Gait analysis of walking before and after medial opening wedge high tibial osteotomy

Introduction

Medial opening wedge high tibial osteotomy (HTO) is used to treat medial compartment osteoarthritis (OA) of the knee. HTO shifts the weight-bearing line from the medial compartment into the lateral compartment. The aim of this study was to investigate the functional biomechanical consequences of this alteration in alignment.

Methods

Eleven male patients with medial compartment osteoarthritis underwent three-dimensional gait analysis during level walking before 12 months and after medial opening wedge HTO. Nine male control subjects of a similar age were also tested using the same protocol. Sagittal and coronal angles and moments in both operated and non-operated knees were compared. Pre and postoperative radiographic coronal plane alignment was also measured.

Results

Walking speed increased significantly postoperatively (P = 0.0001) and was not different from controls. Preoperatively, maximum knee flexion in stance was reduced compared to control (P = 0.02). Postoperatively, maximum knee flexion increased significantly (P = 0.005) and was the same as the controls. Similar changes were observed for the maximum knee flexion moment. The mean maximum varus angle during stance was reduced from 13.5° preoperatively to 5.4° postoperatively (P = 0.0001) compared to (6.8°) in controls. The mean maximum adduction moment also reduced from 3.9 to 2.7 (% Bw/ht, P = 0.02), compared to 3.6 in control subjects. Interestingly, the adduction moments in the non-operated knee increased postoperatively from 3.3 to 4.1 (% Bw/ht, P = 0.02). The mean radiological mechanical alignment was changed from 172 degrees preoperatively to 180 degrees postoperatively (P < 0.001).

Conclusion

HTO resulted in normalisation of several dynamic knee function parameters such as walking speed, knee flexion and external knee flexion moment. As anticipated, HTO reduced the varus angle and adduction moments of the operated knee. An increased adduction moment in the non-operated knee over the first postoperative year was found.

Level of evidence

Prospective case–control clinical laboratory study, Level III.     

Asymmetry of the knee extension deficit in standing affects weight-bearing distribution in patients with bilateral end-stage knee osteoarthritis

Purpose

The aim of this study was to evaluate weight-bearing distribution in patients with bilateral end-stage knee osteoarthritis (OA) and to clarify the gait parameters affecting the weight-bearing distribution during both standing and walking using gait analysis.

Methods

Twenty-five patients (averaged 71 years) with symptomatic bilateral end-stage medial knee OA participated in this study. They performed relaxed standing, placing one foot on a force plate and thereafter, level walking. First, knee resultant force was calculated on bilateral knees during standing. The knees in each patient were divided into Higher and Lower force side for the definition of dominant side limb. Second, gait parameters in each subject were compared between both sides.

Results

Each patient had large weight-bearing asymmetry, though passive range of motion, subjective pain level, femorotibial angle and radiographic disease severities were not significantly different between both sides. In standing, knees on Higher force side were significantly extended (11.2 ± 6.5°) than on Lower force side (14.4 ± 7.3°, P = 0.0086). Similarly, knees on Higher force side were also significantly extended at heel strike during gait. Besides, peak values of extension moment, knee adduction moment, knee adduction moment impulse and vertical force during gait were significantly greater on Higher force side.

Conclusions

Ability to extend the knee in standing was considered to be an essential factor to decide loading condition. It is clinically important to examine the ability to extend the knee in standing when considering loading asymmetry during gait in patients with bilateral knee OA.

Level of evidence

III.     

Changes in the loading of tibial articular cartilage following medial meniscectomy: a finite element analysis study

Purpose

Depending on the location and extent of the meniscectomy, loading on the tibial articular cartilage alters. The main purpose of the present study was to analyze the loading on the tibial articular cartilage following medial meniscectomy performed in various location and extent, as well as in the healthy knee, via finite element analyses on the solid models.

Methods

Totally, 11 finite element solid models, including the reference model, were created to investigate the effect of location (anterior, posterior, longitudinal) and extent of meniscectomy (25, 50, 75, and 100 %) on loading of tibial articular cartilage.

Results

Maximum equivalent stress of the tibial cartilage was measured 0.86 Megapascal in the reference model and increased approximately by 78 % in 25 % meniscectomy group, 177.9 % in 50 %, 473.8 % in 75 % meniscectomy group, and 752.6 % in total meniscectomy. When only the amount of meniscal tissue removed was considered ignoring the location of meniscectomy, no significant difference was found in the amount of tissue excised between 25 % meniscectomy and 50 % meniscectomy, as well as between 75 % meniscectomy and total meniscectomy.

Conclusion

In all meniscectomy models, the loadings on tibial articular cartilage increased. Except total meniscectomy, the highest impact was observed in longitudinal 75 % meniscectomy. During the surgical treatment, the contributions of menisci on load absorption by increasing the tibiofemoral contact area must be considered. In fact, the increase in the rate of loading on tibial articular cartilage depends on according to type and amount of meniscectomy.     

Is valgus unloader bracing effective in normally aligned individuals: implications for post-surgical protocols following cartilage restoration procedures

Purpose

Utilizing valgus unloader braces to reduce medial compartment loading in patients undergoing cartilage restoration procedures may be an alternative to non-weightbearing post-operative protocols in these patients. It was hypothesized that valgus unloader braces will reduce knee adduction moment during the stance phase in healthy subjects with normal knee alignment.

Methods

Gait analysis was performed on twelve adult subjects with normal knee alignment and no history of knee pathology. Subjects were fitted with an off-the-shelf adjustable valgus unloader brace and tested under five conditions: one with no brace and four with increasing valgus force applied by the brace. Frontal and sagittal plane knee angles and external moments were calculated during stance via inverse dynamics. Analyses of variance were used to assess the effect of the brace conditions on frontal and sagittal plane joint angles and moments.

Results

With increasing tension in the brace, peak frontal plane knee angle during stance shifted from 1.6° ± 4.2° varus without the brace to 4.1° ± 3.6° valgus with maximum brace tension (P = 0.02 compared with the no brace condition). Peak knee adduction moment and knee adduction impulse decreased with increasing brace tension (main effect of brace, P < 0.001). Gait velocity and sagittal plane knee biomechanics were minimally affected.

Conclusion

The use of these braces following a cartilage restoration procedure may provide adequate protection of the repair site without limiting the patient’s mobility.

Level of evidence

Therapeutic prospective comparative study, Level II.     

Correlation of WOMAC and KOOS scores to tibiofemoral cartilage loss on plain radiography and 3 Tesla MRI: data from the osteoarthritis initiative

Purpose

The purpose of this study was to determine the correlation between the Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) and Knee Injury Osteoarthritis Outcomes scores (KOOS) and the degree of tibiofemoral cartilage loss on plain radiography and 3T magnetic resonance imaging (MRI). We hypothesize that these subjective outcome scores will have a significant correlation to quantitative joint space loss.

Methods

Data used in the preparation of this article were obtained from the osteoarthritis initiative (OAI) database (OAI public use data sets kMRI_QCart_Eckstein18 and kXR_QJSW_Duryea16). Four hundred and forty-five patients had WOMAC/KOOS scores, quantitative tibiofemoral joints space width on plain radiographs and quantitative tibiofemoral cartilage thickness and per cent full thickness cartilage loss on 3T MRI. Joint space width on plain radiographs was correlated to cartilage thickness on MRI, and WOMAC/KOOS scores were correlated to the degree of cartilage loss using Pearson correlation coefficients.

Results

There was a statistically significant correlation between medial and lateral compartment cartilage thickness on MRI and medial and lateral joint space width on plain radiography (r = 0.86, r = 0.80) (p < 0.001). KOOS knee pain score was significantly correlated to increasing per cent full thickness cartilage loss in the medial femoral compartment (r = 0.34) (p < 0.001). KOOS symptom score was significantly correlated to decreasing joint space width in the medial (r = 0.16) and lateral (r = 0.15) compartment and increasing per cent full thickness cartilage loss in the medial femoral compartment (r = 0.36) (p < 0.001). No WOMAC score was correlated to degree of joint space width, cartilage thickness or per cent full thickness cartilage loss (n.s).

Conclusion

The WOMAC and KOOS scores are poor indicators of tibiofemoral cartilage loss, with only the KOOS symptom and knee pain score being weakly correlated. Osteoarthritis is a multifactorial process and the need to treat patients based off their symptoms and rely on radiographs as confirmatory modalities, and not diagnostic modalities, when talking about OA and medical intervention.

Level of evidence

Level 2.     

Meniscectomy leads to early changes in the mineralization distribution of subchondral bone plate

Purpose

It is generally recognized that the subchondral bone plate (SBP) is involved in development of osteoarthritis (OA). However, the pathophysiological significance is not yet clear. The goal of this study is to investigate the extent of the changes that occur in SBP of the tibial plateau in the early stages of experimental OA.

Methods

Forty-three female rabbits were assigned to 5 experimental (n = 8 each group) and one sham group (n = 3). OA was induced by medial meniscectomy in the right knee, the left knee served as control. 2, 4, 8, 12, and 24 weeks after meniscectomy, cartilage damage was evaluated, and bone mineral density (BMD) and mineralization distribution of the SBP was measured by computed tomography osteoabsorptiometry (CT-OAM).

Results

Cartilage damage started 2 weeks after meniscectomy with surface roughening. Cartilage defects increased over time. 24 weeks postoperatively, subchondral bone was exposed. As early as 2 weeks after meniscectomy, BMD in the medial tibial plateau decreased significantly. BMD increased again and reached the values of the non-operated knee 12 weeks postoperatively. In addition, already 4 weeks after meniscectomy a significant shift of the densitiy maximum on the medial tibial plateau, which is normally centrally located toward the margin was observed.

Conclusions

In conclusion, the results of this study contribute to the concept of early involvement of the SBP in the development of OA. The hypothesis that changes in the SBP occur simultaneously to cartilage damage was confirmed.     

Partial lateral facetectomy plus Insall’s procedure for the treatment of isolated patellofemoral osteoarthritis: survival analysis

Purpose

The purpose of this study was to report the survival analysis of partial lateral facetectomy and Insall’s procedure in patients with isolated patellofemoral osteoarthritis, and to assess the risk and protective factors for failure of this procedure.

Methods

From 1992 to 2004, all subjects with isolated patellofemoral osteoarthritis who met the inclusion criteria and underwent this procedure were enrolled. Risk and protective factors for failure (failure considered as the need for total knee arthroplasty) were assessed by comparing obtained baseline data between failed and non-failed cases. Eighty-seven cases (mean (SD) age 61.8 (7.7) years, mean (SD) follow-up 9.6 (3.2) years) were included.

Results

Twenty-three failed cases were found. Mean (SD) survival time was 13.6 (0.5) years. At 13 years (last failure case), the cumulative survival was 59.3 %. Baseline medial tibiofemoral pain, genu flexum, and worst grade of tibiofemoral osteoarthritis were significant risk factors for failure (p < 0.0001, p = 0.02, p < 0.0001, respectively). In contrast, higher anatomical (p = 0.02) and total (p = 0.03) knee society score (KSS) scores, absence of knee effusion (p = 0.03), higher value of the Caton–Deschamps index (p = 0.03), and lateral position of the patella (p = 0.01) were all protective factors against failure.

Conclusion

The treatment for isolated patellofemoral osteoarthritis through partial lateral facetectomy and Insall’s procedure demonstrated good long-term survival. The presence of preoperative medial tibiofemoral pain, genu flexum, and incipient tibiofemoral osteoarthritis increased the risk of failure of this procedure. In contrast, higher anatomical and total KSS scores, absence of knee effusion, higher value of the Caton–Deschamps index, and lateral position of the patella were found to protect against failure.

Level of evidence

Prospective case series, Level IV.     

Courses of change in knee adduction moment and lateral thrust differ up to 1 year after TKA

Purpose

In total knee arthroplasty (TKA), dynamic knee loading may loosen the artificial joint and bone or cause polyethylene wear after prolonged use. TKA decreases knee adduction moment at 6 months, but this effect is lost by 1 year post-operatively. However, lateral thrust after TKA has not been clarified. We hypothesized that like knee adduction moment, lateral thrust would return to baseline levels by 1 year post-operatively.

Methods

Participants were 15 patients who underwent TKA for medial knee OA. Japanese Orthopaedic Association (JOA) score, numeric rating scale, and gait analysis (measurement of peak knee adduction moment, knee varus angle at peak knee adduction moment, lateral thrust, and gait speed) were performed preoperatively (baseline) and 3 weeks, 3 and 6 months, and 1 year post-operatively.

Results

JOA score improved from 55 ± 9.8 to 78 ± 12.1 at 1 year post-operatively, and pain decreased significantly from baseline at each follow-up (p < 0.001). Significant increases in gait speed were observed at 6 months and 1 year (p < 0.001). Peak knee adduction moment during stance phase was significantly lower at 3 weeks, 3 months, and 6 months compared to baseline (p < 0.05), but no significant changes were seen at 1 year. Knee varus at peak knee adduction moment did not differ significantly between any measurement points, while lateral thrust was decreased at 6 months and 1 year compared to baseline (p < 0.05).

Conclusions

Temporal courses of changes up to 1 year after TKA differed between knee adduction moment and lateral thrust, so our hypothesis was rejected.

Level of evidence

IV.

     

Changes in articular cartilage following arthroscopic partial medial meniscectomy

Purpose

To examine degenerative changes in all cartilage surfaces of the knee following arthroscopic partial medial meniscectomy.

Methods

For this prospective cohort study, 14 patients (five female) with a mean age of 47.9 ± 12.9 years who had undergone isolated arthroscopic partial medial meniscectomy were evaluated. Cartilage-sensitive magnetic resonance imaging (MRI) scans were acquired from the operated knees before the index operations, as well as at 6, 12, and 24 months after surgery. The MRI scans were assessed for the prevalence, severity, and size of cartilage degenerations. The clinical outcome was assessed using the SF-36 physical and mental component score and the International Knee Documentation Committee Knee Evaluation Form and was correlated with radiological findings.

Results

There was a significant increase in the severity of cartilage lesions in the medial tibial plateau (P = 0.019), as well as a trend towards an increase in the lateral tibial plateau. The size of the cartilage lesions increased significantly in the medial femoral condyle (P = 0.005) and lateral femoral condyle (P = 0.029), as well as in the patella (P = 0.019). Functional outcome scores improved significantly throughout the follow-up period. There was no correlation between cartilage wear and functional outcome.

Conclusions

Arthroscopic partial medial meniscectomy is associated with adverse effects on articular cartilage and may lead to an increase in the severity and size of cartilage lesions. Post-operative cartilage wear predominantly affected the medial compartment and also affected the other compartments of the knee. Strategies to reduce subsequent osteoarthritic changes need to involve all compartments of the knee.

Level of evidence

IV.

     

Association between varus alignment and post-traumatic osteoarthritis after anterior cruciate ligament injury

Purpose

To investigate the association between varus alignment and post-traumatic osteoarthritis (OA) after an anterior cruciate ligament (ACL) injury.

Methods

One hundred subjects with an acute complete ACL tear were followed for 15 years. Anterior–posterior radiographs of the tibiofemoral joint were obtained with a knee flexion of 20°, and the patellofemoral joint was examined with skyline view at 50° knee flexion. Joint space narrowing and osteophytes were graded in the tibiofemoral and patellofemoral joints in the injured (ACL) and uninjured knee according to the radiographic atlas of the Osteoarthritis Research Society International. The alignment of the uninjured, contralateral knee was measured at follow-up, using full-limb radiographs of leg with the knee in full extension. Alignment was expressed as the hip-knee-ankle (HKA) angle. Alignment was defined as valgus (HKA ≤178°), neutral (179°–181°) or varus (≥182°).

Results

Data from 68 subjects were included in the analysis. Varus alignment of the uninjured knee at follow-up appeared to be associated with OA of the injured knee 15 years after an ACL injury (odds ratio (95 % confidence interval) 3.9 (1.0–15.8, p = 0.052)).

Conclusions

Varus alignment of the uninjured knee at follow-up may be associated with OA of the injured knee 15 years after an ACL injury.

Level of evidence

II.     

Ultrasonographic evaluation of the femoral cartilage thickness after unilateral arthroscopic partial meniscectomy

Purpose

To assess the distal femoral cartilage after unilateral arthroscopic partial meniscectomy and to explore the relationship between cartilage thickness and various disease-/surgery-related parameters.

Methods

Eighty-nine patients (42 M, 47 F) who had undergone arthroscopic partial meniscectomy surgery were evaluated. Ultrasonographic distal femoral cartilage thicknesses were measured with a 5–13-MHz linear probe (General Electric, Logiq P5) on mid-points of the lateral condyle, intercondylar notch and medial condyle of operated and non-operated knees by a physician blinded to patients’ data. Demographic features, duration after surgery, type of meniscal tear and site of meniscectomy were recorded.

Results

Mean age of the patients was 51.8 ± 12.8 years (range 18–88). Mean body mass index was 29.4 ± 4.4 kg/m² (range 18–38). Overall, in patients with degenerative meniscal tears, femoral cartilage thicknesses pertaining to all the three measured sites (lateral, intercondylar and medial) were found to be decreased in the operated knees when compared with those of the non-operated knees (p = 0.004, p = 0.003, p = 0.041, respectively), whereas in patients with non-degenerative tears, this decrease was significant only in the intercondylar area (p = 0.038). When patients were grouped according to the duration (months) after their surgery (≤36, 37–48 and ≥49), cartilage thickness was similar between both knees in the first group, decreased at the lateral condyle (p = 0.008) and intercondylar area (p = 0.049) in the second group and decreased at all three sites (lateral, intercondylar and medial) in the third group (p = 0.015, p = 0.005 and p = 0.008, respectively).

Conclusion

These findings would be considered as unfavourable with respect to weight-bearing, and thus, conservative measures to support relevant joints would strongly be kept in mind during clinical practice. Lastly, ultrasonography may be a convenient alternative imaging method for the evaluation of short- and medium-term cartilage loss in patients with arthroscopic partial meniscectomy.

Levels of evidence

III.     

Effects of the use of oral contraceptives on hip and knee kinematics in healthy women during anterior stair descent

Purpose

Our aim was to evaluate the effects of the use of oral contraceptives (OC) on the hip and knee kinematics of healthy women during anterior stair descent.

Methods

Forty volunteers aged from 18 to 26 years were divided into two groups: 1—Group of women who had used OC for at least 3 months prior to evaluation (n = 20) and 2—Group of women who did not use OC (n = 20). The knee flexion/extension and abduction/adduction, hip flexion/extension, abduction/adduction and medial/lateral rotation excursions (degrees) were calculated for the dominant (supporting) limb during anterior stair descent. T tests for independent samples were used to compare the kinematic differences between the groups (α = 0.05).

Results

No significant difference was verified between the groups regarding the maximum excursion of knee flexion (n.s.) and abduction (n.s.) or hip flexion (n.s.), adduction (n.s.) and medial rotation (n.s.). When considering the knee flexion at 50°, no significant difference was verified between the groups regarding the excursion of knee abduction (n.s.) or hip flexion (n.s.) adduction (n.s.) and medial/lateral rotation (n.s.).

Conclusion

These results suggest that the use of OC does not influence the hip and knee kinematics during anterior stair descent. Therefore, the role of this medication as a protective factor against anterior cruciate ligament injuries remains questionable.

Level of evidence

III.     

Staged medial opening wedge high tibial osteotomy for bilateral varus gonarthrosis: biomechanical and clinical outcomes

Purpose

(1) To evaluate the effect of staged bilateral medial opening wedge high tibial osteotomy (HTO) on established biomechanical risk factors for disease progression and on validated measures of pain and function and (2) To compare outcomes in patients having the second surgery staged within or beyond 12 months of the first surgery.

Methods

Thirty-seven patients with bilateral varus alignment and medial compartment osteoarthritis underwent staged bilateral medial opening wedge HTO (21 within and 16 beyond 12 months). Patients underwent full-limb standing anteroposterior radiographs to determine frontal plane alignment (mechanical axis angle) and three-dimensional gait analysis to estimate the distribution of load across the tibiofemoral compartments (external knee adduction moment). Patients also completed the Knee Injury and Osteoarthritis Outcomes Scores (KOOS), the Lower Extremity Functional Scale, the Short Form Health Survey and the six-minute walk test (6MWT). Patients (both limbs) were evaluated before and approximately 6, 12 and 24 months after each surgery.

Results

There were statistically and clinically significant changes in both limbs that were of similar magnitudes and that remained relatively stable over time postoperatively. Mean (95 % CI) improvements in outcomes were as follows. Mechanical axis angle: 9.4° (8.4°, 10.4°) (i.e. average change of both limbs), peak knee adduction moment: ?1.7 %BW*Ht (?2.1, ?1.4 %BW*Ht) (i.e. average change of both limbs), 6MWT: 36.7 m (19.4, 54.0 m), SF-12 Physical Component Summary: 12.0 (8.5, 15.5) and KOOS Pain: 25.4 (19.6, 31.2). Other than the shorter time period to reach maximum benefit of both surgeries, there were no remarkable differences at final assessment between patients having surgeries staged within or beyond 12 months.

Conclusions

The present findings demonstrate that patients with bilateral varus gonarthrosis experience marked improvements in established biomechanical risk factors for disease progression bilaterally (mechanical axis angles and external knee adduction moments), as well as clinically important improvements in patient-important outcomes, after staged medial opening wedge HTO. Current findings suggest no difference in outcomes for patients who have the second surgery staged within or beyond 12 months of the first surgery.

Level of evidence

IV.     

Increased medial foot loading during drop jump in subjects with patellofemoral pain

Purpose

To compare medial-to-lateral plantar forces during drop jump and single leg squat in individuals with and without patellofemoral pain.

Methods

This cross-sectional study compared 23 young adults with patellofemoral pain to 20 age- and sex-matched controls without knee pain. The plantar pressure distribution was collected during drop jump and single leg squat using pressure-sensitive Pedar insoles, inserted into a standard flat shoe. The primary outcome was the medial-to-lateral force, quantified as the peak force under the medial forefoot as the percentage of force under the total forefoot during drop jump. Secondary outcomes included peak medial-to-lateral force during single leg squat and mean forces during drop jump and single leg squat.

Results

The primary outcome showed that individuals with patellofemoral pain had a 22 % higher medial-to-lateral peak force during drop jump, (p = 0.03). Secondary outcomes showed 32 % higher medial-to-lateral peak force during single leg squat (p = 0.01) and 19–23 % higher medial-to-lateral mean force during drop jump and single leg squat (p = 0.02–0.04).

Conclusion

These findings indicate that individuals with patellofemoral pain display a more medially oriented loading pattern of the forefoot compared to individuals without knee pain. This loading pattern may be associated with the distribution of forces acting on the patellofemoral joint and suggest treatment of PFP should consider interventions that target normalisation of foot loading.

Level of evidence

III.     

Osteoarthritis of the patella, lateral femoral condyle and posterior medial femoral condyle correlate with range of motion

Purpose

The type of osteoarthritis and the degree of severity which causes restriction of knee range of motion (ROM) is still largely unknown. The objective of this study was to analyse the location and the degree of cartilage degeneration that affect knee range of motion and the connection, if any, between femorotibial angle (FTA) and knee ROM restriction.

Methods

Four hundreds and fifty-six knees in 230 subjects with knee osteoarthritis undergoing knee arthroplasty were included. Articular surface was divided into eight sections, and cartilage degeneration was evaluated macroscopically during the operation. Cartilage degeneration was classified into four grades based on the degree of exposure of subchondral bone. A Pearson correlation was conducted between FTA and knee flexion angle to determine whether high a degree of FTA caused knee flexion restriction. A logistic regression analysis was also conducted to detect the locations and levels of cartilage degeneration causing knee flexion restriction.

Results

No correlation was found between FTA and flexion angle (r = ?0.08). Flexion angle was not restricted with increasing FTA. Logistic regression analysis showed significant correlation between restricted knee ROM and levels of knee cartilage degeneration in the patella (odds ratio (OR) = 1.77; P = 0.01), the lateral femoral condyle (OR = 1.62; P = 0.03) and the posterior medial femoral condyle (OR = 1.80; P = 0.03).

Conclusion

For clinical relevance, soft tissue release and osteophyte resection around the patella, lateral femoral condyle and posterior medial femoral condyle might be indicated to obtain a higher degree of knee flexion angle.

Level of evidence

Case–control study, Level III.     

Patellofemoral arthroplasty: outcomes and factors associated with early progression of tibiofemoral arthritis

Purpose

The purpose of this study was to review the results of patellofemoral arthroplasty (PFA) performed by a single surgeon at a single institution in order to determine factors associated with clinical outcomes and progression of tibiofemoral degenerative joint disease.

Methods

Sixty-one patients with isolated patellofemoral osteoarthritis were treated with a PFA by a single surgeon between 2003 and 2009. Fifty-nine patients were available for analysis with a mean follow-up of 4 years (range 2–6 years). Patients were evaluated by measuring range of motion and with the use of the Knee Society clinical rating system, the Tegner Activity Level Scale, and the UCLA Activity Score. In addition, preoperative radiographs were evaluated for patellofemoral and tibiofemoral compartment osteoarthritis and presence of trochlear dysplasia, and post-operative radiographs were reviewed for progression of tibiofemoral degenerative arthritis. Furthermore, multivariate statistical methods were applied to study factors that had potential to influence the final outcome.

Results

There was no statistically significant association between age, gender, history of prior knee surgery, patellar height, patellofemoral osteoarthritis severity, patellar and femoral component size, or performance of lateral release with patient pain and function (as measured by the Knee Society scores) or progression of tibiofemoral joint osteoarthritis at final follow-up. Increased preoperative body mass index (BMI) was associated with lower post-operative Knee Society function scores (p = 0.03). Patients with preoperative trochlear dysplasia had significantly less radiographic evidence of tibiofemoral joint osteoarthritis progression compared with patients without trochlear dysplasia at final follow-up (p < 0.0001).

Conclusion

In this study, patients with preoperative radiographic evidence of trochlear dysplasia experienced less progression of tibiofemoral degenerative joint disease than patients without trochlear dysplasia at a mean follow-up of 4 years.

Level of evidence

IV.     

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Level of evidence

III.     

Patellofemoral arthroplasty influences tibiofemoral kinematics: the effect of patellar thickness

Purpose

Although controversy still remains, isolated patellofemoral arthroplasty recently gained in popularity as a treatment option for patellofemoral osteoarthritis. It has compared to total knee arthroplasty the advantage of preserving the tibiofemoral articulation, which in theory would allow the preservation of natural tibiofemoral kinematics. Today, however, no data exist to support this assumption. This study was therefore performed in order to investigate the effect of isolated patellofemoral arthroplasty on the native three-dimensional tibiofemoral kinematic behaviour and whether a change in patellar thickness would have an influence.

Methods

Six fresh-frozen cadavers were fixed on a custom-made mechanical knee rig. Full 3D kinematics was analysed during passive flexion–extension cycles, open chain extension, with and without mechanical resistance, as well as deep knee squats, using infrared motion capture cameras and retroflective markers. Measurements were taken for the native knee and after prosthetic trochlear resurfacing with and without patellar resurfacing in three different patellar thicknesses.

Results

Compared to the natural knee, patellofemoral arthroplasty resulted in significant changes in tibiofemoral kinematics, which were most pronounced in the most loaded motor tasks. Increased internal tibial rotation was noted in the mid- and high flexion ranges, reaching at 120° of flexion a mean difference of 4.5° ± 4.3° (p < 0.0001) during squat motion, over the whole flexion range during open chain motion and in deeper flexion beyond 50° (mean at 70°, 1.9° ± 3.7°) during resisted open chain. During squats, also, a more posterior translation of the lateral femoral condyle was observed. The effect was accentuated in case of patella overstuffing, whereas kinematics was closer to normal with patellar thinning.

Conclusion

Isolated patellofemoral arthroplasty alters natural tibiofemoral kinematics, and the effects become more pronounced in case of increased patellar thickness. Therefore, it might be recommended to aim for a slight over-resection of patellar bone if sufficient bone stock is available.     

Does varus alignment increase after medial meniscectomy?

Purpose

In patients who underwent arthroscopic meniscectomy for medial meniscus tears, the authors wished to ascertain (1) whether varus alignment in the lower extremity would increase after an operation and (2) if so, what the related factors would be.

Methods

Among 181 patients from 20 to 60 years of age who underwent arthroscopic medial meniscectomy for medial meniscus tears between 2002 and 2005, 56 patients followed for a minimum period of 5 years were enroled for this study. Alignment in the lower extremity was measured preoperatively and again at the last follow-up. Change in varus alignment (the difference between preoperative alignment and alignment at the last follow-up) was analyzed in relation to sex, age, body mass index (BMI), resection amount (partial vs. total), preoperative alignment, and follow-up duration, using multiple linear regression analysis.

Results

Varus deformity increased by 1.7° ± 1.5° from a preoperative mean of 2.4° ± 2.4° to a mean of 4.1° ± 3.0° at the last follow-up, which was statistically significant (p = 0.000). From multiple linear regression analysis, only the resection amount (partial meniscectomy or total meniscectomy) was found to be significantly related to the change in varus alignment (p = 0.002). Other factors including sex, age, BMI, preoperative alignment, presence of cartilage injury and follow-up duration were not significantly related to the change in varus alignment after the operation.

Conclusions

Arthroscopic meniscectomy performed in patients with medial meniscus tears aggravated varus alignment in the lower extremity at the last follow-up. In addition, the increase in varus deformity was significantly higher among patients with total meniscectomy than among those with partial meniscectomy.

Level of evidence

Retrospective comparative study, Level III.     

Increased cartilage volume after injection of hyaluronic acid in osteoarthritis knee patients who underwent high tibial osteotomy

Purpose

High tibial osteotomy (HTO) is a surgical procedure used to correct abnormal mechanical loading of the knee joint; additionally, intra-articular hyaluronic acid injections have been shown to restore the viscoelastic properties of synovial fluid and balance abnormal biochemical processes. It was hypothesized that combining HTO with intra-articular hyaluronic acid injections would have benefit to improve the cartilage volume of knee joints.

Methods

Forty patients with medial compartment knee osteoarthritis (OA) were randomly placed into 1 of 2 groups. The study group (n = 20) received 2 cycles (at 6-month intervals) of 5 weekly intra-articular hyaluronic acid injections after HTO operation. The control group (n = 20) did not receive any intra-articular injections after HTO surgery. Cartilage volume (primary outcome) was assessed by magnetic resonance imaging (MRI) pre-operatively and 1 year post-operatively. Treatment efficacy (secondary outcomes) was evaluated with the Western Ontario and McMaster Universities OA Index (WOMAC) and by the comparison of the total rescue medication (paracetamol/diclofenac) used (weeks 6, 12, 24, 48).

Results

MRI studies showed a significant increase in total cartilage volume (p = 0.033), lateral femoral cartilage volume (p = 0.044) and lateral tibial cartilage volume (p = 0.027) in the study group. Cartilage volume loss was detected at the lateral tibial plateau in the control group. There were significant improvements after surgery in both groups for all subscales of WOMAC scores (p < 0.001) compared to the baseline. However, no difference was found between the two groups. The study group had significantly lower amounts of diclofenac consumption (p = 0.017).

Conclusion

Based on the findings of the present study, intra-articular hyaluronic acid injections may be beneficial for increasing total cartilage volume and preventing the loss of lateral tibiofemoral joint cartilage after HTO.

Level of evidence

Therapeutic study, Level I.