tension group would have improved outcomes when compared with the low-tension group after 84 months of healing or that the outcomes for the high-tension group would be equivalent to those for the matched control group. While there were minor differences in patient-reported outcomes between the 2 laxity-based tension groups, all other outcomes were similar.

REGISTRATION

NCT00434837.

Does Anteromedial Portal Drilling Improve Footprint Placement in Anterior Cruciate Ligament Reconstruction?

BACKGROUND

Considerable debate remains over which anterior cruciate ligament (ACL) reconstruction technique can best restore knee stability. Traditionally, femoral tunnel drilling has been done through a previously drilled tibial tunnel; however, potential nonanatomic tunnel placement can produce a vertical graft, which although it would restore sagittal stability, it would not control rotational stability. To address this, some suggest that the femoral tunnel be created independently of the tibial tunnel through the use of an anteromedial (AM) portal, but whether this results in a more anatomic footprint or in stability comparable to that of the intact contralateral knee still remains controversial.

QUESTIONS/PURPOSES

(1) Does the AM technique achieve footprints closer to anatomic than the transtibial (TT) technique? (2) Does the AM technique result in stability equivalent to that of the intact contralateral knee? (3) Are there differences in patient-reported outcomes between the two techniques?

METHODS

Twenty male patients who underwent a bone-patellar tendon-bone autograft were recruited for this study, 10 in the TT group and 10 in the AM group. Patients in each group were randomly selected from four surgeons at our institution with both groups demonstrating similar demographics. The type of procedure chosen for each patient was based on the preferred technique of the surgeon. Some surgeons exclusively used the TT technique, whereas other surgeons specifically used the AM technique. Surgeons had no input on which patients were chosen to participate in this study. Mean postoperative time was 13 ± 2.8 and 15 ± 3.2 months for the TT and AM groups, respectively. Patients were identified retrospectively as having either the TT or AM Technique from our institutional database. At followup, clinical outcome scores were gathered as well as the footprint placement and knee stability assessed. To assess the footprint placement and knee stability, three-dimensional surface models of the femur, tibia, and ACL were created from MRI scans. The femoral and tibial footprints of the ACL reconstruction as compared with the intact contralateral ACL were determined. In addition, the AP displacement and rotational displacement of the femur were determined. Lastly, as a secondary measurement of stability, KT-1000 measurements were obtained at the followup visit. An a priori sample size calculation indicated that with 2n = 20 patients, we could detect a difference of 1 mm with 80% power at p < 0.05. A Welch two-sample t-test (p < 0.05) was performed to determine differences in the footprint measurements, AP displacement, rotational displacement, and KT-1000 measurements between the TT and AM groups. We further used the confidence interval approach with 90% confidence intervals on the pairwise mean group differences using a Games-Howell post hoc test to assess equivalence between the TT and AM groups for the previously mentioned measures.

RESULTS

The AM and TT techniques were the same in terms of footprint except in the distal-proximal location of the femur. The TT for the femoral footprint (DP%D) was 9% ± 6%, whereas the AM was -1% ± 13% (p = 0.04). The TT technique resulted in a more proximal footprint and therefore a more vertical graft compared with intact ACL. The AP displacement and rotation between groups were the same and clinical outcomes did not demonstrate a difference.

CONCLUSIONS

Although the AM portal drilling may place the femoral footprint in a more anatomic position, clinical stability and outcomes may be similar as long as attempts are made at creating an anatomic position of the graft.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Which patients do not return to work after total knee arthroplasty?

Total knee arthroplasty (TKA) is increasingly being performed among working patients suffering from knee osteoarthritis. Two out of ten patients do not return to work (RTW) after TKA. Little evidence is available about these patients to guide clinicians. Therefore, this study investigates patients' characteristics associated with no RTW. A multicenter retrospective cohort study was performed among working patients having undergone a primary TKA during 2005-2010. The following preoperative characteristics were assessed: age at surgery, sex, comorbidity, body mass index (BMI), preoperative sick-leave duration, patient-reported work-relatedness of knee symptoms, and physical job demands. In addition, the Knee injury and Osteoarthritis Outcome Scores (KOOS) after TKA were assessed. Backward stepwise logistic regression analyses were performed to predict no RTW. Seven hundred and sixty-four patients were approached, and 558 patients (73 %) responded. One hundred and sixty-seven met the inclusion criteria and 46 did not RTW. A preoperative sick-leave duration >2 weeks (OR 12.5, 90 % CI 5.0-31.5) was most strongly associated with no RTW. Other associations found were: female sex (OR 3.2, 90 % CI 1.3-8.2), BMI ≥ 30 (OR 2.8, 90 % CI 1.1-7.1), patient-reported work-relatedness of knee symptoms (OR 5.3, 90 % CI 2.0-14.1), and a physically knee-demanding job (OR 3.3, 90 % CI 1.2-8.9). Age and KOOS were not associated with no RTW. Especially obese female workers, with a preoperative sick-leave duration >2 weeks, who perform knee-demanding work and indicate that their knee symptoms are work-related have a high chance for no RTW after TKA. These results stress the importance of a more timely referral for work-directed care of patients at risk for no RTW after TKA.

Knee Extensor Muscle Strength in Middle-Aged and Older Individuals Undergoing Arthroscopic Partial Meniscectomy: A Systematic Review and Meta-Analysis

OBJECTIVE

People with meniscal tears are at high risk to develop or progress to knee osteoarthritis. Knee extensor weakness is considered a risk factor for osteoarthritis and is often reported in these individuals. The purpose of this systematic review and meta-analysis was to investigate knee extensor strength in people undergoing an arthroscopic partial meniscectomy (APM).

METHODS

Six databases (Medline, CINAHL, SPORTDiscus, Embase, PEDro, and AMED) were searched up to June 22, 2014. Studies that measured knee extensor muscle strength in people age ≥30 years undergoing APM for a meniscal tear and used either a healthy control group or the contralateral leg to compare knee extensor muscle strength were included. Methodological quality was assessed using guidelines from the Centre for Reviews and Dissemination.

RESULTS

Eleven studies, in which participants were predominantly male, were included (n = 596). A moderate reduction in muscle strength was observed prior to APM compared to controls (standardized mean difference [SMD] 0.58, 95% confidence interval [95% CI] 0.04, 1.13) and continued up to 6 months postsurgery (SMD range -2.42 to -0.47). There was no difference in muscle strength at 2 years post-APM (SMD -0.01 [95% CI -0.36, 0.35]), while a moderate reduction was again apparent at 4 years post-APM (SMD -0.56, [95% CI -1.20, 0.08]) compared to controls.

CONCLUSION

Our findings suggest that middle-aged and older individuals undergoing APM have reduced knee extensor muscle strength in the operated leg compared to control data. As meniscus pathology and knee extensor muscle weakness are risk factors for osteoarthritis, these results highlight the clinical importance of addressing muscle weakness in these individuals.

Reduced response of human meniscal cells to Osteogenic Protein 1 during osteoarthritis and pro-inflammatory stimulation

OBJECTIVE

Many cell types lose responsiveness to anabolic factors during inflammation and disease. Osteogenic Protein 1 (OP1/BMP7) was evaluated for the ability to enhance extracellular matrix synthesis in healthy and OA meniscus cells. Mechanisms of cell response to OP1 were explored.

DESIGN

Meniscus and cartilage tissues from healthy tissue donors and osteoarthritis (OA) patients undergoing total knee arthroplasties were acquired. Primary cell cultures were stimulated with OP1 and/or inflammatory factors (IL1α, IL1β, or fibronectin fragments (FnF)) and cellular responses were analyzed by RT-qPCR and immunoblots. Frozen section immunohistochemistry (IHC) was conducted to assess OP1 and receptor proteins in normal and OA meniscus.

RESULTS

OP1 treatment of normal meniscus cells resulted in significant, dose-dependent increases in ACAN (aggrecan) and COL2A1, and decreased MMP13 gene transcription, while only ACAN was upregulated (P < 0.01) at the highest dose of OP1 in OA meniscus cells. OP1 induced significantly more ACAN gene transcription in normal meniscus than normal articular cartilage (P = 0.05), and no differences between normal and OA cartilage were detected. Receptor expression and kinetics of canonical signaling activation were similar between normal and OA specimens. Normal meniscus cells treated with inflammatory factors were refractory to OP1 stimulation. Smad1 phosphorylation at an inhibitory site was induced (P = 0.01 for both normal and OA meniscus) by inflammatory cytokine treatment.

CONCLUSIONS

The meniscus demonstrates resistance to OP1 stimulation in OA and in the presence of inflammatory mediators. MAPK-mediated Smad1 linker phosphorylation is a possible mediator of the loss of anabolic extracellular matrix production in the inflammatory cytokine affected meniscus.