Effect of open wedge high tibial osteotomy on the lateral tibiofemoral compartment in sheep. Part III: analysis of the microstructure of the subchondral bone and correlations with the articular cartilage and meniscus

Residual coronary malformation after tibial shaft fracture alters the contact status of the meniscus and cartilage in the knee joint: a computational study

Objective

The purpose of this study was to evaluate the effect of residual varus/valgus deformity on the mechanical characteristics of the meniscus and cartilage after tibial shaft fracture.

Methods

A finite element model of the lower extremity of a healthy volunteer was constructed from CT and MRI images. The upper and middle tibial fracture models were modified to produce 3°, 5°, and 10° tibial varus/valgus models. For model validation, a patient-specific model with a 10° tibial varus deformity was constructed and simulated under the same boundary conditions.

Results

The contact area and maximum stress of the normal and modified deformity models were similar to those of the reported studies and a patient-specific model. The maximum stress, contact area, and contact force of the medial tibial cartilage in a normal neutral position were 0.64 MPa, 247.52 mm2, and 221.77 N, respectively, while those of the lateral tibial cartilage were 0.76 MPa, 196.25 mm2, and 146.12 N, respectively. From 10° of valgus to 10° of varus, the contact force, contact area, and maximum stress values of the medial tibial cartilage increased, and those of the lateral tibial cartilage gradually decreased. The maximum stress, contact area, and contact force of the medial tibial cartilage in the normal neutral position were 3.24 MPa, 110.91 mm2, and 62.84 N, respectively, while those of the lateral tibial cartilage were 3.45 MPa, 135.83 mm2, and 67.62 N, respectively. The maximum stress of the medial tibial subchondral bone in a normal neutral position was 1.47 MPa, while that of the lateral was 0.65 MPa. The variation trend of the medial/lateral meniscus and subchondral bone was consistent with that of the tibial plateau cartilage in terms of maximum stress, contact area, and contact force.

Conclusion

The residual varus/valgus deformity of the tibia has a significant impact on the mechanical loads exerted on the knee joint. This study provides a mechanical basis and references for the clinical evaluation of tibial fracture reduction and osteotomy for tibial deformity.

Modulation of early osteoarthritis by tibiofemoral re-alignment in sheep

OBJECTIVE

To investigate whether tibiofemoral alignment influences early knee osteoarthritis (OA). We hypothesized that varus overload exacerbates early degenerative osteochondral changes, and that valgus underload diminishes early OA.

METHOD

Normal, over- and underload were induced by altering alignment via high tibial osteotomy in adult sheep (n = 8 each). Simultaneously, OA was induced by partial medial anterior meniscectomy. At 6 weeks postoperatively, OA was examined in five individual subregions of the medial tibial plateau using Kellgren-Lawrence grading, quantification of macroscopic OA, semiquantitative histopathological OA and immunohistochemical type-II collagen, ADAMTS-5, and MMP-13 scoring, biochemical determination of DNA and proteoglycan contents, and micro-computed tomographic evaluation of the subchondral bone.

RESULTS

Multivariate analyses revealed that OA cartilaginous changes had a temporal priority over subchondral bone changes. Underload inhibited early cartilage degeneration in a characteristic topographic pattern (P ≥ 0.0983 vs. normal), in particular below the meniscal damage, avoided alterations of the subarticular spongiosa (P ≥ 0.162 vs. normal), and prevented the disturbance of otherwise normal osteochondral correlations. Overload induced early alterations of the subchondral bone plate microstructure towards osteopenia, including significantly decreased percent bone volume and increased bone surface-to-volume ratio (all P ≤ 0.0359 vs. normal).

CONCLUSION

The data provide high-resolution evidence that tibiofemoral alignment modulates early OA induced by a medial meniscus injury in adult sheep. Since underload inhibits early OA, these data also support the clinical value of strategies to reduce the load in an affected knee compartment to possibly decelerate structural OA progression.

Cartilage Degeneration of the Lateral Compartment of the Knee at Second-Look Arthroscopy Is Associated With Deterioration of 10-Year Clinical Outcomes After Opening-Wedge High Tibial Osteotomy

PURPOSE

To identify the arthroscopic findings associated with deterioration of 10-year clinical outcomes after opening-wedge high tibial osteotomy (OWHTO) in patients with knee osteoarthritis.

METHODS

A total of 114 consecutive knees of 91 patients with knee osteoarthritis who underwent OWHTO between 2007 and 2011 were retrospectively reviewed. Of these patients, those who underwent second-look arthroscopy and were followed up for a minimum of 10 years were enrolled. The Knee Society Score (KSS) and hip-knee-ankle angle were assessed. Cartilage status was graded at the time of osteotomy (first look) and plate removal (second look) according to the International Cartilage Repair Society (ICRS) grading system. The KSS knee subscale score and function subscale score were assessed separately, and on the basis of the changes in each of these scores from 1 to 10 years postoperatively and the minimal clinically important difference (MCID), the patients were divided into 2 groups: deteriorated (deterioration of score ≥ MCID) and non-deteriorated (deterioration of score < MCID).

RESULTS

Sixty-nine knees were included in this study. The mean knee score improved continuously from 48.7 ± 11.3 preoperatively to 86.8 ± 10.3 at 1 year (P < .001), 87.5 ± 9.9 at 5 years (P < .001), and 86.5 ± 10.5 at 10 years (P < .001) postoperatively. The mean function score also improved continuously from 62.5 ± 12.1 preoperatively to 90.7 ± 12.9 at 1 year (P < .001), 91.6 ± 12.1 at 5 years (P < .001), and 88.5 ± 13.1 at 10 years (P < .001) postoperatively. Three knees underwent conversion to total knee arthroplasty within 10 years postoperatively. The deteriorated KSS group showed significantly progressed ICRS grades in the lateral compartment compared with the non-deteriorated KSS group. The ICRS grade in the lateral compartment at second-look arthroscopy was identified as the only significant factor associated with both knee score deterioration (odds ratio, 4.89; P = .03) and function score deterioration (odds ratio, 3.91; P = .03) on multivariable logistic regression analysis.

CONCLUSIONS

The presence of cartilage degeneration of the lateral compartment of the knee at second-look arthroscopy is associated with deterioration of long-term clinical outcomes after OWHTO.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Fixation method can affect posterior tibial slope in opening-wedge high tibial osteotomy: a retrospective study

BACKGROUND

Posterior tibial slope (PTS) alterations following open-wedge high tibial osteotomy (OWHTO) can cause instability and excessive tibial translation in the sagittal plane. These changes can be influenced by the type of fixation. This study aims to compare PTS changes between patients undergoing OWHTO with Puddu plate or TomoFix plate fixation.

METHODS

In this retrospective cohort study, we included 104 knees from 85 patients undergoing OWHTO, with a mean age of 41.98 ± 9.95 years; 51.8% of the participants were male. Seventy-two knees were fixed with Puddu plates, while 32 knees were fixed with TomoFix plates. PTS changes, demographic factors, Cincinnati Knee Rating Score (CKRS), Tegner-Lysholm score (TLS), length of stay (LOS), and complications were evaluated. PTS changes were measured preoperatively, immediately postoperatively, and at the 6-month follow-up.

RESULTS

Demographic factors were similar between the Puddu plate and TomoFix groups. There were no significant differences in preoperative, postoperative, or follow-up PTS measurements between the two groups. PTS changes were not significant in the TomoFix group postoperatively or at follow-up. However, the Puddu plate group showed a significant increase in PTS both postoperatively (P = 0.027) and at follow-up (P = 0.014). CKRS, TLS, LOS, and complications did not significantly differ between the groups.

CONCLUSION

While overall PTS changes did not significantly differ between the Puddu Plate and TomoFix Plate groups, analyzing changes within each group revealed distinct results. TomoFix fixation exhibited nonsignificant PTS changes, while Puddu plate fixation resulted in a significant increase in PTS after surgery and at the 6-month follow-up. Our findings suggest that the choice of fixation may influence PTS changes after OWHTO.

LEVEL OF EVIDENCE

Level III.

Discharging the medial knee compartment: comparison of pressure distribution and kinematic shifting after implantation of an extra-capsular absorber system (ATLAS) and open-wedge high tibial osteotomy-a biomechanical in vitro analysis

PURPOSE

Young and active patients suffering early degenerative changes of the medial compartment with an underlying straight-leg axis do face a therapeutical gap as unloading of the medial compartment cannot be achieved by high tibial osteotomy. Extracapsular absorbing implants were developed to close this existing therapeutical gap. Purpose of the present cadaveric biomechanical study was to compare the unloading effect of the knee joint after implantation of an extra-articular absorber system (ATLAS) in comparison to open-wedge high tibial osteotomy (OW-HTO) under physiological conditions. The hypothesis of the study was that implantation of an extra-capsular absorber results in an unloading effect comparable to the one achievable with OW-HTO.

METHODS

Eight fresh-frozen cadaveric knees were tested under isokinetic flexion-extension motions and physiological loading using a biomechanical knee simulator. Tibiofemoral area contact and peak contact pressures were measured using pressure-sensitive film in the untreated medial compartment. The tibiofemoral superior-inferior, latero-medial translation and varus/valgus rotation were measured with a 3D tracking system Polaris. Pressures and kinematics changes were measured after native testing, ATLAS System implantation and OW-HTO (5° and 10° correction angles) performed with an angular stable internal fixator (TomoFix).

RESULTS

The absorber device decreased the pressure in the medial compartment near full extension moments. Implantation of the ATLAS absorbing system according to the manufacturers' instruction did not result in a significant unloading effect. Deviating from the surgery manual provided by the manufacturer the implantation of a larger spring size while applying varus stress before releasing the absorber resulted in a significant pressure diminution. Contact pressure decreased significantly Δ0.20 ± 0.04 MPa p = 0.044. Performing the OW-HTO in 5° correction angle resulted in significant decreased contact pressure (Δ0.25 ± 0.10 MPa, p = 0.0036) and peak contact pressure (Δ0.39 ± 0.38 MPa, p = 0.029) compared with the native test cycle. With a 10° correction angle, OW-HTO significantly decreased area contact pressure by Δ0.32 ± 0.09 MPa, p = 0.006 and peak contact pressure by Δ0.48 ± 0.12 MPa, p = 0.0654 compared to OW-HTO 5°. Surgical treatment did not result in kinematic changes regarding the superior-inferior translation of the medial joint section. A significant difference was observed for the translation towards the lateral compartment for the ATLAS system Δ1.31 ± 0.54 MPa p = 0.022 and the osteotomy Δ3.51 ± 0.92 MPa p = 0.001. Furthermore, significant shifting varus to valgus rotation of the treated knee joint was verified for HTO 5° about Δ2.97-3.69° and for HTO 10° Δ4.11-5.23° (pHTO 5 = 0.0012; pHTO 10 = 0.0007) over the entire extension cycle.

CONCLUSION

OW-HTO results in a significant unloading of the medial compartment. Implantation of an extra-capsular absorbing device did not result in a significant unloading until the implantation technique was applied against the manufacturer's recommendation. While the clinical difficulty for young and active patients with straight-leg axis and early degenerative changes of the medial compartment persists further biomechanical research to develop sufficient unloading devices is required.

High tibial osteotomy to neutral alignment improves medial knee articular cartilage composition

PURPOSE

The purpose of this study was to: (1) test the hypothesis that HTO improves articular cartilage composition in the medial compartment without adversely affecting the lateral compartment and patella, and; (2) explore associations between knee alignment and cartilage composition after surgery.

METHODS

3T MRI and standing radiographs were obtained from 34 patients before and 1-year after HTO. Articular cartilage was segmented from T2 maps. Mechanical axis angle (MAA), posterior tibial slope, and patellar height were measured from radiographs. Changes in T2 and radiographic measures were assessed using paired t tests, and associations were assessed using Pearson correlation coefficients.

RESULTS

The mean (SD) MAA before and after HTO was - 6.5° (2.4) and 0.6° (3.0), respectively. There was statistically significant shortening [mean (95%CI)] of T2 in the medial femur [- 2.8 ms (- 4.2; - 1.3), p < 0.001] and medial tibia [- 2.2 ms (- 3.3; - 1.0), p < 0.001], without changes in the lateral femur [- 0.5 ms (- 1.6; 0.6), p = 0.3], lateral tibia [0.2 ms (- 0.8; 1.1), p = NS], or patella [0.5 ms (- 1.0; 2.1), p = NS). Associations between radiographic measures and T2 were low. 23% of the increase in lateral femur T2 was explained by postoperative posterior tibial slope (r = 0.48).

CONCLUSION

Performing medial opening wedge HTO without overcorrection improves articular cartilage composition in the medial compartment of the knee without compromising the lateral compartment or the patella. Although further research is required, these results suggest HTO is a disease structure-modifying treatment for knee OA.

Axial alignment is a critical regulator of knee osteoarthritis

Although osteoarthritis (OA), a leading cause of disability, has been associated with joint malalignment, scientific translational evidence for this link is lacking. In a clinical case study, we provide evidence of osteochondral recovery upon unloading symptomatic isolated medial tibiofemoral knee OA associated with varus malalignment. By mapping response correlations at high resolution, we identify spatially complex degenerative changes in cartilage after overloading in a clinically relevant ovine model. We further report that unloading diminishes OA cartilage degeneration and alterations of critical parameters of the subchondral bone plate in a similar topographic fashion. Last, therapeutic unloading shifted the articular cartilage and subchondral bone phenotype to normal and restored several physiological correlations disturbed in neutral and varus OA, suggesting a protective effect on the integrity of the entire osteochondral unit. Collectively, these findings identify modifiable trajectories with considerable translational potential to reduce the burden of human OA.

The Effect of Body Mass Index and Metformin on Matrix Gene Expression in Arthritic Primary Human Chondrocytes

OBJECTIVE

Obesity is a known risk factor for knee osteoarthritis (OA). Diabetes has been associated with progression of OA and metformin is the first-line treatment in type 2 diabetes. The effect of the body mass index (BMI) and metformin on the expression of certain matrix genes in human chondrocytes is unclear. The purpose of this study was to investigate the effect of BMI and metformin on the expression of matrix genes in primary human chondrocytes.

DESIGN

Adult female patients undergoing knee arthroplasty for end-stage OA were enrolled. Primary chondrocytes were cultivated and stimulated with metformin. Matrix gene expression was analyzed using polymerase chain reaction. Clinical data were used in multivariable regression models to assess the influence of BMI and metformin stimulation on gene expression.

RESULTS

A total of 14 patients were analyzed. BMI was a predictor of increased expression in ADAMTS5 (β = -0.11, P = 0.03). Metformin slightly reduced expression in ADAMTS5 (β = 0.34, P = 0.04), HIF-1a (β = 0.39, P = 0.04), IL4 (β = 0.30, P = 0.02), MMP1 (β = 0.47, P < 0.01), and SOX9 (β = 0.37, P = 0.03). The hip-knee-ankle angle and proton pump inhibitors (PPIs) intake were associated with reduced SOX9 expression (β = 0.23, P < 0.01; β = 2.39, P < 0.01). Higher C-reactive protein (CRP) levels were associated with increased MMP1 expression (β = -0.16, P = 0.02).

CONCLUSION

We found that BMI exerts a destructive effect via induction of ADAMTS5. Metformin reduced the expression of catabolic genes ADAMTS5 and MMP1 and might play a role in disease prevention. Limb malalignment and PPI intake was associated with a reduced expression of SOX9, and higher CRP levels correlated with increased MMP1 expression, indicating a destructive process.

Analysis of spatial osteochondral heterogeneity in advanced knee osteoarthritis exposes influence of joint alignment

Osteoarthritis (OA) is considerably affected by joint alignment. Here, we investigate the patterns of spatial osteochondral heterogeneity in patients with advanced varus knee OA together with clinical data. We report strong correlations of osteochondral parameters within individual topographical patterns, highlighting their fundamental and location-dependent interactions in OA. We further identify site-specific effects of varus malalignment on the lesser loaded compartment and, conversely, an unresponsive overloaded compartment. Last, we trace compensatory mechanisms to the overloaded subarticular spongiosa in patients with additional high body weight. We therefore propose to consider and to determine axial alignment in clinical trials when selecting the location to assess structural changes in OA. Together, these findings broaden the scientific basis of therapeutic load redistribution and weight loss in varus knee OA.

[Relevance of meniscus loss for the progression of osteoarthritis and treatment options for early arthritis]

Meniscal tears are still one of the most frequent lesions in the knee joint. The relevance of meniscus loss for the development of osteoarthritis is undisputed. Meniscus repair, replacement and transplantation play an important role in the treatment of early arthritis, especially when they are a part of a master plan including alignment correction, stabilization and cartilage surgery, if needed. Scientific data show evidence concerning the protection of osteoarthritis, even though a lack of studies including comparison groups has to be admitted.

Comparative anatomy and morphology of the knee in translational models for articular cartilage disorders. Part I: Large animals

BACKGROUND

The human knee is a complex joint, and affected by a variety of articular cartilage disorders. Large animal models are critical to model the complex disease mechanisms affecting a functional joint. Species-dependent differences highly affect the results of a pre-clinical study and need to be considered, necessitating specific knowledge not only of macroscopic and microscopic anatomical and pathological aspects, but also characteristics of their individual gait and joint movements.

METHODS

Literature search in Pubmed.

RESULTS AND DISCUSSION

This narrative review summarizes the most relevant anatomical structural and functional characteristics of the knee (stifle) joints of the major translational large animal species, comprising dogs, (mini)pigs, sheep, goats, and horses in comparison with humans. Specific characteristics of each species, including kinematical gait parameters are provided. Considering these multifactorial dimensions will allow to select the appropriate model for answering the research questions in a clinically relevant fashion.

Topographic modeling of early human osteoarthritis in sheep

Articular cartilage damage occurring during early osteoarthritis (OA) is a key event marking the development of the disease. Here, we modeled early human OA by gathering detailed spatiotemporal data from surgically induced knee OA development in sheep. We identified a specific topographical pattern of osteochondral changes instructed by a defined meniscal injury, showing that both cartilage and subchondral bone degeneration are initiated from the region adjacent to the damage. Alterations of the subarticular spongiosa arising locally and progressing globally disturbed the correlations of cartilage with subchondral bone seen at homeostasis and were indicative of disease progression. We validated our quantitative findings against human OA, showing a similar pattern of early OA correlating with regions of meniscal loss and an analogous late critical disturbance within the entire osteochondral unit. This translational model system can be used to elucidate mechanisms of OA development and provides a roadmap for investigating regenerative therapies.

Improved clinical outcome after medial open-wedge osteotomy despite cartilage lesions in the lateral compartment

High tibial medial open-wedge osteotomy (HTO) is an established treatment option for cartilage lesions in the medial compartment. It was this study’s aim to evaluate the effect of asymptomatic single or kissing lesions in the lateral compartment on functional outcome after medial open-wedge osteotomy. A total of 156 patients were enrolled in this retrospective study. All patients underwent HTO due to a varus deformity and a symptomatic cartilage lesion or osteoarthritis in the medial compartment. We acquired preoperative Lysholm and VAS Scores. Each open-wedge osteotomy was preceded by diagnostic arthroscopy to ensure the compartments were thoroughly documented and diagnosed. Cartilage lesions in the lateral compartment were evaluated, and three groups created according to their individual characteristics: group A (no cartilage lesion, n = 119), group B (single cartilage lesion, n = 16) and group C (kissing lesions, n = 21). Cartilage lesions were graded according to the Outerbridge classification, The functional postoperative outcome was determined by relying on several parameters (VAS Score, Lysholm, KOOS, WOMAC Score). Pre- and postoperative long-leg axis views were analyzed via special planning software (mediCAD, Hectec GmbH Germany). Mean follow-up was at 69.0 ± 30.3 months after surgery (range 22 to 121 months). There were no significant differences between the three groups in the correction angle chosen (p = 0.16). Regarding the outcome parameters, group A attained the best results in the WOMACpain Score (p = 0.03) and WOMACfunction Score (p = 0.05). A higher Outerbridge-Score of cartilage lesions in the lateral compartment was associated with a higher (i.e., worse) WOMACpain Score (p = 0.018) and WOMACfunction Score (p = 0.033). In all the groups (A, B, and C), HTO led to a significant improvement in the Lysholm Score (p < 0.001) and to a decrease in pain level (VAS Score; p < 0.001). Conclusion: Valgus high tibial osteotomy leads to reduced pain and improved functional outcome scores, even in patients with pre-existing asymptomatic single or corresponding cartilage lesions in the lateral compartment. In case of severe cartilage lesions in the lateral compartment, surgeons should consider that clinical outcome worsens depending on the Outerbridge Score.

[Meniscal lesion. A pre-osteoarthritic condition of the knee joint]

BACKGROUND

A close relationship between meniscal damage and articular cartilage exist. Likewise, (partial) meniscectomy may lead to the development of osteoarthritis (OA).

OBJECTIVES

With a special emphasis on therapeutic consequences for orthopaedic surgeons, the structural and functional relationship between meniscal tears/extrusion and cartilage loss, and/or the effect of meniscectomy or meniscal repair on the development of OA, are emphasized.

MATERIALS AND METHODS

A selective literature review with implementation of own research findings.

RESULTS

The close topographical and functional interplay between the menisci and the tibiofemoral cartilage is the basis for the clinically important relationship between meniscal damage and cartilage degeneration. In particular, due to its close connection to tibiofemoral OA, a degenerative meniscal lesion represents a pre-osteoarthritic condition. Meniscus extrusion is also often associated with tibiofemoral OA. Even large cartilage defects can cause meniscus lesions. Partial meniscectomy is strongly associated with the incidence and risk of progression of OA. Clinical results are particularly problematic after partial resection of the lateral meniscus. Although the use of arthroscopic partial resection for degenerative meniscal lesions has been controversially discussed, no long-term studies are available. A large number of studies emphasize the medium-term value of meniscus reconstruction compared to partial meniscus resection. Combined meniscus and cartilage damage are complex cases, and the value of a simultaneous therapy remains unclear.

CONCLUSIONS

Preserving the meniscus is the first step towards cartilage repair. Randomized and controlled studies will provide better information on the long-term outcomes of meniscal resection and repair with regard to OA development.

Advances in modern osteotomies around the knee : Report on the Association of Sports Traumatology, Arthroscopy, Orthopaedic surgery, Rehabilitation (ASTAOR) Moscow International Osteotomy Congress 2017

Corrective lower limb osteotomies are innovative and efficient therapeutic procedures for restoring axial alignment and managing unicompartmental knee osteoarthritis. This review presents critical insights into the up-dated clinical knowledge on osteotomies for complex posttraumatic or congenital lower limb deformities with a focus on high tibial osteotomies, including a comprehensive overview of basic principles of osteotomy planning, biomechanical considerations of different implants for osteotomies and insights in specific bone deformity correction techniques. Emphasis is placed on complex cases of lower limb osteotomies associated with ligament and multiaxial instability including pediatric cases, computer-assisted navigation, external fixation for long bone deformity correction and return to sport after such osteotomies. Altogether, these advances in the experimental and clinical knowledge of complex lower limb osteotomies allow generating improved, adapted therapeutic regimens to treat congenital and acquired lower limb deformities.

Longitudinal changes in subchondral bone structure as assessed with MRI are associated with functional outcome after high tibial osteotomy

OBJECTIVES

The primary objective of this study was to evaluate the effects of high tibial osteotomy (HTO) on subchondral bone structure assessed with magnetic resonance (MR)-based trabecular bone imaging and the correlations of these effects with functional outcome and clinical symptoms.

METHODS

Patients with varus malalignment (6.2±2.2°) and without a history of knee surgery (n=22; 3 women; 48.7±10.3 years) were included into this prospective study. 1.5T MR imaging was performed before and on average 1.5 years after HTO (amount of correction 4.7±2.5°) and histomorphometric parameters of the trabecular bone were calculated for the medial/ lateral tibia and femur. Functional outcome was assessed with validated scores focusing on sports activity including the Lysholm Score, Tegner Activity Scale and the adapted Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score.

RESULTS

Apparent trabecular number significantly decreased in all compartments of the tibiofemoral joint when comparing values before and on average 1.5 years after HTO (P<0.05 for all). Decrease in apparent trabecular number was significantly higher within the medial tibia compared to the lateral compartment (mean difference -0.24 mm^-1 (95% confidence interval (CI): -0.33, -0.14 mm^-1); P<0.001). Apparent trabecular bone thickness significantly increased within 1.5 years after HTO in the lateral femur (P=0.002) and tibia (P <0.001). The Lysholm Score and Tegner Scale demonstrated an improvement of functional outcome, and the adapted WOMAC demonstrated an improvement of pain, stiffness and physical function within 1.5 years after HTO (P<0.01), with the improvement of WOMAC correlating significantly with changes in trabecular bone thickness within the medial tibia (r= -0.48; P=0.01).

CONCLUSION

These findings indicate a reversal of the previous subchondral bone alterations in patients with varus malalignment after undergoing HTO, while pronounced subchondral changes were associated with a better functional outcome.

LEVEL OF EVIDENCE

3.

Large correction in opening wedge high tibial osteotomy with resultant joint-line obliquity induces excessive shear stress on the articular cartilage

PURPOSE

The purpose of this study was to analyse the resultant stress induced by joint-line obliquity after HTO for varus knee deformity using a three-dimensional (3D) finite element model analysis.

METHODS

The geometrical bone data used in this study were derived from commercially available human bone digital anatomy media. The 3D knee models were developed using 3D computer-aided design software. The articular surface was overlaid with a 2-mm-thick cartilage layer for both femoral and tibial condyles. Ligament structures were simulated based on properties reported in previous anatomical studies. Regarding the loading condition, isolated axial loads of 1200 N with lateral joint-line inclinations of 2.5°, 5°, 7.5°, and 10° in reference to the horizontal axis were applied to the femur to simulate the mechanical environment in a knee with joint-line obliquity.

RESULTS

A steep rise of shear stress in the medial compartment was noted in the model with obliquity of 5° or more. This laterally directed shear stress exhibited an incremental increase in accordance with the obliquity angle. The maximum shear stress value in the medial cartilage increased from 1.6 MPa for the normal knee to 3.3, 5.2, and 7.2 MPa in the joint-line obliquity models with 5°, 7.5°, and 10° of obliquity, respectively.

CONCLUSIONS

The effects of HTO for varus knee deformity on the amount/distribution of stresses in the articular cartilage were analysed using a 3D finite element model. It was shown that joint-line obliquity of more than 5° induced excessive shear stress in the tibial articular cartilage. A large amount of correction in OWHTO with a resultant joint-line obliquity of 5° or more may induce detrimental stress to the articular cartilage. Double-level osteotomy should be considered as a surgical option in this situation.

High tibial osteotomy accelerates lateral compartment osteoarthritis in discoid meniscus patients

PURPOSE

The valgus high tibial osteotomy (HTO) in patients with medial osteoarthritis and discoid lateral meniscus can result in increased load on the lateral compartment and hence a higher chances of tear. This may accelerate the progression of osteoarthritis on lateral compartment. We, therefore, carried out the case control study with a hypothesis that an HTO would accelerate the progression of osteoarthritis (OA) on lateral compartment in patients with complete discoid meniscus.

METHODS

The records of all patients with open wedge HTO from 2008 to 2012 were evaluated for complete lateral discoid meniscus. The patient who had a valgus HTO with or without partial meniscectomy for medial compartmental OA was included for this study. Cases to control were chosen to match age, body mass index (BMI), pre-operative osteoarthritis grade, and deformity angles in ratio 1:2. Patient's records were studied for demographic data, clinical examination records, and pre-operative knee functional scores and radiological scores and were compared with post-operative data.

RESULTS

Thirty-six patients out of 674 patients, who underwent an HTO, consisted of discoid meniscus group. 72 patients were chosen as control group. Four patients showed progression of OA on the lateral compartment in discoid group compared to none in control group. Although control groups showed a little bit better functional outcomes, there were no statistical differences between two groups (n.s.).

CONCLUSION

The high tibial osteotomy could result in accelerated lateral compartment osteoarthritis in patients with complete discoid meniscus, and the procedure should be used with caution in such patients.

LEVEL OF EVIDENCE

IV.

Meniscal pathologies on MRI correlate with increased bone tracer uptake in SPECT/CT

OBJECTIVES

To assess the relationship of subchondral bone tracer uptake (BTU) on SPECT/CT and meniscal pathologies on MRI in patients with painful knees.

METHODS

Twenty-five patients who had MRI and SPECT/CT within 3 months without knee surgery or grade ≥3 cartilage lesions were prospectively included. Maximum values of each subchondral femorotibial area were quantified and a ratio was calculated in relation to a femoral shaft reference region, which represented the BTU background activity. Meniscal lesions were graded (intact/degeneration/tear) and meniscal extrusion (no/yes) was assessed using MRI by two musculoskeletal radiologists blinded to the SPECT/CT findings. One-tailed Spearman correlations served for statistics (p < 0.05).

RESULTS

Knees with meniscal degeneration or tear showed a significantly higher BTU in the medial femorotibial compartment (p = 0.045) when compared to intact menisci. Meniscal degeneration was associated with an increased BTU in the lateral femorotibial compartment; however, this was not statistically significant (p = 0.143). Patients with an extruded meniscus showed significantly higher BTU compared to a non-extruded meniscus (p < 0.020).

CONCLUSIONS

Medial femorotibial BTU in SPECT/CT was associated with meniscal pathologies. Highest BTU was found in patients with meniscal tears. SPECT/CT appears to be a useful imaging modality to identify patients with overloading or early osteoarthritis.

KEY POINTS

• Meniscal degeneration and tears correlate significantly with increased BTU using SPECT/CT. • Medial meniscus extrusion is associated with an increased BTU in SPECT/CT. • SPECT/CT allows detection of overloading and early osteoarthritis.

Clinical Management in Early OA

Knee osteoarthritis affects an important percentage of the population throughout their life. Several factors seem to be related to the development of knee osteoarthritis including genetic predisposition, gender, age, meniscal deficiency, lower limb malalignments, joint instability, cartilage defects, and increasing sports participation. The latter has contributed to a higher prevalence of early onset of knee osteoarthritis at younger ages with this active population demanding more consistent and durable outcomes. The diagnosis is complex and the common signs and symptoms are often cloaked at these early stages. Classification systems have been developed and are based on the presence of knee pain and radiographic findings coupled with magnetic resonance or arthroscopic evidence of early joint degeneration. Nonsurgical treatment is often the first-line option and is mainly based on daily life adaptations, weight loss, and exercise, with pharmacological agents having only a symptomatic role. Surgical treatment shows positive results in relieving the joint symptomatology, increasing the knee function and delaying the development to further degenerative stages. Biologic therapies are an emerging field showing early promising results; however, further high-level research is required.

Comparison of the efficiency of an extra-articular absorber system and high tibial osteotomy for unloading the medial knee compartment: an in vitro study

PURPOSE

The unloading effect of an extra-articular absorber system on the knee joint medial compartment was compared with high tibial osteotomy (HTO) under physiological conditions in vitro.

METHODS

Seven fresh-frozen cadaveric knees were used to test isokinetic flexion-extension motions under physiological loading using a biomechanical knee simulator. Tibiofemoral area contact and peak contact pressures were measured using pressure-sensitive film in the untreated medial compartment. Pressures were measured after KineSpring System implantation and HTO (5° and 10° correction angles) performed with an angular-stable internal fixator (Tomofix).

RESULTS

Implantation of the unloading device resulted in significantly decreased medial compartment area contact pressure (Δ0.02 ± 0.01 MPa, p = 0.001) and peak contact pressure (Δ0.3 ± 0.1 MPa, p = 0.001) compared with the first test cycle results in the untreated knee. HTO significantly decreased the pressure (p = 0.001). Compared with the first test cycle, HTO (5° correction angle) decreased the mean contact pressure by Δ0.03 ± 0.01 MPa and peak contact pressure by Δ0.3 ± 0.01 MPa. With a 10° correction angle, HTO decreased contact pressure by Δ0.04 ± 0.02 MPa and peak contact pressure by Δ0.4 ± 0.1 MPa compared with that at the 5° correction angle.

CONCLUSION

Implantation of an extra-capsular unloading device resulted in a significant unloading effect on the medial compartment comparable to that achieved with HTO at 5° and 10° correction angles. Thus, implantation of an extra-articular, extra-capsular absorber could become the method of choice when treating patients with unicompartmental osteoarthritis that cannot be adequately treated by HTO because of their straight-leg axis.

Progression of medial compartmental osteoarthritis 2-8 years after lateral closing-wedge high tibial osteotomy

PURPOSE

The primary purpose of this study is to investigate the progression of medial osteoarthritis (OA) following lateral closing-wedge high tibial osteotomy (HTO). Secondary outcomes included functional and pain scores.

METHODS

This prospective cohort study analysed 298 patients treated with lateral closing-wedge HTO surgery for medial compartmental OA. OA progression was measured by comparing the minimum joint space width (mJSW) and Kellgren-Lawrence (KL) score on radiographs preoperatively and postoperatively. The WOMAC score and NRS score for pain were obtained preoperatively and postoperatively to assess secondary outcomes. Failure was defined as revision surgery; survival was estimated.

RESULTS

Mean follow-up was 5.2 ± 1.8 years (range 2-8.5). Mean preoperative mJSW was 3.4 ± 1.6 mm, which changed nonsignificantly (p = 0.51) to 3.4 ± 1.7 mm postoperatively. Mean annual joint space narrowing was 0.02 ± 0.34 mm/year. Progression to 1 KL grade or more was seen in 132 (44 %) patients, and annual risk of KL progression was 8.6 %. No KL progression was seen in 56 % of patients. Mean NRS decreased from 7.3 ± 1.5 to 3.5 ± 2.5 (p < 0.001). WOMAC scores decreased from 48.0 ± 17.2 to 23.6 ± 19.7 (p < 0.001). Failure was seen in 21 patients.

CONCLUSION

Compared to demographic data in the literature, valgus high tibial osteotomy seems to reduce the progression of OA, reduces pain and improves knee function in patients with medial compartment OA and a varus alignment.

LEVEL OF EVIDENCE

III.

Osteotomy configuration of the proximal wedge and analysis of the affecting factors in the medial open-wedge high tibial osteotomy

PURPOSE

The purposes of this study were (1) to confirm the disparity of the measured thickness at the lateral hinge between anterior-posterior (AP) radiograph and 3D CT image, (2) to evaluate the affecting factors, and (3) to evaluate the differences between uniplanar and biplanar osteotomies.

METHODS

From 2012 to 2014, a prospective comparative study was performed with 30 patients who received uniplanar osteotomy (group I) and 35 patients who received biplanar osteotomy (group II). For measurement of the proximal wedge, postoperative AP radiograph and 3D CT images were used. In the AP radiograph, medial and lateral bony bridge thicknesses were measured. In the 3D CT, the anterior and posterior images parallel to the coronal plane were selected for the evaluation. Coronal osteotomy slope was measured with the anterior image of the 3D CT scan. Sagittal osteotomy slope was measured with the sagittal section of the CT scan.

RESULTS

Differences between the lateral bony bridge thicknesses measured in AP radiograph and the posterolateral posterolateral bony bridge thicknesses measured in 3D CT were statistically significant in both groups. Negative correlation was observed in the biplanar osteotomy group. Differences of the sagittal osteotomy slope from the native tibial slope showed negative correlation in the biplanar osteotomy group.

CONCLUSION

Thickness of the posterolateral bony bridge was smaller compared to the observed thickness on the AP radiograph image that is routinely used for the follow-up. The thickness would be getting smaller if osteotomy is performed with an abrupt angle on the coronal plane and reverse slope on the sagittal plane. Therefore, osteotomy with abrupt angle on the coronal plane and reverse slope on the sagittal plane should be avoided for the proper thickness of the posterolateral bony bridge.

LEVEL OF EVIDENCE

III.

Factors affecting cartilage repair after medial opening-wedge high tibial osteotomy

PURPOSE

This study documented the healing potential of degenerated articular cartilage after opening-wedge valgus high tibial osteotomy (HTO) in patients with osteoarthritis of the knee. It was hypothesized that regeneration of articular cartilage is affected by several factors, including preoperative cartilage degeneration grade, difference between the medial femoral condyle (MFC) and the medial tibial condyle (MTC), and postoperative knee alignment.

METHODS

Medial opening-wedge valgus HTO was performed in 131 knees of 100 patients (mean age 66 ± 7.7 years). Initial arthroscopy was performed at the time of HTO, and a second-look arthroscopy was performed at the time of plate removal (20.8 ± 6.5 months after HTO). Status of articular cartilage was assessed according to the ICRS grade. Cartilage regeneration was also evaluated by the presence of newly formed cartilaginous tissue. All subjects were followed up postoperatively at 2 years for assessment of clinical and radiographic outcomes.

RESULTS

The number of subjects in ICRS grade 1/2/3/4 was significantly altered from 0/11/53/67 preoperatively to 14/21/56/40 postoperatively in the MFC (P < 0.05) and 0/12/62/57 preoperatively to 9/24/64/34 postoperatively in the MTC (P < 0.05). Newly formed cartilaginous tissue was found in 71 % of MFCs and 51 % of MTCs. Incidence of cartilage regeneration was significantly higher in lower BMI cases, MFC, preoperatively advanced ICRS grade and overcorrected knees. Age, gender and clinical outcomes did not affect cartilage regeneration.

CONCLUSION

Cartilage regeneration in degenerated articular cartilage is induced after opening-wedge valgus HTO, which is affected by BMI, the difference between the MFC and MTC, preoperative cartilage degeneration grade, and postoperative limb alignment. Therefore, patient selection by BMI rather than age, and surgical techniques maintaining valgus knee alignment should be considered for cartilage regeneration.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Is overcorrection preferable for repair of degenerated articular cartilage after open-wedge high tibial osteotomy?

PURPOSE

This study was performed to determine whether the overcorrected knee could obtain a higher ratio of articular cartilage repair in the medial compartment of the femorotibial joint after open-wedge high tibial osteotomy (HTO). The hypothesis of the study was that overcorrected knees had a higher ratio of articular cartilage repair than moderately corrected knees.

METHODS

A total of 71 knees that underwent arthroscopy to evaluate the articular cartilage during open-wedge HTO and second-look arthroscopy were reviewed. The articular cartilage was classified as no repair or repair according to Koshino et al. Overcorrection was defined as knees with femorotibial angle ≤166°.

RESULTS

Second-look arthroscopy was performed 410 ± 64 days after HTO. Based on arthroscopic observations, 45 knees (63.4 %) showed no repair and 26 knees (36.6 %) showed repair. In terms of the ratio of cartilage repair, there was no difference between overcorrected knees with mean femorotibial angle of 165° ± 1° and moderately corrected knees with mean femorotibial angle of 170° ± 2° (n.s.).

CONCLUSIONS

No significant differences were found in the ratio of cartilage repair between overcorrected and moderately corrected knees.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Load distribution in early osteoarthritis

Total knee replacement is an accepted standard of care for the treatment of advanced knee osteoarthritis with good results in the vast majority of older patients. The use in younger and more active populations, however, remains controversial due to concerns over activity restrictions, implant survival, and patient satisfaction with the procedure. It is in these younger patient populations that alternatives to arthroplasty are increasingly being explored. Historically, osteotomy was utilized to address unicompartmental pain from degeneration and overload, for example, after meniscectomy. Utilization rates of osteotomy have fallen in recent years due to the increasing popularity of partial and total knee arthroplasty. This article explores the indications and outcomes of traditional unloading osteotomy, as well as newer options that are less invasive and offer faster return to function.

The role of meniscal tissue in joint protection in early osteoarthritis

It is widely accepted that partial meniscectomy leads to early onset of osteoarthritis (OA). A strong correlation exists between the amount and location of the resected meniscus and the development of degenerative changes in the knee. On the other hand, osteoarthritic changes of the joint alter the structural and functional integrity of meniscal tissue. These alterations might additionally compromise the limited healing capacity of the meniscus. In young, active patients without cartilage damage, meniscus therapy including partial meniscectomy, meniscus suture, and meniscus replacement has proven beneficial effects in long-term studies. Even in an early osteoarthritic milieu, there is a relevant regenerative potential of the meniscus and the surrounding cartilage. This potential should be taken into account, and meniscal surgery can be performed with the correct timing and the proper indication even in the presence of early OA.

Large animal models in experimental knee sports surgery: focus on clinical translation

Large animal models play a crucial role in sports surgery of the knee, as they are critical for the exploration of new experimental strategies and the clinical translation of novel techniques. The purpose of this contribution is to provide critical aspects of relevant animal models in this field, with a focus on paediatric anterior cruciate ligament (ACL) reconstruction, high tibial osteotomy, and articular cartilage repair. Although there is no single large animal model strictly replicating the human knee joint, the sheep stifle joint shares strong similarities. Studies in large animal models of paediatric ACL reconstruction identified specific risk factors associated with the different surgical techniques. The sheep model of high tibial osteotomy is a powerful new tool to advance the understanding of the effect of axial alignment on the lower extremity on specific issues of the knee joint. Large animal models of both focal chondral and osteochondral defects and of osteoarthritis have brought new findings about the mechanisms of cartilage repair and treatment options. The clinical application of a magnetic device for targeted cell delivery serves as a suitable example of how data from such animal models are directly translated into in clinical cartilage repair. As novel insights from studies in these translational models will advance the basic science, close cooperation in this important field of clinical translation will improve current reconstructive surgical options and open novel avenues for regenerative therapies of musculoskeletal disorders.

[Structural changes in the lateral tibiofemoral compartment after high tibial osteotomy]

BACKGROUND

Valgus high tibial osteotomy (HTO) increases the pressure in the lateral tibiofemoral compartment.

OBJECTIVE

The purpose of this work is to provide an overview about current knowledge on the effect of HTO on the lateral tibiofemoral osteochondral unit and lateral meniscus.

MATERIALS AND METHODS

Studies in translational models on the effect of medial opening wedge HTO on the lateral tibiofemoral osteochondral unit and lateral meniscus are reviewed and placed in the clinical perspective. Emphasis is placed on specific correlations between topographical alterations of the cartilage, subchondral bone, and meniscus in the lateral tibiofemoral compartment.

DISCUSSION

Specific topographical relationships exist in the central region between the articular cartilage and subchondral bone plate thickness, and in the submeniscal periphery between the articular cartilage and lateral meniscus, emphasizing the important protective role of the lateral meniscus. Following standard correction, the pressure increase in the lateral compartment following valgus HTO does not induce significant structural changes in the lateral tibiofemoral compartment. A higher increase in pressure following valgus overcorrection induces adaptive changes in the lateral compartment, reflected by an increased specific bone surface (BS/BV) in the subarticular spongiosa compared with unloading by varisation. Valgus overcorrection also leads to a decrease in the number of cells in the red-red (peripheral) zone of the middle third of the lateral menisci, without structural changes.

RESULTS

In conjunction with the clinical data these results show that opening wedge HTO is a safe procedure for the lateral tibial osteochondral unit and the lateral meniscus.