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

Focal cartilage defects of the lateral compartment do influence the outcome after high tibial valgus osteotomy

INTRODUCTION

High tibial medial open-wedge valgus osteotomy (HTO) is a well-established procedure for unicompartimental medial osteoarthritis of the young and active patient. However, the influence of cartilage defects of the lateral compartment on the total outcome remains obscure.

METHODS

From 2005 to 2012, a total of 63 patients underwent HTO for medial osteoarthritis of the knee at a single university orthopaedic center. Baseline data as well as intraoperative findings, including the grade and location of cartilage lesions, were evaluated retrospectively. Two groups were formed regarding the integrity of the lateral tibiofemoral compartment as measured by the Outerbridge score (group A: no lateral cartilage defects, group B: mild to moderate lateral cartilage defects). Functional outcome was assessed using the Knee and Osteoarthritis Outcome Score (KOOS), including its five subscores.

RESULTS

Comparing pre- and postoperative data, we identified an overall benefit of the HTO procedure as measured by the KOOS. Group A (no lateral cartilage defects) showed an increase in all five KOOS subscores (p = 0.00-0.01), whereas for group B (mild to moderate lateral cartilage defects), only two KOOS subscores revealed a significant increase (p = 0.03-0.04). There was also a statistically significant difference in the total KOOS score with higher values for group A at the postoperative visit. Cartilage defects with a higher Outerbridge score were associated with lower postoperative KOOS subscores.

DISCUSSION

Mild to moderate cartilage defects of the lateral compartment humble the total outcome after HTO procedure. Thus, indication for HTO should be made very carefully if any degree of lateral cartilage degeneration is present.

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.

The medial open-wegde osteotomy generates progressive intrameniscal integrity changes in the lateral knee compartment: a prospective MR-assessment after valgic osteotomy in the varus gonarthritic knee

PURPOSE

Meniscal changes in the lateral knee compartment after medial-opening high tibial osteotomy (HTO) with valgic overcorrection have not been investigated clinically with magnetic resonance imaging (MRI). The hypothesis of this study was that HTO with valgic overcorrection affects the lateral compartment due to the change in the bearing axis and the shift in the pressure load from the medial to the lateral compartment. This should lead to an accelerated degeneration of the lateral compartment.

METHODS

Twenty-four patients (mean age, 45.7 ± 7.6 years) were prospectively and longitudinally monitored with MRI after medial-opening high tibial osteotomy. The degeneration of the meniscus was assessed at the anterior horn, pars intermedia, and posterior horn using the Stoller classification. The morphological changes were also assessed at the anterior horn, pars intermedia, and posterior horn using the relative vertical and transverse diameters of the examined part of the meniscus, according to the ratio maximal meniscal diameter/maximal tibial width. These parameters were analyzed preoperatively and at follow-up (mean 5.3 ± 1.5 years after surgery).

RESULTS

During the follow-up period, there were no significant morphological changes in either the anterior horn, pars intermedia, or posterior horn. Nor were there any correlations between the morphological parameters, bodyweight, and the follow-up period. Despite these findings, an MRI evaluation showed progressive degeneration in every part of the meniscus according to the Stoller classification, and this was significant at the anterior horn (p < 0.01), pars intermedia (p = 0.021), and posterior horn (p < 0.01).

CONCLUSION

High tibial osteotomy did not lead to morphological changes in the external meniscus over a follow-up period of 5.3 ± 1.5 years. However, progressive degeneration of the meniscus was observed in the imaging data. Further research is required to confirm the observed degeneration and to evaluate the consequences of the observed degeneration.

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.