Background
Most knee surgeons have believed during TKA neutral mechanical alignment should be restored. A number of patients may exist, however, for whom neutral mechanical alignment is abnormal. ...Patients with so-called “constitutional varus” knees have had varus alignment since they reached skeletal maturity. Restoring neutral alignment in these cases may in fact be abnormal and undesirable and would likely require some degree of medial soft tissue release to achieve neutral alignment.
Questions/purposes
We investigated what percentage of the normal population has constitutional varus knees and what are the contributing factors.
Subjects and Methods
We recruited a cohort of 250 asymptomatic adult volunteers between 20 and 27 years old for this cross-sectional study. All volunteers had full-leg standing digital radiographs on which 19 alignment parameters were analyzed. The incidence of constitutional varus alignment was determined and contributing factors were analyzed using multivariate prediction models.
Results
Thirty-two percent of men and 17% of women had constitutional varus knees with a natural mechanical alignment of 3° varus or more. Constitutional varus was associated with increased sports activity during growth, increased femoral varus bowing, an increased varus femoral neck-shaft angle, and an increased femoral anatomic mechanical angle.
Conclusions
An important fraction of the normal population has a natural alignment at the end of growth of 3° varus or more. This might be a consequence of Hueter-Volkmann’s law. Restoration of mechanical alignment to neutral in these cases may not be desirable and would be unnatural for them.
Level of Evidence
Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
The lateral closing and medial opening wedge high tibial osteotomy can correct a varus malalignment of the knee caused by medial compartment osteoarthritis. These procedures have produced great ...short-term and mid-term results. As no systematic review has examined their long-term results yet, the goal of this article was to compare the results of all articles about lateral closing and medial opening wedge high tibial osteotomies, published after the year 2000, with a mean follow-up of more than 10 years. A systematic search of the Medline, Web of Science and Cochrane databases resulted in the inclusion of 30 articles. All these studies combined examined the results of 7087 high tibial osteotomies in a total of 6636 patients after a mean follow-up of more than 10 years. Primary outcome measures were the survival rate of the osteotomy, functional scores, patient satisfaction and pain scores. Secondary outcome measures were alignment correction and the identification of factors influencing the survival of the osteotomy. The 5-year, 10-year, 15-year and 20-year survival rates, respectively, ranged from 86 to 100%, 64–97.6%, 44–93.2% and 46–85.1%. The subjective scoring systems showed an improvement postoperatively that was maintained until final follow-up. The anatomical and mechanical tibiofemoral axis were, respectively, corrected to a mean of 7.3°–13.8° of valgus and 0.6°–4° of valgus. The results of the articles evaluating the influence of potential risk factors were contradictory. Despite the low quality of the available evidence, the lateral closing and medial opening wedge high tibial osteotomy seem to remain valid long-term treatment options for patients with painful varus malalignment caused by isolated medial compartment osteoarthritis of the knee. The available results indicate that the need for arthroplasty could be delayed for more than 15 years in the majority of patients. However, higher-quality studies are needed to confirm these findings. As a systematic review is assigned a level of evidence equivalent to the lowest level of evidence used from the analyzed manuscripts, the level of evidence of this systematic review is IV.
There is an ongoing debate whether gender differences in the dimensions of the knee should influence the design of TKA components. We hypothesized that not only gender but also the patient’s ...morphotype determined the shape of the distal femur and proximal tibia and that this factor should be taken into account when designing gender-specific TKA implants. We reviewed all 1000 European white patients undergoing TKA between April 2003 and June 2007 and stratified each into one of three groups based on their anatomic constitution: endomorph, ectomorph, or mesomorph. Of the 250 smallest knees, 98% were female, whereas 81% of the 250 largest knees were male. In the group with intermediate-sized knees, female knees were narrower than male knees. Patients with smaller knees (predominantly female) demonstrated large variability between narrow and wide mediolateral dimensions irrespective of gender. The same was true for larger knees (predominantly male). This variability within gender could partially be explained by morphotypic variation. Patients with short and wide morphotype (endomorph) had, irrespective of gender, wider knees, whereas patients with long and narrow morphotype (ectomorph) had narrower knees. The shape of the knee is therefore not only dependent on gender, but also on the morphotype of the patient.
Level of Evidence:
Level I, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
Current ultrasound techniques face several challenges to measure strains when translated from large tendon to in-situ knee collateral ligament applications, despite the potential to reduce knee ...arthroplasty failures attributed to ligament imbalance. Therefore, we developed, optimized and validated an ultrasound speckle tracking method to assess the in-situ strains of the medial and lateral collateral ligaments. Nine cadaveric legs with total knee implants were submitted to varus/valgus loading and divided into two groups: "optimization" and "validation". Reference strains were measured using digital image correlation technique, while ultrasound data were processed with a custom-built speckle tracking approach. Using specimens from the "optimization" group, several tracking parameters were tuned towards an optimized tracking performance. The parameters were ranked according to three comparative measures between the ultrasound-based and reference strains: R
, mean absolute error and strains differences at 40 N. Specimens from the "validation" group, processed with the optimal parameters, showed good correlations, along with small mean absolute differences, with correlation values above 0.99 and 0.89 and differences below 0.57% and 0.27% for the lateral and medial collateral ligaments, respectively. This study showed that ultrasound speckle tracking could assess knee collateral ligaments strains in situ and has the potential to be translated to clinics for knee arthroplasty-related procedures.
Background: As the natural healing capacity of damaged articular cartilage is poor, joint surface injuries are a prime target for regenerative
medicine. Characterized chondrocyte implantation uses an ...autologous cartilage cell therapy product that has been optimized
for its biological potency to form stable cartilage tissue in vivo.
Purpose: To determine whether, in symptomatic cartilage defects of the femoral condyle, structural regeneration with characterized
chondrocyte implantation is superior to repair with microfracture.
Study Design: Randomized controlled trial; Level of evidence, 1.
Methods: Characterized chondrocyte implantation was compared with microfracture in patients with single grade III to IV symptomatic
cartilage defects of the femoral condyles in a multicenter trial. Patients aged 18 to 50 years were randomized to characterized
chondrocyte implantation (n = 57) or microfracture (n = 61). Structural repair was blindly assessed in biopsy specimens taken
at 1 year using (1) computerized histomorphometry and (2) evaluation of overall histological components of structural repair.
Clinical outcome was measured using the self administered Knee injury and Osteoarthritis Outcome Score. Adverse events were
recorded throughout the study.
Results: Characterized chondrocyte implantation resulted in better structural repair, as assessed by histomorphometry ( P = .003) and overall histologic evaluation ( P = .012). Aspects of structural repair relating to chondrocyte phenotype and tissue structure were superior with characterized
chondrocyte implantation. Clinical outcome as measured by the Knee injury and Osteoarthritis Outcome Score at 12 to 18 months
after characterized chondrocyte implantation was comparable with microfracture at this stage. Both treatment groups had a
similar mean baseline overall Knee injury and Osteoarthritis Outcome Score (56.30 ± 13.61 and 59.53 ± 14.95 for microfracture
and characterized chondrocyte implantation, respectively), which increased in both groups to 70.56 ± 12.39 and 72.63 ± 15.55
at 6 months, 73.26 ± 14.66 and 73.10 ± 16.01 at 12 months, and 74.73 ± 17.01 and 75.04 ± 14.50 at 18 months, respectively.
Both techniques were generally well tolerated; the incidence of adverse events after characterized chondrocyte implantation
was not markedly increased compared with that for microfracture.
Conclusion: One year after treatment, characterized chondrocyte implantation was associated with a tissue regenerate that was superior
to that after microfracture. Short-term clinical outcome was similar for both treatments. The superior structural outcome
may result in improved long-term clinical benefit with characterized chondrocyte implantation. Long-term follow-up is needed
to confirm these findings.
Keywords:
chondrocyte
chondral
regenerative medicine
autologous chondrocyte implantation (ACI)
characterized chondrocyte implantation (CCI)
cell therapy product
microfracture
cartilage repair
Ligament balancing during total knee arthroplasty (TKA) often relies on subjective surgeon experience. Although instrumented tibial trays facilitate an objective assessment of intraoperative joint ...balance through quantification of intra-articular joint loads, postoperative clinical assessment of joint balance relies on passive stress tests quantifying varus–valgus joint laxity. This study aimed at correlating the intraoperative and postoperative metrics used to assess joint balance while also comparing joint loads obtained during passive assessment and active functional motions. Four experienced surgical fellows were assigned a fresh-frozen lower limb each to plan and perform posterior-stabilised TKA. An instrumented tibial insert measured intraoperative intra-articular loads. Specimens were then subjected to passive flexion–extension, open-chain extension, active squatting, and varus–valgus laxity tests on a validated knee simulator. Intra-articular loads were recorded using the instrumented insert and tibiofemoral kinematics using an optical motion capture system. A negative correlation was observed between mean intraoperative intra-articular loads and corresponding mean postoperative tibial abduction angle during laxity tests (medial: R = −0.93, p = 0.02; lateral: R = −0.88, p = 0.04); however, this was not observed for each specimen. Peak intra-articular load distribution for active squatting was lateral-heavy, contrasting to the medial-heavy distribution observed in passive intraoperative measurements, for all specimens. These aspects should be given due consideration while assessing intraoperative and postoperative joint stability following TKA.
A combination of conventional computed tomography and single photon emitted computed tomography (SPECT/CT) provides simultaneous data on the intensity and location of osteoblastic activity. ...Currently, since SPECT/CT scans are not spatially aligned, scans following knee arthroplasty are compared by extracting average and maximal values of osteoblastic activity intensity from large subregions of the structure of interest, which leads to a loss of resolution, and hence, information. Therefore, this paper describes the SPECT/CT registration platform (SCreg) based on the principle of image registration to spatially align SPECT/CT scans following unicondylar knee arthroplasty (UKA) and allow full resolution intra-subject and inter-subject comparisons.
SPECT-CT scans of 20 patients were acquired before and 1 year after UKA. Firstly, scans were pre-processed to account for differences in voxel sizes and divided in volumes of interest. This was followed by optimization of registration parameters according to their volumetric agreement, and alignment using a combination of rigid, affine and non-rigid registration. Finally, radiotracer uptakes were normalized, and differences between pre-operative and post-operative activity were computed for each voxel. Wilcoxon signed rank sum test was performed to compare Dice similarity coefficients pre- and post-registration.
Qualitative and quantitative validation of the platform assessing the correct alignment of SPECT/CT scans resulted in Dice similarity coefficient values over 80% and distances between predefined anatomical landmarks below the fixed threshold of (2;2;0) voxels. Locations of increased and decreased osteoblastic activity obtained during comparisons of osteoblastic activity before and after UKA were mainly consistent with literature.
Thus, a full resolution comparison performed on the platform could assist surgeons and engineers in optimizing surgical parameters in view of bone remodeling, thereby improving UKA survivorship.
Knee osteoarthritis is a common problem, but often underdiagnosed and undertreated in primary care as compared to evidence-based guidelines. Educational outreach visits are an effective strategy to ...improve guideline adherence, but its contribution to knee osteoarthritis management is largely unknown. The aim of this study was to evaluate the overall effectiveness of educational outreach visits on process quality indicators for knee osteoarthritis management, more specifically on the referral for physical therapy.
An educational intervention study, non-randomized and controlled, was designed for general practitioners (GPs) in Belgium. During four months, 426 GPs were visited by academic detailers and allocated to the intervention group. The control group was selected from GPs not visited by academic detailers during the study period. Six months post-intervention, both groups received a questionnaire with two case-vignettes to measure the effectiveness of the educational outreach. Outcomes were assessed with a Belgian set of quality indicators for knee osteoarthritis management and focused on the number of prescriptions for appropriate physical therapy (i.e. muscle strengthening, aerobic, functional or range of motion exercises) and the adherence to eight additional quality indicators related to knee osteoarthritis management. For the analysis, multivariable logistic regression models were used and Generalized Estimating Equations to handle the correlation between the multiple results per GP.
The intervention group showed a tendency to prescribe more frequently at least one appropriate physical therapy for a case (43.8%), compared to the control group (31.3%, p = 0.057). Muscle strengthening exercises were the most frequently prescribed therapy with 37.0% in the intervention versus 26.9% in the control group. The adherence to the other quality indicators showed no significant difference between the intervention and control group and varied between 8.9 and 100% in the intervention group.
This intervention did not alter significantly the adherence to quality indicators and in particular the probability of prescribing physical therapy. To change general practitioners' prescription behavior, more extensive or combined interventional approaches seem warranted.
Abstract Standard gait analysis reports knee joint rotations in the three anatomical planes without addressing their different levels of reliability. Most clinical studies also restrict analysis to ...knee flexion–extension, because knee abduction–adduction and axial rotation are small with respect to the corresponding amount of measurement artefact. This study analyses a set of 11 motor tasks, in order to identify those that are adequately repeatable and that can induce greater motion at the knee than walking. Ten volunteers (mean ± SD age: 29 ± 9 years) each underwent three motion analysis sessions on different days with a standard gait analysis system and protocol. In each session they performed normal walking, walking with sidestep and crossover turns, ascent onto and descent off a step, descent with sidestep and crossover turns, chair rise, mild and deep squats, and lunge. Range and repeatability of motions in the three anatomical planes were compared by ANOVA. The sidestep turns showed a range of axial rotation significantly larger than that in walking (about 8°), while maintaining similar levels of repeatability. Ascent, chair rise, squat, and lunge showed greater flexion ranges than walking; among these, ascent was the most repeatable. The results show that turning increases knee axial rotation in young subjects significantly. Further, squats and lunges, currently of large interest in orthopaedics and sports research, have smaller repeatability, likely accounted for to the smaller constraints than in the traditional motor tasks.
Introduction
The aim of this study was to examine if robotic-assisted total knee arthroplasty (RATKA) is cost- and time-effective in terms of implant stock and perioperative parameters, as optimizing ...perioperative efficiency may contribute to value-based care.
Materials and methods
Four hundred thirty-two consecutive patients who received primary total knee arthroplasties (TKAs) from May 2017 to March 2020 in a regional hospital were included in this study. Operating room time (OR time), surgical time, number of trays, insert thickness, and length of stay (LOS) were assessed and compared for a cohort group with navigation-assisted procedures to a group with robotic-assisted procedures (MAKO, Stryker, USA). Prediction of implant size was assessed for the robotic-assisted group. The Mann–Whitney
U
test was used for comparisons between groups when the normality assumption was not met. Categorical variables were assessed using the Fisher’s exact test.
p
< 0.05 was considered statistically significant.
Results
In the RATKA group, we noticed a significant mean reduction of 11 min in total OR time (
p
< 0.001), the use of thinner insert (
p
< 0.001), and a shorter mean length of stay of 1 day (
p
< 0.001). Compared to the navigation group, surgical time was not significantly longer, nor clinically relevant (0.238). In 76.9% of the robotic-assisted cases, the estimated implant size was equal to the final size and in all other cases, the preoperative implant size was oversized.
Conclusion
The introduction of the MAKO robotic-assisted total knee arthroplasty resulted in a gain in operating room time, a thinner and more predictable insert thickness, a shorter length of stay in hospital, and less instrumentation compared to navigation-assisted procedures.
Level of evidence
Level III, Retrospective cohort study.
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