Lingaraj Krishna
Email Address
doslk@nus.edu.sg
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Publication Body Mass Changes Across a Variety of Running Race Distances in the Tropics(2016) Tan, D.W; Yap, S.H; Wang, M; Fan, P.W; Teo, Y.S; Krishnasamy, P; Krishna, L; Hew-Butler, T; Lee, J.K.W; PHYSIOLOGY; ORTHOPAEDIC SURGERYBackground: Current literature evaluating body mass (BM) changes across a variety of running race distances is limited. The primary objective of this study was to profile the range of BM changes across race distances. The secondary objective was to evaluate the prevalence of exercise-associated hyponatremia (EAH) in runners admitted to the on-site medical tent following participation of race events of different distances. Methods: A total of 1934 runners across seven footrace categories (10-, 21-, 25-, 42-, 50-, 84-, and 100-km) were included in the study. One thousand eight hundred eighty-seven runners had their BM measured before and after each race. Blood sodium concentrations were measured from the remaining 47 symptomatic runners admitted to the on-site medical tents and did not complete the race. Results: In terms of hydration status, 106 (6 %) were overhydrated, 1377 (73 %) were euhydrated, and 404 (21 %) were dehydrated. All race distances exhibited similar percentage of overhydrated runners (5 % in 10 km, 3 % in 21 km, 5 % in 25 km, 6 % in 42 km, 8 % in 50 km, 7 % in 84 km, and 6 % in 100 km). Forty-seven runners were admitted to the medical tents. Eight (17 %) were diagnosed with EAH (4 from 42 km, 2 from 84 km, 2 from 100 km), 38 (81 %) were normonatremic, and 1 (2 %) was hypernatremic. The % ΔBM across all races ranged from −8.0 to 4.1 % with a greater decrement noted in the 42-, 50-, 84-, and 100-km categories. Conclusions: Approximately 3–8 % runners had increased post-race BM, suggesting overhydration regardless of race distance. Symptomatic EAH was seen at race distances at or above 42 km, where BM changes demonstrated the widest range of values. © 2016, The Author(s).Publication Complications and their risk factors following hip fracture surgery.(2013-08) Poh, K.S.; Lingaraj, K.; ORTHOPAEDIC SURGERYPURPOSE. To evaluate various postoperative complications and their risk factors in hip fracture patients. METHODS. 207 female and 87 male consecutive patients (mean age, 78.1 years) who underwent surgical (n=242) or conservative (n=52) treatment for closed fractures of the femoral neck (n=157) or peritrochanter (n=137) were prospectively studied. The types of complication and outcome were recorded. The comorbidity status of the patients was categorised based on the American Society of Anesthesiologists (ASA) classification. Complications and their associations with various risk factors and mortality were analysed. RESULTS. For all patients, the mean length of hospitalisation was 14.6 days. For the 242 patients who underwent surgical treatment after a mean of 3.6 days, 56.8% of them had at least one complication. Acute urinary retention (39.3%) and urinary tract infection (24.0%) were most common. Patients with ASA grade III or higher had 2.3 fold higher risk of developing complications than those with lower-grade comorbidity, whereas patients with delayed operation (>48 hours after presentation) had 1.8 fold higher risk of developing complications than those without delayed operation. Four patients died in hospital: 2 from myocardial infarction and 2 from upper gastrointestinal bleeding. CONCLUSION. Complications after hip fracture surgery were common. Advanced age, high ASA status, and delay in surgery were associated with higher complication rates. Operations should be performed on medically fit patients as early as possible.Publication Magnetic field therapy enhances muscle mitochondrial bioenergetics and attenuates systemic ceramide levels following ACL reconstruction: Southeast Asian randomized-controlled pilot trial(Elsevier BV, 2022-07-01) Stephenson, MC; Krishna, L; Pannir Selvan, RM; Tai, YK; Kit Wong, CJ; Yin, JN; Toh, SJ; Torta, F; Triebl, A; Frohlich, J; Beyer, C; Li, JZ; Tan, SS; Wong, CK; Chinnasamy, D; Pakkiri, LS; Lee Drum, C; Wenk, MR; Totman, JJ; Franco-Obregon, A; Dr Yee Kit Tai; DEAN'S OFFICE (MEDICINE); DIAGNOSTIC RADIOLOGY; MEDICINE; SURGERY; ORTHOPAEDIC SURGERY; BIOCHEMISTRYBackground: Metabolic disruption commonly follows Anterior Cruciate Ligament Reconstruction (ACLR) surgery. Brief exposure to low amplitude and frequency pulsed electromagnetic fields (PEMFs) has been shown to promote in vitro and in vivo murine myogeneses via the activation of a calcium–mitochondrial axis conferring systemic metabolic adaptations. This randomized-controlled pilot trial sought to detect local changes in muscle structure and function using MRI, and systemic changes in metabolism using plasma biomarker analyses resulting from ACLR, with or without accompanying PEMF therapy. Methods: 20 patients requiring ACLR were randomized into two groups either undergoing PEMF or sham exposure for 16 weeks following surgery. The operated thighs of 10 patients were exposed weekly to PEMFs (1 mT for 10 min) for 4 months following surgery. Another 10 patients were subjected to sham exposure and served as controls to allow assessment of the metabolic repercussions of ACLR and PEMF therapy. Blood samples were collected prior to surgery and at 16 weeks for plasma analyses. Magnetic resonance data were acquired at 1 and 16 weeks post-surgery using a Siemens 3T Tim Trio system. Phosphorus (31P) Magnetic Resonance Spectroscopy (MRS) was utilized to monitor changes in high-energy phosphate metabolism (inorganic phosphate (Pi), adenosine triphosphate (ATP) and phosphocreatine (PCr)) as well as markers of membrane synthesis and breakdown (phosphomonoesters (PME) and phosphodiester (PDE)). Quantitative Magnetization Transfer (qMT) imaging was used to elucidate changes in the underlying tissue structure, with T1-weighted and 2-point Dixon imaging used to calculate muscle volumes and muscle fat content. Results: Improvements in markers of high-energy phosphate metabolism including reductions in ΔPi/ATP, Pi/PCr and (Pi + PCr)/ATP, and membrane kinetics, including reductions in PDE/ATP were detected in the PEMF-treated cohort relative to the control cohort at study termination. These were associated with reductions in the plasma levels of certain ceramides and lysophosphatidylcholine species. The plasma levels of biomarkers predictive of muscle regeneration and degeneration, including osteopontin and TNNT1, respectively, were improved, whilst changes in follistatin failed to achieve statistical significance. Liquid chromatography with tandem mass spectrometry revealed reductions in small molecule biomarkers of metabolic disruption, including cysteine, homocysteine, and methionine in the PEMF-treated cohort relative to the control cohort at study termination. Differences in measurements of force, muscle and fat volumes did not achieve statistical significance between the cohorts after 16 weeks post-ACLR. Conclusion: The detected changes suggest improvements in systemic metabolism in the post-surgical PEMF-treated cohort that accords with previous preclinical murine studies. PEMF-based therapies may potentially serve as a manner to ameliorate post-surgery metabolic disruptions and warrant future examination in more adequately powered clinical trials. The Translational Potential of this Article: Some degree of physical immobilisation must inevitably follow orthopaedic surgical intervention. The clinical paradox of such a scenario is that the regenerative potential of the muscle mitochondrial pool is silenced. The unmet need was hence a manner to maintain mitochondrial activation when movement is restricted and without producing potentially damaging mechanical stress. PEMF-based therapies may satisfy the requirement of non-invasively activating the requisite mitochondrial respiration when mobility is restricted for improved metabolic and regenerative recovery.Publication Residual knee pain and functional outcome following total knee arthroplasty in osteoarthritic patients(2014) Nashi, N.; Hong, C.C.; Krishna, L.; ORTHOPAEDIC SURGERYPurpose: Total knee arthroplasty (TKA) is a successful and safe elective operation in managing patients with severe osteoarthritis of the knee. However, the presence of residual knee pain (RKP) post-TKA can adversely affect patient satisfaction and functional outcome. Hence, the aim of this paper is to identify the incidence, progression of knee pain, functional outcome post-TKA and possible predictive factors for the development of RKP post-TKA. Methods: A retrospective review of 357 patients was conducted with a minimum follow-up period of 2 years. Predictive factors reviewed include the patients' demographics, co-morbidities, type of implants and patellar management. For functional outcome, the patient's Knee Society Score (KSS) and Western Ontario and McMaster Universities Index of Osteoarthritis scores were analysed. To determine presence and severity of RKP, the sub-score for pain in the KSS was utilised. Results: In total, 31.1 and 28.9 % of the patients were found to have RKP at 1 and 2 years, respectively, though their functional outcome scores continued improving from 1 year. Ischaemic heart disease (IHD) patients were more likely to have RKP and poorer functional outcome at 1 year. Males and patients with posterior-stabilised implants were found to have better functional outcome at 1 and 2 years, respectively. Conclusions: Almost a third of the patients continued to have RKP at 2 years post-TKA, with factors such as gender, presence of IHD and implant type significantly associated with the development of RKP and/or poorer functional outcome scores. By recognising the incidence and predictive factors for RKP, physicians will be able to better manage their patients' expectations and optimise their pre-morbid status pre-operatively. Level of evidence: III. © 2014 Springer-Verlag Berlin Heidelberg.Publication The femoral sulcus in total knee arthroplasty: Reply to the letter by J.-Y. Jenny(2010-03) Lingaraj, K.; Bartlett, J.; ORTHOPAEDIC SURGERYPublication The ten-year pattern of hip diseases in Singapore.(2010-12) Singh, G.; Krishna, L.; Das De, S.; ORTHOPAEDIC SURGERYTo review patients with hip diseases undergoing total hip arthroplasty (THA) during 2 different periods. During the periods 1994 to 1996 and 2004 to 2006, 12 men and 28 women (mean age, 57 years) and 55 men and 78 women (mean age, 62 years) underwent THA for hip diseases, respectively. The aetiologies of the hip diseases were classified. Preand post-operative radiographs of the pelvis and hip were reviewed. The femoral head-tilt ratio (FHR) was measured. The number of patients undergoing THA increased 3-fold over 10 years; the proportion of different aetiologies was similar. Respectively, the most common aetiologies were acetabular dysplasia (33% vs. 40%) and avascular necrosis (33% vs. 42%). Only less than 5% of the patients had advanced osteoarthritis with no demonstrable cause, most of whom being Caucasians. The overall mean FHR was 1.07. There was no significant difference between male and female subjects. The pattern of hip diseases in Singapore remained similar over the 10-year interval, but the number of patients undergoing THA had increased 3-fold.Publication Polyethylene thickness in unicompartmental knee arthroplasty(2011-06) Lingaraj, K.; Morris, H.; Bartlett, J.; ORTHOPAEDIC SURGERYInadequate polyethylene thickness is a risk factor in the development of polyethylene wear in unicompartmental knee arthroplasty (UKA). The labelled thickness of polyethylene inserts often refers to the combined thickness of the insert and its metal backing. However specific information regarding the actual minimum thickness of the polyethylene is seldom available. We sought to determine the actual minimum thickness of polyethylene inserts used in five contemporary metal-backed UKA designs.The thinnest available insert from each of these designs was identified and measured at the lowest point of its concave articulating surface with a Kincrome electronic digital micrometer. The minimum thickness of the inserts ranged from 3.702. mm to 7.859. mm (mean values). In two of the inserts, the minimum thickness was found to be less than the recommended minimum thickness of 6. mm.Implant manufacturers should clearly indicate the actual minimum thickness of polyethylene inserts on their product labels. © 2010 Elsevier B.V.Publication Incidence of deep vein thrombosis following total hip arthroplasty: a Doppler ultrasonographic study.(2011-04) Wong, K.L.; Daguman, R.; Lim, K.H.; Shen, L.; Lingaraj, K.; ORTHOPAEDIC SURGERYTo investigate the incidence of deep vein thrombosis (DVT) following total hip arthroplasty (THA) in Singaporean patients. 197 patients (mean age, 60 years) underwent primary THA (n=155) or revision procedure (n=42) without receiving routine chemoprophylaxis. There were 149 Chinese, 25 Malays, 19 Indians, and 4 Eurasians. Duplex ultrasonography to detect DVT was performed on both lower limbs on postoperative day 5. 15 (8%) patients developed DVT, which was proximal in 6 and distal in 9. Only one patient had pulmonary embolism. The presence of DVT did not correlate to age, gender, race, presence of diabetes mellitus, history of malignancy, smoking habit, fixation type, primary versus revision type of surgery, or operating time. The incidence of DVT following THA in Singaporean patients is low, and routine chemoprophylaxis may not be indicated.Publication Chinese Ethnicity Is Associated With Concomitant Cartilage Injuries in Anterior Cruciate Ligament Tears(SAGE Publications Ltd, 2018) Chan, C.X.; Wong, K.L.; Toh, S.J.; Krishna, L.; SURGERY; ORTHOPAEDIC SURGERYBackground: Chinese ethnicity is associated with the presence of knee osteoarthritis. This raises the possibility that it may similarly be associated with concomitant meniscus and cartilage injuries in patients with anterior cruciate ligament (ACL) tears. There are currently no published data on the effect of Chinese ethnicity in this regard. Purpose: The primary aim was to determine whether Chinese ethnicity is associated with concomitant intra-articular injuries in patients with ACL tears and to verify the correlation of age, sex, body mass index, mechanism of injury, cause of injury, and presence of bone contusions on magnetic resonance imaging with such injuries. A secondary purpose was to determine the optimal time frame for surgical reconstruction in patients with identified risk factors for concomitant injuries. Study Design: Cohort study; Level of evidence, 3. Methods: The medical records of 696 patients from a multiethnic population who underwent ACL reconstruction from January 2013 to August 2016 were retrospectively analyzed. Univariate and multivariate logistic regression analyses were performed to identify patient factors that were associated with medial meniscus tears, lateral meniscus tears, and cartilage injuries. Further univariate analysis was conducted to determine the earliest time point for surgery, after which the rate of concomitant injuries was significantly higher. Results: Over half (69.1%, n = 481) of our study population sustained at least 1 other concomitant knee injury. Meniscus tears were most frequently associated with ACL tears (24.1% medial, 25.6% lateral, and 15.5% medial and lateral meniscus tears). Cartilage injuries were present in 18.4% of our cohort. Chinese ethnicity was associated with concomitant cartilage injuries. Increased age (?30 years) was significantly associated with cartilage injuries and male sex with medial and lateral meniscus tears. Among patients with these factors, significantly fewer medial meniscus tears and cartilage injuries were noted when surgery was carried out within 12 months of the index trauma. Conclusion: This is one of the first studies to have identified an association between Chinese ethnicity and concomitant cartilage injuries in ACL tears. This study also found an association between increased age and an increased prevalence of cartilage injuries. Male sex was associated with both medial and lateral meniscus tears. Definitive surgery should be performed within 12 months of the index injury to minimize further intra-articular injuries. � 2018, � The Author(s) 2018.Publication Femoral shaft fractures in the elderly - Role of prior bisphosphonate therapy(2011-07) Ng, Y.H.; Gino, P.D.; Lingaraj, K.; Das De, S.; ORTHOPAEDIC SURGERYIntroduction: There is a recent surge in interest on bisphosphonate related femoral fractures. Most studies have examined subtrochanteric fractures in patients on long-term bisphosphonates. This study evaluates the characteristics of low-impact femoral shaft fractures in elderly patients on long-term alendronate. Materials and methods: All patients above 60 years old admitted to the National University Hospital for femoral shaft fracture from January 2003 to January 2007 were retrospectively analysed. Of the 55 patients included, 7 had prior alendronate therapy and were examined in detail. Results: All 7 patients on prior alendronate therapy sustained their fractures by low-impact or atraumatic mechanisms of injury. 5 of these 7 patients exhibited a characteristic fracture pattern of thickened lateral cortices at the proximal fracture fragment (p < 0.05) and all 7 patients had either transverse or short oblique fractures. Notably, none of the 7 patients had bone mineral density scans prior to their fractures. One patient was started on alendronate after a vertebral compression fracture, whilst the other 6 patients were started on alendronate without any clear clinical indication. All 7 patients reported prodromal thigh pain 3 weeks to 2 years prior to the fracture. Conclusions: Low-impact femoral shaft fractures in elderly patients on long-term alendronate therapy represent a new entity of insufficiency fractures, with characteristic low-impact modes of injury and fracture patterns on radiograph. Prodromal thigh pain is a warning sign for impending fracture in this group of patients and should be evaluated closely. Teriparatide is a possible alternative to alendronate following such a fracture though more long-term clinical studies are required. © 2010 Elsevier Ltd. All rights reserved.