Chun Hoi Yan

Imaging biomarker with T1ρ and T2 mappings in osteoarthritis - in vivo human articular cartilage study.

INTRODUCTION Osteoarthritis (OA) of the knee is a common and disabling disease worldwide. Its prevalence is increasing in view of the aging population. Changes in collagen content, its orientation and GAG content in the articular cartilage with age are the major features in knee osteoarthritis. These changes in collagen and GAG contents show no manifestation in plain radiography and conventional magnetic resonance imaging (MRI). Nevertheless, early diagnosis of the knee osteoarthritis is of paramount importance clinically in view of the evolution of putative interventions in its early stage. The aim of this project is to identify the relationships between the two imaging biomarkers (i.e. T1ρ and T2 mappings) and the GAG concentration in living human symptomatic cartilage. METHODOLOGY 28 patients with clinical diagnosis of knee osteoarthritis were enrolled. 7 males and 16 females were recruited and their mean age was 68.1 (ranges from 53 to 84). Conventional PD sequence, T1ρ and T2 mappings were performed for each subject within 1 week before total knee arthroplasty. Articular cartilage from the lateral tibial plateau was harvested and the GAG content in cartilage was determined by using dimethylmethylene blue method. T1ρ mean and T2 values were calculated and correlate with GAG concentration statistically. RESULTS The mean value T1ρ was 40.3±13.5ms, ranging from 15.3 to 69.3ms and the mean value T2 was 31.0±10.5ms, ranging from 16.1 to 46.9ms. The mean value of GAG content was 80.1±33.3mg, ranging from 24.9 to 166.0mg while the mean value of GAG concentration was 267.4±165.9mg/cm(3), ranging from 91.3 to 760.5mg/cm(3). T2 values were inversely correlated with GAG concentration with R(2)=0.375, p=0.001 while T1ρ values were also inversely correlated with GAG concentration with R(2)=0.200, p=0.025. CONCLUSION This in vivo study confirmed that T1ρ and T2 values correlate with the GAG concentration in living human knee cartilages which corroborate with the previous works. The later (T2 values) is found more reliable in our study and less controversial in literatures. We postulate that T2 values can serve as a non-invasive imaging biomarker in the progress of knee osteoarthritis in terms of both disease diagnosis and treatment response monitoring.

Bilateral Knee Lipoma Arborescens: A Case Report:

A 45-year-old Chinese man presented with recurrent bilateral knee swelling and pain. He was initially diagnosed with gouty arthritis, but later found to have lipoma arborescens. Magnetic resonance imaging demonstrated frond-like proliferations of fatty synovium. Arthroscopic synovectomy was performed. Histological examination of the specimen revealed villiform fatty tissue covered by slightly thickened synovium characteristic of lipoma arborescens. Magnetic resonance imaging is useful in differentiating lipoma arborescens from other intra-articular lesions in patients with recurrent knee pain and swelling.

Review Article: Treatments for Bone Loss in Revision Total Knee Arthroplasty:

Bone deficiency hinders implant alignment and stabilisation of the bone-implant interface in revision total knee arthroplasty (TKA). Treatments for bone defects include bone cement, bone cement with screw reinforcement, metal augments, impaction bone grafts, structural allografts, and tantalum, depending on the location and size of the defects. Small defects are usually treated with cement, cement plus screws, or impaction allograft bone. Large defects are repaired with structural allografts or metal augments. Recent developments involve the use of highly porous osteo-conductive tantalum. We reviewed the pros and cons of each method for bone defect management in revision TKA.

Continuous Femoral Nerve Block versus Patient-Controlled Analgesia following Total Knee Arthroplasty:

Purpose. To compare total knee arthroplasty (TKA) patients who received continuous femoral nerve block (FNB) with local anaesthetics through a catheter versus patient-controlled analgesia (PCA) with intravenous morphine. Methods. 50 women and 10 men aged 51 to 84 years with matched characteristics underwent TKA and received either continuous FNB with local anaesthetics through a catheter (n=30) or PCA with intravenous morphine (n=30). None of the patients had had previous knee surgery. All operations were performed according to the standard protocol. Daily mean pain numerical rating scale at rest (NRS-R) and during movement (NRS-M), requirement of extra pain control, complications related to pain control, and overall patient satisfaction in both groups were compared. Results. Both groups were similar in terms of pain NRS-R and NRS-M, overall satisfaction, and length of hospital stay. Within each group, pain NRS-M score was significantly higher than pain NRS-R score. In the FNB group, 3 patients had dislodgement of the femoral catheter on day 1 and switched to PCA with intravenous morphine. Two of them had fair satisfaction. Patients in the PCA group had significantly more side-effects (nausea, vomiting, dizziness, and pruritis); 2 of the 5 patients with nausea and vomiting had fair satisfaction. No patients had any surgical complication. Conclusion. Both FNC and PCA provide reliable pain control.

Anterior dislocation of Insall Burstein II total knee arthroplasty secondary to polyethylene tibial post fracture: a case report.

Anterior dislocation of a posterior stabilised total knee arthroplasty secondary to a polyethylene tibial post fracture is rare. We report one such case in an 89-year-old Chinese woman who had undergone total knee arthroplasty using the Insall Burstein II prosthesis 7 years earlier. The failure was due to sagittal malalignment of the components. Owing to more pronounced anterior bowing of the distal femoral shaft in southern Chinese, neutral component placement is often biased toward hyperextension. When the knee reaches full extension, anterior impingement occurs. Surgeons must therefore take extra care in preoperative planning and bone cutting in this population.

Inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside’s line

Purpose. To assess inter- and intra-observer errors in identifying the transepicondylar axis and Whitesides line in a cadaveric model mimicking total knee arthroplasty. Methods. Four cadaveric knees with intact soft tissues were used. The knees were exposed anteriorly using the Insall approach, with the patella everted laterally. Three observers (2 surgeons and one trainee) took turns to identify the anatomic landmarks of the transepicondylar axis and Whitesides line. Each observer repeated the process 20 times. Each identification was photographed and referenced with the true values obtained from the knees after they were stripped of all soft tissue. Inter- and intra-observer errors in the anatomic landmarks were compared. Results. Inter-observer error was significant with both the transepicondylar axis and Whitesides line (p<0.001, one-way ANOVA). The intra-observer variation was greater for Whitesides line than the transepicondylar axis (standard deviation, 4.2° vs 2.5°). The maximum potential errors in the transepicondylar axis and Whitesides line were 13° and 24°, respectively. Conclusion. The accuracy of rotational alignment of the transepicondylar axis and Whitesides line were operator-dependent, and their intra-operative reproducibility was low.

Revision total hip arthroplasty with femoral impaction bone grafting

Purpose. To report the radiological and clinical results of revision total hip arthroplasty (THA) with femoral impaction bone grafting (IBG). Methods. 4 men and 9 women (15 hips) aged 38 to 84 years underwent revision THA with femoral IBG using Elite plus stems for aseptic loosening or infection. Results. The mean follow-up duration was 7.7 years. The Harris hip score improved from 61.7 to 83.7. There was no pain in 11 hips and slight pain in 4. The mean subsidence was 5.7 mm. The mean change of alignment was 1.2°. There was no radiological evidence of stem loosening. One stem was revised due to a peri-prosthetic fracture. Cortical healing was noted in 11 hips, and trabecular incorporation in 10. Conclusion. Although intra- and post-operative complications were not uncommon, femoral IBG is a safe procedure in carefully selected patients and offers good medium-term results.

The use of three-dimensional printing technology in orthopaedic surgery: A review

Three-dimensional (3-D) printing or additive manufacturing, an advanced technology that 3-D physical models are created, has been wildly applied in medical industries, including cardiothoracic surgery, cranio-maxillo-facial surgery and orthopaedic surgery. The physical models made by 3-D printing technology give surgeons a realistic impression of complex structures, allowing surgical planning and simulation before operations. In orthopaedic surgery, this technique is mainly applied in surgical planning especially revision and reconstructive surgeries, making patient-specific instruments or implants, and bone tissue engineering. This article reviews this technology and its application in orthopaedic surgery.

Review Article: Osteophytes

An osteophyte is a fibrocartilage-capped bony outgrowth that is one of the features of osteoarthritis. This study reviewed the types, risk factors, pathophysiology, clinical presentations, and medical and surgical treatment of osteophytes. Extraspinal osteophytes are classified as marginal, central, periosteal, or capsular, whereas vertebral osteophytes are classified as traction or claw. Risk factors for development of osteophytes include age, body mass index, physical activity, and other genetic and environmental factors. Transforming growth factor β plays a role in the pathophysiology of osteophyte formation. Osteophytes can cause pain, limit range of motion, affect quality of life, and cause multiple symptoms at the spine. Medical treatment involves the use of bisphosphonates and other non-steroidal anti-inflammatory agents. Surgical treatment in the form of cheilectomy for impingement syndromes during joint replacement is recommended.

Abnormal subchondral bone remodeling and its association with articular cartilage degradation in knees of type 2 diabetes patients

Type 2 diabetes (T2D) is associated with systemic abnormal bone remodeling and bone loss. Meanwhile, abnormal subchondral bone remodeling induces cartilage degradation, resulting in osteoarthritis (OA). Accordingly, we investigated alterations in subchondral bone remodeling, microstructure and strength in knees from T2D patients and their association with cartilage degradation. Tibial plateaus were collected from knee OA patients undergoing total knee arthroplasty and divided into non-diabetic (n=70) and diabetes (n=51) groups. Tibial plateaus were also collected from cadaver donors (n=20) and used as controls. Subchondral bone microstructure was assessed using micro-computed tomography. Bone strength was evaluated by micro-finite-element analysis. Cartilage degradation was estimated using histology. The expression of tartrate-resistant acidic phosphatase (TRAP), osterix, and osteocalcin were calculated using immunohistochemistry. Osteoarthritis Research Society International (OARSI) scores of lateral tibial plateau did not differ between non-diabetic and diabetes groups, while higher OARSI scores on medial side were detected in diabetes group. Lower bone volume fraction and trabecular number and higher structure model index were found on both sides in diabetes group. These microstructural alterations translated into lower elastic modulus in diabetes group. Moreover, diabetes group had a larger number of TRAP+ osteoclasts and lower number of Osterix+ osteoprogenitors and Osteocalcin+ osteoblasts. T2D knees are characterized by abnormal subchondral bone remodeling and microstructural and mechanical impairments, which were associated with exacerbated cartilage degradation. In regions with intact cartilage the underlying bone still had abnormal remodeling in diabetes group, suggesting that abnormal bone remodeling may contribute to the early pathogenesis of T2D-associated knee OA.