Subchondral bone cysts regress after correction of malalignment in knee osteoarthritis: comply with Wolff's law

Deformity Correction: Do Osteochondral Lesion of the Talus and Tibia Change After Realignment Surgery?

Malalignment of the lower limb, distal tibia, foot, and hindfoot can all contribute to altered biomechanics in the ankle joint, resulting in increased focal pressure. The development of some osteochondral lesions of the ankle joint may share a similar pathophysiology, where eccentric loading to the talus or tibia within the ankle joint can lead to cartilage injury or adaptive changes. While the association between malalignment and the development of osteochondral lesions of the ankle joint may seem intuitive, the impact of realignment procedures on these lesions and patient symptoms remains a relatively underexplored topic in the literature. A comprehensive understanding of the potential role of realignment surgery in managing osteochondral lesions of the talus and tibia is crucial for advancing our knowledge of this challenging pathologic condition.

Medial Cystic Osteochondral Lesions of the Talus Exhibited Lower Sports Levels, Higher Cyst Presence Rate, and Inferior Radiological Outcomes Compared With Lateral Lesions Following Arthroscopic Bone Marrow Stimulation

PURPOSE

To compare the patient-reported outcomes and radiologic outcomes of the patients with medial and lateral cystic osteochondral lesions of the talus (OLTs) following bone marrow stimulation (BMS).

METHODS

Patients with cystic OLTs who underwent BMS between January 2016 and February 2021 were retrospectively analyzed, and the minimum follow-up time was more than 24 months. Patients were paired in a 1:1 ratio (medial cystic OLT [MC-OLT]/lateral cystic OLT [LC-OLT]) based on the OLT area within 30 mm2, follow-up within 1 year, age within 5 years, and ligament surgery (yes/no). The visual analog scale and Foot and Ankle Ability Measure (FAAM)-Activities of Daily Life and Sports scores were assessed preoperatively and postoperatively. The magnetic resonance observation of cartilage repair tissue scores and presence of cysts after BMS were also evaluated. Additionally, the receiver operating characteristic curve was performed.

RESULTS

The matched patients were divided into the MC-OLT (n = 31, 43.35 ± 12.32 months) and LC-OLT groups (n = 31, 43.32 ± 14.88 months, P = .986). Thirty patients of each group achieved a power of 80% and an α = 0.05 in this study. The MC-OLT group showed significantly less improvement in FAAM-Activities of Daily Life and sports scores (P = .034, P < .001, respectively), lower magnetic resonance observation of cartilage repair tissue scores (80.80 ± 11.91 vs 86.00 ± 8.50, P = .010), and higher presence rate of cysts after BMS (45.16% vs 16.12%, P = .013). Regarding FAAM sports scores, the LC-OLT group had significantly more patients exceeding the minimal clinically important difference (80.64% vs 51.61%, P = .031). Furthermore, an OLT depth of 7.23 mm (sensitivity: 78.6%; specificity: 70.6%) might serve as a cutoff value for predicting the presence of cysts in medial cystic OLTs following BMS.

CONCLUSIONS

Medial cystic OLTs exhibited markedly lower sports levels, higher cyst presence rate, and inferior radiologic outcomes following BMS than lateral counterparts. Additionally, an OLT depth of 7.23 mm could be the cutoff value for predicting the presence of cysts regarding medial cystic OLTs after BMS.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Pathological progression of osteoarthritis: a perspective on subchondral bone

Osteoarthritis (OA) is a degenerative bone disease associated with aging. The rising global aging population has led to a surge in OA cases, thereby imposing a significant socioeconomic burden. Researchers have been keenly investigating the mechanisms underlying OA. Previous studies have suggested that the disease starts with synovial inflammation and hyperplasia, advancing toward cartilage degradation. Ultimately, subchondral-bone collapse, sclerosis, and osteophyte formation occur. This progression is deemed as "top to bottom." However, recent research is challenging this perspective by indicating that initial changes occur in subchondral bone, precipitating cartilage breakdown. In this review, we elucidate the epidemiology of OA and present an in-depth overview of the subchondral bone's physiological state, functions, and the varied pathological shifts during OA progression. We also introduce the role of multifunctional signal pathways (including osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL)/receptor activator of nuclear factor-kappa B (RANK), and chemokine (CXC motif) ligand 12 (CXCL12)/CXC motif chemokine receptor 4 (CXCR4)) in the pathology of subchondral bone and their role in the "bottom-up" progression of OA. Using vivid pattern maps and clinical images, this review highlights the crucial role of subchondral bone in driving OA progression, illuminating its interplay with the condition.

Research progress on the regulatory mechanism of integrin-mediated mechanical stress in cells involved in bone metabolism

Mechanical stress is an internal force between various parts of an object that resists external factors and effects that cause an object to deform, and mechanical stress is essential for various tissues that are constantly subjected to mechanical loads to function normally. Integrins are a class of transmembrane heterodimeric glycoprotein receptors that are important target proteins for the action of mechanical stress stimuli on cells and can convert extracellular physical and mechanical signals into intracellular bioelectrical signals, thereby regulating osteogenesis and osteolysis. Integrins play a bidirectional regulatory role in bone metabolism. In this paper, relevant literature published in recent years is reviewed and summarized. The characteristics of integrins and mechanical stress are introduced, as well as the mechanisms underlying responses of integrin to mechanical stress stimulation. The paper focuses on integrin-mediated mechanical stress in different cells involved in bone metabolism and its associated signalling mechanisms. The purpose of this review is to provide a theoretical basis for the application of integrin-mediated mechanical stress to the field of bone tissue repair and regeneration.

A new technique of autologous bone grafting for open-wedge high tibial osteotomy

Purpose

This study aimed to demonstrate the application of orthotopic bone flap transplantation with a fibula transplantation (OBFT-FT) in open-wedge high tibial osteotomy (OW-HTO) and to assess the effect of OBFT-FT on gap healing.

Patients and methods

From January to July 2020, 18 patients who underwent OW-HTO with OBFT-FT were reviewed for this study. Demographics, postoperative complications, and radiological and clinical outcomes of patients were collected. Finally, the clinical outcomes of patients were analyzed.

Results

A total of 14 patients were included in this study. The average age and body mass index were 59.6 ± 9.2 years and 28.1 ± 4.5 kg/m2, respectively. The average correction angle and gap width were 9.5 ± 1.8° and 10.2 ± 2.7 mm, respectively. The rates of radiological gap healing at sixth week, third month, and sixth month were 42.9%, 85.7%, and 100%, respectively. The mean Lysholm score, International Knee Documentation Committee score, and visual analog scale scores at sixth-month follow-up were significantly better than the preoperative scores (p < 0.001, p < 0.001, p = 0.001, respectively). And, no delayed union or non-union, collapse, loss of correction, or surgical site infection were found.

Conclusions

As a new technique for autologous bone graft, the OBFT-FT could be successfully applied in the treatment of gap healing after OW-HTO, and excellent radiological and clinical outcomes could be seen on patients' short-term follow-up.

Lateral meniscus with tears or with histologic calcification does not increase the risk of lateral osteoarthritis after medial unicompartmental arthroplasty

PURPOSE

Meniscal tears or histological meniscal calcifications (in the absence of radiological chondrocalcinosis) are frequent in osteoarthritis. Whether lateral meniscal lesions influence clinical outcomes after medial unicompartmental knee arthroplasty (UKA) is unknown.

METHODS

We analyzed 130 patients (130 knees) with medial unicompartmental knee arthroplasties between 2005 and 2015. These 130 knees had full articular cartilage thickness in the lateral compartment and no radiological chondrocalcinosis on preoperative radiographs. The lateral meniscus was analyzed with preoperative MRI and a biopsy of the anterior horn at the time of surgery. Synovial fluid was collected and analyzed for calcium pyrophosphate dihydrate crystal deposition (CPPD crystals). Lateral meniscal tears were untreated when detected on MRI or during surgery, with the hypothesis that these tears on the opposite compartment would remain asymptomatic in medial UKA. At average 10-year follow-up, patients were evaluated with clinical and radiographic outcome, with a focus on the risk of joint space narrowing of the lateral femorotibial compartment.

RESULTS

CPPD crystals were present in the synovial fluid of 70 knees. Lateral meniscal tears were seen on MRI in 34 (49%) normal meniscuses of the 60 knees without CPPD crystals and in six other knees without histological meniscal calcification despite CPPD crystals. Histological calcification was present on 61 lateral meniscuses with 53 meniscal tears. The results showed no significant differences in the clinical outcomes between knees with lateral meniscal tears or lateral meniscal histological chondrocalcinosis or both lesions and those without these conditions. Additionally, radiographic progression of osteoarthritis in the opposite femorotibial compartment of the knee was not more frequent in patients with these meniscal issues. The ten year cumulative survival rates, measured by the need for total knee arthroplasty, were 91% for knees without meniscal lesions and 92% for knees with these lesions.

CONCLUSION

On this basis, treatment of meniscal tears of the lateral compartment and routine aspiration of the knee to assess for birefringent crystals in the planning of medial UKA do not appear necessary.

Subchondral bone cysts remodel after correction of varus deformity in ankle arthritis

BACKGROUND

Subchondral bone cysts (SBCs) of the talus are frequently observed in ankle osteoarthritis (OA). It is unclear whether the cysts need direct treatment after correction of the varus deformity in ankle OA. The purpose of this study is to investigate the incidence of SBCs and the change after supramalleolar osteotomy (SMOT).

METHODS

Thirty-one patients treated by SMOT were retrospectively reviewed, and 11 ankles had cysts preoperatively. After SMOT without management of the cysts, the evolution of cysts was evaluated on weightbearing computerized tomography (WBCT). The American Orthopaedic Foot and Ankle Society (AOFAS) clinical ankle-hindfoot scale and a visual analog scale (VAS) were compared.

RESULTS

At baseline, the average cyst volume was 65.86 ± 60.53 mm3. The number and volume of cysts were reduced dramatically (P＜.05), and the cysts vanished in 6 ankles after the SMOT. The VAS and AOFAS scores improved significantly after SMOT (P＜.001), there was no significant difference between ankles with cysts and without cysts.

CONCLUSIONS

The SMOT alone without direct treatment of the SBCs led to a decrease in the number and volume of SBCs in varus ankle OA.

LEVEL OF EVIDENCE

Level IV, case series.

Subchondral Bone Cyst Development in Osteoarthritis: From Pathophysiology to Bone Microarchitecture Changes and Clinical Implementations

Osteoarthritis is a degenerative joint disease affecting middle-aged and elderly patients. It mainly involves weight-bearing joints such as the hip, knee and spine as well as the basilar joint of the thumb, causing dysfunction and painful symptoms. Often, joint arthritis is accompanied by cartilage defects, joint space narrowing, osteophytes, bone sclerosis and subchondral bone cysts (SBC). The aim of the present study was to explore the pathophysiology responsible for the development of SBCs as well as the association between SBCs and disease progress, the level of clinical symptoms and their impact on postoperative outcomes and risk of possible complications following joint replacements if left untreated. A literature review on PubMed articles was conducted to retrieve and evaluate all available evidence related to the main objective mentioned above. A few theories have been put forth to explain the formation process of SBCs. These involve MMPs secretion, angiogenesis, and enhanced bone turnover as a biological response to abnormal mechanical loads causing repeated injuries on cartilage and subchondral tissue during the development of arthritis. However, the application of novel therapeutics, celecoxib-coated microspheres, local administration of IGF-1 and activated chondrocytes following surgical debridement of SBCs hinders the expansion of SBCs and prevents the progression of osteoarthritis.

Alterations of the Subchondral Bone in Osteoarthritis: Complying with Wolff's law

Osteoarthritis (OA) is a whole joint disease that is significantly related to abnormal mechanical loads. Subchondral bone alterations, during the evolution course of OA, are considered as a reflection of adaptation of the bone tissue to mechanical loads. However, some of these alterations are taken as detriment and paradoxical. What are these structure, composition, and mechanical property alterations or mechanical functions for are not quite clear. In this review, we evaluate the possibility that these alterations are used for maintaining joint function. With taking excessive load as a risk factor and under conditions of articular cartilage gradually loss its thickness and its function of evenly distributing load on subchondral bone plate, and applying poroelasticity. Moreover, Boussinesq's pressure bulb theory and bone optimal design principles are utilized for bone mechanics. We found that each subchondral bone alteration has its unique mechanical function in resisting loads and maintaining joint function, and these alterations comply with both bone optimal design principles and Wolff's law within a proper range.

Osteotomies around the knee lead to corresponding frontal realignment of the ankle

Introduction

Despite the fact that osteotomies around the knee represent well-established treatment options for the redistribution of loads and forces within and around the knee joint, unforeseen effects of these osteotomies on the ankle are still to be better understood. It was therefore the aim of this study to determine the influence of osteotomies around the knee on the coronal alignment of the ankle. We hypothesize that osteotomies around the knee for correction of genu varum or valgum lead to a change of the ankle orientation in the frontal plane by valgisation or varisation.

Materials and methods

Long-leg standing radiographs of 154 consecutive patients undergoing valgisation or varisation osteotomy around the knee in 2017 were obtained and utilized for the purpose of this study. Postoperative radiographs were obtained after union at the osteotomy site. The hip knee ankle angle (HKA), the mechanical lateral distal femur angle (mLDFA), the mechanical medial proximal tibia angle (mMPTA) and five angles around the ankle were measured. Comparison between means was performed using the Wilcoxon-Mann–Whitney test.

Results

One hundred fifty-four patients (96 males, 58 females) underwent osteotomies around the knee for coronal realignment. The mean age was 51 ± 11 years. Correction osteotomies consisted of 73 HTO, 54 DFOs, and 27 double level osteotomies. Of all osteotomies, 118 were for valgisation and 36 for varisation. For valgisation osteotomies, the mean HKA changed from 5.8° ± 2.9° preoperatively to − 0.9° ± 2.5° postoperatively, whereas the mMPTA changed from 85.9° ± 2.7° to 90.7° ± 3.1° and the malleolar-horizontal-orientation-angle (MHA) changed from 16.4° ± 4.2° to 10.9° ± 4.2°. For varisation osteotomies, the mean HKA changed from − 4.3° ± 3.7° to 1.1° ± 2.2° postoperatively, whereas the mLDFA changed from 85.7° ± 2.2° to 89.3° ± 2.3° and the MHA changed from 8.8° ± 5.1° to 11.2° ± 3.2°.

Conclusion

Osteotomies around the knee for correction of coronal limb alignment not only lead to lateralization or medialization of the weight-bearing line at the knee but also lead to a coronal reorientation of the ankle. This can be measured at the ankle using the MHA. When planning an osteotomy around the knee for correction of genu varum or valgum, the ankle should also be appreciated—especially in patients with preexisting deformities, ligament instabilities, or joint degeneration around the ankle.

Cyst formation in the subchondral bone following cartilage repair

Subchondral bone cysts represent an early postoperative sign associated with many articular cartilage repair procedures. They may be defined as an abnormal cavity within the subchondral bone in close proximity of a treated cartilage defect with a possible communication to the joint cavity in the absence of osteoarthritis. Two synergistic mechanisms of subchondral cyst formation, the theory of internal upregulation of local proinflammatory factors, and the external hydraulic theory, are proposed to explain their occurrence. This review describes subchondral bone cysts in the context of articular cartilage repair to improve investigations of these pathological changes. It summarizes their epidemiology in both preclinical and clinical settings with a focus on individual cartilage repair procedures, examines an algorithm for subchondral bone analysis, elaborates on the underlying mechanism of subchondral cyst formation, and condenses the clinical implications and perspectives on subchondral bone cyst formation in cartilage repair.