Short-term primary and revision modular dual-mobility cup total hip arthroplasty outcomes in high-risk dislocation patients: a retrospective study.

PURPOSE: Modular dual-mobility cups (MDMCs) have a lower risk for dislocation after total hip arthroplasty (THA). The primary aims of our study were to analyze implant survivorship and to determine complications, especially dislocation, and revision rates of primary THAs used for hip fracture patients and for revision THAs. Secondary aims were to evaluate mortality after MDMC surgery and to find out if introduction of MDMC at our institution (Kuopio University Hospital, Finland) have decreased dislocation rate. METHODS: This retrospective cohort study consisted of 101 MDMC patients who were consecutively operated at our institution between April 1, 2018 and June 30, 2020. The implant survival rate, complications and mortality were evaluated with minimum of 2-year follow-up. Finnish Hospital Discharge Register was used to find out yearly dislocation rates following THA at our institution. RESULTS: The cumulative estimate implant survival after MDMC in the primary THA group was 97% at 2 years, and in the revision THA group, it was 90% at 2 years. Dislocation was a rare complication in the primary THA group (1.4%), while it was common in revision THA group (12.9%). The cumulative estimate for mortality after MDMC in the primary THA group was 13% at 2 years, and in the revision group, it was also 13% at 2 years. The yearly number of patients who had re-hospitalization period due to THA dislocation decreased 46% after implementation of MDMC. CONCLUSION: Short-term survival and complication rates after MDMC were excellent after primary THA and moderate after revision THA. Implementation of MDMC THA for hip fracture patients seems to have effectively decrease dislocation rate during a short follow-up.

Long-term survival analysis of cementless large-diameter head metal-on-metal total hip arthroplasty.

INTRODUCTION: The aim of this retrospective study was to study the long-term survival and reasons for revisions of a single-type, large-diameter head (LDH) metal-on-metal (MoM) implant. A special study interest was to find the threshold level for revision in terms of adverse reaction to metal debris (ARMD). MATERIALS AND METHODS: In this cohort study, we retrospectively reviewed 234 patients (253 hips) who received 38 mm head size LDH MoM total hip arthroplasties (THAs) between 01 January 2004 and 31 December 2009 at our institution. Patient symptoms, conventional radiographs, magnetic resonance imaging (MRI) findings and whole blood metal ions were studied. RESULTS: The median follow-up time was 11.5 years. The Kaplan-Meier cumulative survival estimate of the implant was 89.6% at 10 years and 82.9% at 14.6 years. Overall, 34/253 (13.4%) hips were revised during the follow-up period and of these; 19/34 (55.9%) were revised due to ARMD. The prevalence of ARMD was 12.4% (29/234 patients). CONCLUSIONS: The survival of the implant was on a moderate level as the 10-year cumulative survival rate was 89.6%. The exact threshold level for ARMD revision cannot be determined due to multiple variables affecting factors in re-operation decision-making.

Long-term follow-up results of medial opening wedge high tibia osteotomy with a pre-countered non-locking steel plate.

INTRODUCTION: This retrospective study investigated the long-term follow-up results of medial opening wedge high tibial osteotomy (MOWHTO) with a pre-countered non-locking steel plate implant (Puddu plate = PP) used for medial knee osteoarthrosis (OA) treatment. MATERIALS AND METHODS: Consecutive 70 MOWHTOs (66 patients) were performed between 01.01.2004 and 31.12.2008 with the mean follow-up time of 11.4 (SD 4.5; range 1.2-16.1) years. The Kaplan-Meier survival analysis was used to evaluate the cumulative survival of the implant in terms of age (< 50 years old and ≥ 50 years old) and gender. Adverse events were studied and Cox regression analysis was used to evaluate risk factors [age, gender, body mass index (BMI), preoperative mechanical axis, severity of OA, use of bone grafting or substitution and undercorrection of mechanical axis from varus to valgus] for revisions. RESULTS: The estimates for the cumulative survival with no need for TKA after MOWHTO were 86% at 5 years, 67% at 10 years and 58% at 16.1 years (SE 0.6, CI 95% 11.1-13.5). A total of 33/70 (47%) adverse events occurred and 38/70 (54%) knees required some revision surgery during the follow-up. Cox regression did not show any statistically significant risk factors for revision. CONCLUSIONS: The PP has feasible MOWHTO results with a cumulative survival of 67% at 10 years with no need for conversion to TKA. Many adverse events occurred and revision rate due to any reason was high. Age or gender did not have statistically significant differences in terms of survival.

Lumbar instrumented posterolateral fusion in spondylolisthetic and failed back patients: a long-term follow-up study spanning 11-13 years.

UNLABELLED: INTRODUCTION AND MATERIALS: We examined lumbar transpedicular instrumented posterolateral fusion patients operated on between 1992 and 1997 presenting: degenerative spondylolisthesis with spinal stenosis; adult isthmic spondylolisthesis; failed back syndrome after one to five discectomies; and failed back syndrome after one to three laminectomy operations (groups 1-4, respectively). METHODS: They were examined by an independent orthopedic surgeon, completed the Oswestry Disability Index (ODI) and visual analog scale (VAS) questionnaires and their outcome was evaluated. RESULTS: The overall patient satisfaction at follow-up (mean 11.7 years) was 82.1%. The reoperation rate was 15.1% (7.5% due to adjacent segment disease). CONCLUSION: Group 1 showed the greatest improvements in ODI and VAS values, Group 2 the lowest and Group 3 the highest preoperative values, and Group 4 the second highest improvements. Patient satisfaction scores were 90.3, 69.7, 63.6 and 80.0%, respectively, and unplanned reoperation rates were 6.5, 9.1, 31.8 and 20.0%. Thus, long-term outcomes of lumbar instrumented posterolateral fusion (rarely previously studied) were satisfactory for >80% of patients, but varied among groups.

Survival and failure analysis of 167 medial opening wedge high tibial osteotomy with a locking titanium plate.

INTRODUCTION: This retrospective study investigated the survival rate and complications of medial opening wedge high tibial osteotomy (MOWHTO) with a precountered titanium locking plate. HYPOTHESIS: Advanced age (≥50years), gender, body mass index (BMI), type of osteotomy cut (monoplanar or biplanar), osteoarthritis (OA) grade, the use of bone grafting or substitution and preoperative hip-knee-ankle (HKA) have impact on MOWHTO survival. MATERIAL AND METHODS: A total of 167 knees (155 patients) were consecutively operated during the study period of 01.01.2006-31.12.2014. The primary outcome measure was survival without a need for revision to total knee arthroplasty (TKA). The secondary outcome was a major adverse event leading to revision surgery. Adverse events and complications were evaluated and radiological analyses were done. Furthermore, risk factors that affected the survival were analysed with the Cox regression model. RESULTS: The mean follow-up time was 7.7 (SD: 2.7, range: 0.9-14.5) years. The Kaplan-Meier estimates for the cumulative survival considering no need for TKA after MOWHTO was 90% at 5years, 78% at 10years and 61% at 14.5years (SE: 0.4, 95% CI: 11.2-12.9). The adverse event rate was 30% and 35% of the patients required a secondary surgery. The Cox regression model did not show that age, gender, weight, osteotomy type, the use of bone grafting or substitution, preoperative HKA angle or OA grade were not risk factors for conversion to arthroplasty. DISCUSSION: MOWHTO with locking plate provides good survival with no need for TKA in 78% of the knee medial OA patients at 10years of cumulative follow-up. However, a high adverse event rate (30%) is expected. Risk factors for conversion to TKA were not found and thereby hypothesis of this study was not proved. LEVEL OF EVIDENCE: VI; Retrospective cohort study.

Midterm follow-up results of two different types of implants in opening wedge high tibia osteotomy.

BACKGROUND: This retrospective study investigated the midterm results of medial opening wedge high tibia osteotomy, with a monoplanar or a biplanar osteotomy using two types of implant system. METHODS: Osteotomies were performed on 241 knees (231 patients). The mean follow-up period was 6.0 years (SD 3.0, range 0.2-12.8 years). Two types of implant system were used, a precountered non-locking plate (PP) (n = 74) and a precountered locking plate (LP) (n = 167). A Kaplan-Meier cumulative survival curve and a Cox regression model were used to analyse and revise survival and risk factors. RESULTS: Cumulative survival estimates for LP were 80% at 5 years, and 64% at 10 years (SE = 0.4, CI 95%: 9.0-10.5), and for PP, they were 68% at 5 years and 49% at 10 years (SE = 0.5, CI: 95% 6.3-8.2) (p = 0.024). The revision rate was 26% (44/167) for the LP group, and 47% (35/74) for the PP group (p = 0.001). Reoperations on LP osteotomies occurred for the tibial monoplanar cut and biplanar cut groups, in 19/52 (37%) and 25/167 (16%) osteotomies, respectively (p = 0.04). Our Cox regression model showed that PP had a higher risks (RR = 1.7; CI: 95% 1.1-2.6) of revision, when compared with LP (p = 0.026). CONCLUSIONS: The risk of revision for any reason and that of early conversion to total knee arthroplasty (TKA) after high tibia osteotomy were significantly increased for PP, when compared with LP.

Revision hip arthroplasty using a porous tantalum acetabular component.

INTRODUCTION: Reconstruction of acetabulum in case of bone defects can be challenging. The aim of this retrospective study was to investigate the 10-year survival of trabecular tantalum metal (TM) acetabulum component in revision hip arthroplasty operations and to evaluate complications. METHODS: A total of 100 consecutive acetabulum revision hip arthroplasties (100 patients) were operated on between May 2004 and October 2006 at Kuopio University Hospital. The mean follow-up time was 9.4 years and the median was 11.5 years (SD 4.118; range 0.1-13.4 years). Kaplan-Meier survival analysis was performed to study the survival of patients to re-revision surgery. Intra- and postoperative complications and reasons for re-revision were evaluated. RESULTS: The Kaplan-Meier analysis showed a cumulative proportion of revision hip survivorship of 66% at 13.4 years (SE 0.403, 95% CI, 10.886-12.466) based on the need for further re-revision surgery for any major reason. The Kaplan-Meier survival analysis of time to re-revision surgery due acetabular component loosening showed a cumulative proportion of survivorship of 98.9% at 13.4 years (SE 0.136; 95% CI, 12.998-13.529). There were a total of 41/100 complications and the most common complication was dislocation (24/100). Re-revision for any major reason was performed on 18/100 of the revision arthroplasties. The mean time to re-revision was 4.9 years (SD 5.247; range 0.1-13.2 years). DISCUSSION: The trabecular TM acetabular component gives excellent outcomes regarding stability and fixation to the acetabulum in acetabulum revision hip arthroplasty at a minimum of ten years of follow-up. However, acetabular component malposition and the small head size (28 mm) are risk factors for dislocation.

Health-Related Quality of Life after Hip and Knee Arthroplasty Operations.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the health-related quality of life before and after a hip and a knee arthroplasty operation using a 15D instrument and to compare these scores to the Finnish control population 15D scores. METHODS: The pre- and post-operative data of 15D were prospective collected from the patients undergoing total hip arthroplasty or total knee arthroplasty at the Kuopio University Hospital. Post-operative data were collected at 6 and 12 months after the operation. RESULTS: The mean change of the 15D score after hip arthroplasty was +0.062 and after knee arthroplasty, it was +0.033 at the 12-month follow-up (p < 0.001). Total hip arthroplasty patients of all ages reached the control population 15D scores at the 12-month follow-up. Of the total knee arthroplasty patients, only patients aged >75 years and males aged 55-64 years did reach control population 15D scores at the 12-month follow-up. Patients experienced a statistically significant improvement in mobility, vision, sleeping, usual activities, discomfort and symptoms, distress, and vitality (p < 0.05). CONCLUSIONS: Successful hip and knee arthroplasty operations improve patients' health-related quality of life. According to this study, hip arthroplasty improves the health-related quality of life more than knee arthroplasty.

The clinical outcome of revision knee replacement after unicompartmental knee arthroplasty versus primary total knee arthroplasty: 8-17 years follow-up study of 49 patients.

When unicompartmental knee arthroplasty (UKA) failure occurs, a revision procedure to total knee arthroplasty (TKA) is often necessary. We compared the long-term results of this procedure to primary TKA and evaluated whether they are clinically comparable. Twenty-one patients underwent UKA conversion to TKA between 1991 and 2000. The results of these patients were compared to the group of 28 primary TKA patients with the same age, sex and operation time point. The long-term outcomes were evaluated using clinical and radiological analysis. The mean follow-up period of the patients was 10.5 years. The UKA revision patients were more dissatisfied, as measured by the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scale (0-100 mm) compared to the primary TKA patients (pain 18.1/7.8; p = 0.014; stiffness 25.7/14.4, p = 0.024; physical function 19.0/14.8, p = 0.62). Two patients were revised twice in the UKA revision group. There was one revision in the primary TKA group (p = 0.39). Improvement in range of motion (ROM) was better in the TKA patients compared to the UKA revision patients (8.2 degrees /-2.6 degrees , p = 0.0001). We suggest that UKA conversion to TKA is associated with poorer clinical outcome as compared to primary TKA.

Bone mineral density and single photon emission computed tomography changes after total knee arthroplasty: a 2-year follow-up study.

Dual X-ray absorptionmetry (DXA) provides a highly reproducible method for quantitative analysis and monitoring periprosthetic bone mineral density (BMD) after total knee arthroplasty (TKA). Single photon emission computed tomography (SPECT) with bone avid radiopharmaceuticals reflects bone metabolic activity and circulation. We combined information from DXA and SPECT to assess the evaluation of the dynamic balance between BMD and bone turnover. Sixteen patients underwent serial DXA (Lunar Expert XL) and 99mTc-methylene diphosphonate SPECT measurements until 2 years after TKA. A rapid bone loss, up to 25.5%, was detected in femur during the first six postoperative months. However, tibial periprosthetic BMD remained close to baseline. There was a significant correlation between 12-month SPECT uptake and preceding BMD change in medial tibia (r = 0.5, P = 0.044). At 12 months, SPECT uptakes in the operated knee were notably higher compared with those of the control knee. SPECT uptakes showed statistically significant decreases from 12 months to 24 months, while SPECT uptake in the control knee remained stable. In tibia, the results are more complex; referring that increased bone remodelling is continuing below the tibial tray. Furthermore, femoral diaphyseal uptake remained elevated, while corresponding tibial uptake had levelled off at 2 years. Increased SPECT uptake during the first 2 years after uncomplicated TKA results most likely from normal postoperative bone remodelling. Levelling of SPECT uptake may indicate a new balance between bone loss and regain.

The Cerebrospinal Fluid Distribution of Postoperatively Administred Dexketoprofen and Etoricoxib and Their Effect on Pain and Inflammatory Markers in Patients Undergoing Hip Arthroplasty.

BACKGROUND AND OBJECTIVE: Based on earlier literature, etoricoxib may have a delayed analgesic effect in postoperative setting when analgesic efficacy of nonselective nonsteroidal anti-inflammatory drug dexketoprofen is rapid. This may be caused by slow penetration of etoricoxib into the central nervous system (CNS). Therefore we decided to determine the plasma and cerebrospinal fluid (CSF) pharmacokinetics and pharmacodynamics of dexketoprofen and etoricoxib in patients with hip arthroplasty. METHODS: A total of 24 patients, scheduled for an elective primary hip arthroplasty were enrolled. After surgery, 12 subjects were randomized to received a single intravenous dose of dexketoprofen, and 12 subjects were given oral etoricoxib. Paired blood and CSF samples were taken up to 24 h for measurement of drug concentrations, interleukin (IL)-6, IL-1ra and blood for interleukin 10. RESULTS: In CSF the highest measured concentration (C max) of dexketoprofen was 4.0 (median) ng/mL (minimum-maximum 1.9-13.9) and time to the highest concentration (t max) 3 h (2-5), and for etoricoxib C max 73 ng/mL (36-127) and t max 5 h (1-24), respectively. Opioid consumption during the first 24 postoperative hours was similar in the two groups. Dexketoprofen and etoricoxib had a similar effect on the postoperative inflammatory response. No significant differences considering pain relief or adverse events were found between the two groups. CONCLUSION: Dexketoprofen and etoricoxib entered the CNS readily, already at 30 min after administration dexketoprofen was detected in the CSF in most subjects and etoricoxib after 60 min. A single dose of dexketoprofen and etoricoxib provided a similar anti-inflammatory and analgesic response after major orthopaedic surgery.

Bone mineral density in the proximal femur and contralateral knee after total knee arthroplasty.

Osteoarthrosis (OA) is often associated with pain and disability, which are relieved after total knee arthroplasty (TKA), but the nature of bone changes associated with OA is controversial. We examined preoperative hip and contralateral knee bone mineral density (BMD) in patients requiring TKA and monitored the BMD changes postoperatively. Sixty-nine patients, scheduled to have TKA for osteoarthrotic knees, had both hips and contralateral knee BMD measured by dual-energy X-ray absorptiometry (DXA) at the time of operation (baseline) and at 1 yr after operation. X-rays of the knee joints were also taken to evaluate the severity of OA. Preoperatively, 27% and 38% of the patients had total hip BMD Z-score more than 1 SD in the operated side and contralateral hips, respectively. In all regions of interest (ROI), the mean baseline BMD of the affected side proximal femur was significantly lower than that of the contralateral side (p < 0.0005-0.019). The severity of OA was not associated with BMD. During 1-yr follow-up, the postoperative knee status and the physical activity of the patients (AKS score) improved. However, neither the hip nor the nonoperated knee BMDs increased. Knee OA is associated with significantly lower BMD values in the affected side compared with the contralateral hip, and these levels remained similar or decreased during a 1-yr follow-up. We conclude that improved mobility after TKA does not improve the effects of preoperative disuse-associated bone loss in the short term.

Periprosthetic femoral bone loss after total knee arthroplasty: 1-year follow-up study of 69 patients.

The clinical survival of joint arthroplasties is related to the quality of the surrounding bone environment. Bone mineral density (BMD) is an important measure of bone strength and quality. The aim of this prospective study was to measure the quantitative changes in BMD in the distal femur after cemented total knee arthroplasty (TKA) in osteoarthrotic knee joints. Sixty-nine patients with TKA were scanned postoperatively using dual-energy X-ray absorptiometry (DXA) within a week of surgery, and at 3-, 6-, and 12-month follow-ups. An average decrease in bone density of 17.1% (mean range of 12.1-22.8%) was measured adjacent to the prosthesis at the 12-month follow-up (repeated measures ANOVA P<0.0005). Bone loss was most rapid during the first 3 months after TKA. The clinical status and function parameters of the knee joint, evaluated by the American Knee Society (AKS) score, had improved significantly on the preoperative values at the three- and 12-month follow-ups (P<0.0005). However, improvement in the AKS score was not associated with periprosthetic BMD change (P=0.204), whereas age (P=0.067) and body mass index (P=0.019) correlated with BMD loss for the total metaphyseal region of interest (ROI), by repeated measures ANOVA. We suggest that the observed periprosthetic bone loss was mainly the result of prosthesis-related stress-shielding.

Changes in bone mineral density of the distal femur after total knee arthroplasty: a 7-year DEXA follow-up comparing results between obese and nonobese patients.

BACKGROUND AND PURPOSE: Periprosthetic femoral bone mineral density (BMD, g/cm2) decreases after total knee arthroplasty (TKA) as a result of the stress-shielding phenomenon. It is not known whether obesity has an effect on this phenomenon or not. The aim of this study was to assess long-term periprosthetic BMD changes after TKA and compare whether there is a difference between obese and nonobese patients. METHODS: A total of 69 TKAs in 61 patients were performed, and BMD measurements of the distal femur were followed up to 7 years postoperatively. The patients were divided into two study groups according to their body mass index, and the groups were compared in relation to BMD and functional outcome. RESULTS: The mean of periprosthetic bone loss during the 7-year follow-up varied from 10.3% to 30.6% depending on the region of interest (p<0.0005). The highest bone-loss rates were detected during the first three postoperative months. A total of 26 patients were categorized as obese with a body mass index value of ≥30 kg/m2. The obese patients' total periprosthetic BMD was higher at both baseline (8.6%) and 7 years after operation (p=0.05) (15.2%). CONCLUSION: Periprosthetic bone loss around the femoral component continued for up to 7 years postoperatively. The loss of bone density was not associated with any negative clinical outcome in this study, but periprosthetic bone loss was of a smaller quantity in the obese which is probably due to higher weight induced stresses on bone.

Periprosthetic bone mineral density changes after unicondylar knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) has received renewed interest in the last decade. UKA involves minor injury to soft tissues, limited removal of bone and delicate preservation of knee anatomy and geometry. In theory, UKA provides an opportunity to restore post-surgical knee kinematics to near normal. HYPOTHESIS: UKA leaves patellofemoral joint free to meet high mechanical forces with no stress-shielding and therefore might preserve bone mineral density (BMD). PATIENTS AND METHODS: We studied 21 patients with osteoarthritis (OA), who had received medial compartment UKA at Kuopio University Hospital between October 1997 and September 2000. BMD was measured by dual-energy X-ray absorptiometry (DEXA), at baseline (within a week after surgery) and at intervals until 7 years. RESULTS: DEXA results were reproducible. The highest rate of periprosthetic bone loss occurred during the first 3 months after UKA. The average loss in BMD was 4.4% (p = 0.039) in the femoral diaphysis and it ranged from 11.2% (p < 0.001) to 11.9% (p = 0.002) in the distal femoral metaphysis; however, BMD changes in these regions, from 2 years to 7 years, were nonsignificant. At the 1-year follow-up, the BMD of the medial tibial metaphysis had increased by 8.9% (p = 0.02), whereas those in the lateral tibial metaphysial (-2.4%) and diaphysial regions (-2.0%) did not change significantly. INTERPRETATIONS: UKA did not preserve periprosthetic BMD in the distal femoral metaphysis, whereas BMD changes in the tibial metaphysis were minor, consistent with a mechanical balance between the medial and lateral tibial compartments. LEVEL OF EVIDENCE 2B: Prospective case control study.

Perioperative chronic use of statins and the risk of muscle complaints in patients undergoing knee and hip endoprosthesis surgery.

STUDY OBJECTIVE: To assess whether regular statin therapy enhances muscular and hepatic deterioration and muscle complaints in patients undergoing elective arthroplasty. DESIGN: Prospective, case-controlled, observational study. SETTING: Tertiary-level university teaching hospital in Eastern Finland. PATIENTS: 48 ASA physical status I, II, and III patients, aged 51 to 84 years, 24 of whom were scheduled for hip arthroplasty (12 pts with and 12 without statin therapy) and 24 patients who were to undergo knee arthroplasty (12 pts with and 12 without statin therapy). INTERVENTIONS: Before and after surgery, all patients were interviewed for muscular and hepatic symptoms and signs. MAIN MEASUREMENTS: S-creatine kinase, S-alanine aminotransferase, P-creatinine, S-lactate dehydrogenase, P-potassium, S-myoglobin, and U-myoglobin were measured at baseline and at 6, 24, and 72 hours after surgery. MAIN RESULTS: S-creatine kinase and S-myoglobin increased in all study groups at 6 hours after surgery and remained elevated for 72 hours, with no differences noted in patients treated with or without statins. There was no increase in the amount of muscular or hepatic complaints after surgery. CONCLUSION: Long-term statin therapy does not appear to increase the risk of muscular adverse effects in patients receiving major endoprosthesis surgery.

Periprosthetic bone loss after cemented total hip arthroplasty: a prospective 5-year dual energy radiographic absorptiometry study of 15 patients.

In this prospective 5-year study, we determined the periprosthetic bone loss after cemented total hip arthroplasty (THA) in 15 patients using dual energy X-ray absorptiometry (DXA). A reduction in the periprosthetic bone mineral density (BMD) of 5-18% occurred in all Gruen regions, or regions of interest (ROI), during the first 3 months after THA. The bone loss continued up to 6 months in almost all ROIs. From 1 to 5 years, we found only minor changes in BMD in periprosthetic bone. After the follow-up, the mean greatest bone loss (26%) was seen in the femoral calcar area. The reduction in mean BMD was 5% in men, and 16% in women. The lower the preoperative BMD, the higher was the postoperative bone loss. We found that after the phase of acute bone loss, further loss was minimal, reflecting merely the normal ageing of bone after uncomplicated THA.

Periprosthetic tibial bone mineral density changes after total knee arthroplasty: one-year follow-up study of 69 patients.

BACKGROUND: The critical structure supporting the prosthetic components in total knee arthroplasty (TKA) is tibial trabecular bone. The quality of tibial bone can be evaluated by bone mineral density (BMD) measurements. PATIENTS AND METHODS: We prospectively measured changes in BMD in the proximal tibia after cemented TKA in osteoarthrotic knees. 69 patients were scanned by dual-energy X-ray absorptiometry (DXA) within a week after surgery, and after 3, 6 and 12 months. RESULTS: At baseline, the medial region of interest (ROI) BMD was higher in the varus knees than in the valgus aligned knees (p=0.02). The medial metaphyseal ROI showed a decrease in BMD during the follow-up in preoperatively varus knee joints (p<0.001). In preoperatively valgus knees, there was a slight increase in medial compartment BMD which was not significant (p=0.2). Alignment correction in both groups showed bone remodeling giving similar medial and lateral BMD values, suggesting that the bone became equally strong in both compartments of the metaphysis. There was no association between increasing American Knee Society (AKS) scores and bone remodeling. INTERPRETATION: We suggest that this remodeling is caused by postoperative changes in tibial loading. Our results support the clinical importance of recreating proper valgus alignment of the knee joint in the TKA operation, thus possibly providing better conditions for longevity of the tibial component.