Posterior Cruciate Ligament Resection Does Not Consistently Increase the Flexion Space in Contemporary Total Knee Arthroplasty

IntroductionIt is accepted dogma in total knee arthroplasty (TKA) that resecting the posterior cruciate ligament (PCL) increases the flexion-space by approximately 4mm. Unfortunately, this doctrine is based on historical studies of limited size with variable technique. The aim of this study was to determine the effect of PCL-resection on in vivo tibiofemoral joint space dimensions in a cohort of modern TKAs.MethodsTibiofemoral joint space measurements were made during 129 standardized TKAs by two arthroplasty surgeons. A medial parapatellar approach, computer navigation and provisional bone cuts were performed in all cases with particular attention to preserving PCL integrity. The tibiofemoral gap was measured with a calibrated tension device at extension, 45-degrees, and 90-degrees before and after complete PCL-resection.Results51% of patients were female (66/129) with mean age and BMI of 69.5 years and 34.2 kg/m², respectively. After PCL-resection, mean change in center joint space dimension increased 0.33mm at extension, 0.95mm at 45-degrees, and 1.71mm at 90-degrees (P < .001). The 90-degree flexion-space opened ≥4mm in only 10% of patients. Dividing the flexion-space change by femoral implant dimension to account for patient size, the flexion-space at 90-degrees significantly increased more in females compared to males (P = .020).ConclusionThe tibiofemoral joint space increased progressively from extension to mid-flexion through deep-flexion after PCL-resection, yet was substantially less than reported in historical studies. However, large variation in flexion-space opening was observed with some patients failing to increase the flexion-space whatsoever with PCL-resection. This runs counter to conventional TKA understanding and should be considered in modern surgical education.Level of EvidenceTherapeutic Level III.     

Teriparatide Administration Increases Periprosthetic Bone Mineral Density After Total Knee Arthroplasty: A Prospective Study

Background

Teriparatide is a currently available therapeutic agent for osteoporosis. Previous studies have reported that teriparatide affects periprosthetic bone mineral density (BMD) after total knee arthroplasty (TKA). However, little agreement has been reached concerning the treatment of periprosthetic BMD after TKA with teriparatide. Moreover, BMD in the femoral and tibial sides of the joints together has never been examined. We investigated the efficacy of teriparatide to inhibit BMD loss in the femoral and tibial side and considered complications such as migration and periprosthetic fractures after TKA.

Impact of Valgus vs Varus Mechanical Axis Correction During Primary Total Knee Arthroplasty on Postoperative Periarticular Bone Mineral Density

BackgroundKnee periarticular bone mineral density (BMD) is influenced by limb malalignment. The purpose of this study is to determine if the nature and magnitude of alignment correction (ΔAlign°) performed during primary total knee arthroplasty (TKA) had an impact on BMD at the metaphysis of the distal femur (DFmr) and proximal tibia (PTb).MethodsSeventy-one patients (male = 37 |female = 34; age: 65 ± 2 years) underwent full-length standing X-rays and knee-specific BMD measurements using dual-energy X-ray absorptiometry before and 3 and 6 months following TKA. A t-test was used to compare baseline demographics and knee-specific BMD measures (medial/lateral DFmr/PTb) between patients with preoperative valgus (VAL, N = 18) and varus (VAR, N = 53) malalignment. Pearson correlation analysis was used to determine if ΔAlign° correlated with site-specific knee BMD changes. A 2 (varus/valgus) by 3 (time) analysis of variance was used to compare site-specific BMD (%ΔBMD) changes following TKA. Type I error was set at α = 0.05 for all analyses.ResultsVAR patients had higher preoperative BMD for medial measurement at both the DFmr (VAR: 1.17 ± 0.06 g/cm²; VAL: 1.00 ± 0.09 g/cm²) and PTb (VAR: 1.41 ± 0.07 g/cm²; VAL: 1.29 ± 0.14 g/cm²) (P < .05). ΔAlign° and %ΔBMD were correlated on the medial side of the DFmr (r = 0.393, P < .05) and lateral/medial BMD ratio at the PTb (r = ?0.670, P < .01) in VAL patients. Only VAL patients had significant %ΔBMD changes at 6 months postoperative with increases on the medial side only for the DFmr and PTb (+4%-8%, P < .05).ConclusionValgus patients exhibited reduced medial BMD at DFmr and PTb and showed sustained improvements 6 months postsurgery. Mechanical axis correction may be clinically impactful to bone remodeling when correcting valgus malalignment.Level of EvidenceLevel II, prospective cohort study.     

Factors Associated With Posterior Cruciate Ligament Tightness During Cruciate-Retaining Total Knee Arthroplasty

Background

The purpose of our study was to identify factors affecting posterior cruciate ligament (PCL) tightness during cruciate-retaining total knee arthroplasty.

Changes in Bone Mineral Density of Both Proximal Femurs after Total Knee Arthroplasty

Background

This study investigated the effects of total knee arthroplasty (TKA) on bone mineral density (BMD) of the proximal femur in patients who underwent the procedure.

Methods

Forty-eight patients scheduled to undergo unilateral TKA because of primary knee osteoarthritis were included in this study, which was conducted at a medical center between October 2006 and October 2009. In these 48 patients, 96 hips were evaluated. Measurement of BMD was performed preoperatively and one month, three months, six months, and one year after unilateral TKA. Repeated measured analysis of variance and paired t-tests for comparison of two repeated samples were used to compare differences between time points (preoperation, one, three, six, and 12 months) and between the operative and nonoperative sides.

Results

Preoperatively, BMD of the femoral neck, trochanter, and total hip on the operative side were lower than on the nonoperative side; however, there was no statistical difference. BMD of both femoral neck areas was significantly lower than preoperative BMD at one month and three months after TKA. BMD of both trochanter areas was significantly lower than preoperative BMD at one month and three months after TKA. BMD of both total hips was significantly lower than preoperative BMD at three months after TKA. However, no statistical differences of changes in BMD were observed between the operative and nonoperative sides at each measurement time.

Conclusions

According to our results, TKA was found to affect both proximal femurs during the acute period. However, TKA did not affect a change in BMD of the proximal femur during one year postoperative.     

Bone Mineral Density of the Femur in Autopsy Retrieved Total Knee Arthroplasties

Bone mineral density (BMD), as measured by DEXA, can vary depending on bone rotation and fat content of soft tissues. We performed DEXA measurements, under controlled positioning, on 24 autopsy-retrieved femora from patients who had fully functional and asymptomatic successful TKA to determine periprosthetic BMD changes and compared results to 24 normal cadaveric femora. In TKA specimens, BMD was affected by gender, preoperative diagnosis, and zone under analysis. The lowest mean BMD was in the anterior femoral condylar zone. Males had higher mean BMD at all zones while patients with preoperative diagnosis of osteoarthritis had higher BMD in the posterior condylar zone. The mean BMD in the anterior femoral condylar zone in TKA specimens was significantly lower than in normal specimens without arthroplasties, most likely due to stress shielding.     

Porous Tantalum Tibial Component Prevents Periprosthetic Loss of Bone Mineral Density After Total Knee Arthroplasty for Five Years—A Matched Cohort Study

In 21 knees receiving porous tantalum tibial component and 21 knees receiving a cemented cobalt-chromium tibial component, dual x-ray absorptiometry scans were performed for five years post-operatively. The postoperative decrease in the bone mineral density in the lateral aspect of the tibia was significantly less in knees with porous tantalum tibial components (11.6%) than in knees with cemented cobalt-chromium tibial components (29.6%) at five years (p < 0.05). No prosthetic migration or periprosthetic fracture was detected in either group. The present study is one of the studies with the longest follow-up period on bone mineral density after total knee arthroplasty. Porous tantalum tibial component has a favorable effect on the bone mineral density of the proximal tibia after total knee arthroplasty up to five years.     

Changes in Bone Mineral Density of the Acetabulum and Proximal Femur After Total Hip Resurfacing Arthroplasty

Our aim was to investigate the changes in bone mineral density (BMD) of acetabulum and proximal femur after total hip resurfacing arthroplasty. A comparative study was carried out on 51 hips in 48 patients. Group A consisted of 25 patients (26 hips) who had undergone total hip resurfacing and group B consisted of 23 patients (25 hips) who had had large-diameter metal-on-metal total hip arthroplasty (THA). BMDs around the acetabulum and proximal femur were measured using dual-energy x-ray absorptiometry (DEXA) at 2 weeks, 6 months, 1 year and annually thereafter during the 3 years after surgery. At final follow-up, the acetabular net mean BMD decreased by 11% in group A and 10% in group B with no differences between two groups (P = .35). For the femoral side, in Gruen zone 1, the mean BMD increased by 4% in group A, whereas it decreased by 11% in group B (P = .029). In Gruen zone 7, the mean BMD increased by 8% at the final follow-up in group A, whereas it decreased by 13% in group B (P = .02). In both groups the mean BMD increased by 3% in Gruen zones 3, 4, 5, and 6. Stress-related bone loss of the acetabulum was comparable for MOM THA and resurfacing devices, but proximal femoral bone density increased in the resurfacing group and decreased in the THA group.     

Preoperative Systemic Bone Quality Does Not Affect Tibial Component Migration in Knee Arthroplasty: A 2-Year Radiostereometric Analysis of a Hundred Consecutive Patients

BackgroundBone quality and other preoperative predictive factors may affect implant migration and the survival of knee arthroplasty.MethodsIn a prospective cohort of 100 consecutive patients (65 women) at a mean age of 67.7 years (range 39-87 years), we investigated preoperative predictors of postoperative tibial component migration in cemented and cementless total knee arthroplasties or cemented unicompartmental knee arthroplasty. Predictors consisted of Knee Injury and Osteoarthritis Outcome Score (KOOS) and Oxford Knee Score, questionnaires, bone turnover markers of CTX and P1NP, systemic bone mineral density (BMD), and knee osteoarthritis (OA) grade. Tibial component migration was measured with radiostereometry postoperative, at 1 and 2 years of follow-up.ResultsBetween 1 and 2 years, 19 tibial components migrated continuously (maximum total point motion [MTPM] > 0.2 mm). In general, there was no difference in age, body mass index, BMD, KOOSs, or OA grade between patients with continuous tibial migration compared to patients without continuous migration (P > .11). However, cementless tibial components with continuous migration had a lower KOOS pain score (more pain), lower vitamin D, and a higher bone turnover (CTX) value than patients without continuous migration. There was no association between the BMD and MTPM at 1-year follow-up regardless of prothesis type (P > .17). Patients with osteoporosis and normal BMD had similar mean tibial component MTPM at 2 years (3 prostheses combined; P = .34).ConclusionMigration of tibial components inserted with or without bone cement was not affected by the preoperative bone quality in terms of systemic BMD, bone turnover markers, and OA grade in the knee.     

Interval Between Staged Bilateral Total Knee Arthroplasties Does Not Affect Early Medical or Surgical Complications

BackgroundThe purpose of this study is to evaluate early postoperative surgical and medical complications in patients undergoing staged bilateral total knee arthroplasty (TKA) and determine if the interval to the second stage influences the risk of complications.MethodsA retrospective review was performed from 2016 through 2018 of all staged bilateral primary TKA procedures, yielding a cohort of 1005 patients (2010 TKAs). Four groups were created based on the timing of the second stage: 3 to 6 weeks, 7 to 12 weeks, 13 to 24 weeks, and >24 weeks. Clinical data compared between groups included demographics, knee range of motion, University of California, Los Angeles (UCLA) activity score, Knee Society pain score, Knee Society clinical score, and Knee Society functional score. Postoperative complications within 90 days were evaluated, with complications after the second knee being the primary outcome.ResultsThe mean follow-up after second stage was 10.7 months (range, 3 to 37 months). No significant differences were found between groups in the range of motion, Knee Society pain, Knee Society clinical score, Knee Society functional score, or University of California Los Angeles activity score in either the first or second knee. After the first knee surgery, medical complications were highest in the >24-week group. After the second knee, there were no significant difference in manipulation (P = .9), wound complications (P = .7), venous thromboembolism (P = .8), or other medical complications (P = 1) based on the interval duration.ConclusionThe interval between staged TKA did not affect early medical or surgical complications after the second stage. Early clinical and function results were not different based on timing of the second surgery.     

Periacetabular Bone Mineral Density Changes After Resurfacing Hip Arthroplasty Versus Conventional Total Hip Arthroplasty. A Randomized Controlled DEXA Study

A randomized controlled trial was performed to evaluate acetabular bone mineral density (BMD) changes after hip resurfacing (RHA) versus an established conventional total hip arthroplasty (THA). A total of 71 patients were allocated randomly to receive either an RHA press-fit cobalt–chromium cup (n = 38) or a THA with a threaded titanium cup and polyethylene-metal-inlay insert (n = 33). The BMD in five separate periacetabular regions of interest (ROI) was prospectively quantified preoperative until 24 months. We conclude that, in contrast to our hypothesis, periacetabular BMD was better preserved after RHA than after placement of a conventional THA. Long term follow-up studies are necessary to see whether this benefit in bone preservation sustains over longer time periods and whether it is turned into clinical benefits at future revision surgery.     

Patients With Knee Osteoarthritis Have Lower Total Hip Bone Mineral Density in the Symptomatic Leg Than in the Contralateral Hip

Osteoarthritis (OA) of the knee is common in the aging population. In patients with OA, bone mineral density (BMD) is usually increased, but the fracture rate does not appear to be systematically lower than in age-matched healthy controls. The aim of our study was to describe hip BMD in patients presenting with unilateral symptomatic knee OA. Patients with painful knee OA were prospectively included in a single-center, randomized, double-blind, placebo-controlled clinical trial to evaluate the structure-modifying efficacy of an oral chondroitin sulfate treatment on the knee joint. The majority of these patients underwent additional measurements of BMD of their lumbar spine and both hips using dual-energy X-ray absorptiometry (DXA). The hip BMD values of the leg with symptomatic knee OA were compared with the contralateral hip. One-hundred and sixty-one patients (81 men and 80 women; aged 62.6 +/- 9.2 yr, range 40-82 yr) underwent DXA. The median total hip BMD was higher than in age-matched controls, but patients had a relatively lower hip BMD in the knee OA-affected leg (p = 0.001). Our knee OA patients rarely presented with concomitant osteoporosis, but usually had a relatively lower hip BMD on the affected leg. Therefore, we suggest that the hip of the leg with symptomatic knee OA should be measured if DXA is acquired only at one hip. Future studies have to assess whether the relative decrease of BMD at the hip of the leg with knee OA might influence fracture incidence.     

Knee Arthroplasty Component Malrotation Does Not Affect Function or Quality of Life in the Short to Medium Term

BackgroundComponent rotation in total knee arthroplasty is thought to affect patella tracking, flexion gap, and balancing and hence is hypothesized to affect function, pain, and longevity. Few studies have directly correlated post-operative component rotation to function and quality of life in the short to medium term post-operatively, with findings in the current literature conflicting.MethodsA retrospective study of prospectively collected data was used to determine the effect of femoral, tibial, and combined component rotation in primary total knee arthroplasty with primary outcomes being function as measured by the Knee Society Score, pain and quality of life as measured by the Short-Form 12 score, and secondary outcome being prosthesis failure. Malrotation was defined using the current literature as being internally rotated from neutral, or externally rotated greater than 5° for the femoral component, internally rotated greater than 6° for the tibial component, or internally rotated from neutral for the 2 components combined.ResultsNo clinically relevant correlation between function or quality of life and component rotation could be found at 5 years. However, it was noted that those patients with combined component malrotation (femoral rotation added to tibial rotation resulting in overall component internal rotation) improved less in overall pain scores than those that were not malrotated.ConclusionIn the mid-term, component malrotation may result in a decreased level of improvement from pain compared to pre-operative results. However, component malrotation does not make a significant difference to function or quality of life.Level of evidenceLevel III: Therapeutic Study.     

孕期营养干预对产后妇女骨密度的影响

目的观察孕期营养定量指导对产后妇女骨密度的影响。方法对 198例孕妇 (观察组 )于孕 3、7个月分别进行饮食、日常运动量调查及代谢率测定 ,同时进行营养指导 ,并与未接受相关调查与指导的 2 35例孕妇 (对照组 )比较产后 14d骨密度。结果观察组骨密度显著优于对照组 (χ2 =37.35 ,P <0 .0 1)。结论孕期营养定量指导能减少产后妇女骨量的丢失。     

Bi‐Cruciate Retaining Total Knee Arthroplasty Does Not Restore Native Tibiofemoral Articular Contact Kinematics During Gait

Bi‐cruciate retaining (BCR) total knee arthroplasty (TKA) design preserves both anterior and posterior cruciate ligaments with the potential to restore normal posterior femoral rollback and joint kinematics. Abnormal knee kinematics and “paradoxical” anterior femoral translation in conventional TKA designs have been suggested as potential causes of patient dissatisfaction. However, there is a paucity of data on the in vivo kinematics and articular contact behavior of BCR‐TKA. This study aimed to investigate in vivo kinematics, articular contact position, and pivot point location of the BCR‐TKA during gait. In vivo kinematics of 30 patients with unilateral BCR‐TKA during treadmill walking was determined using validated dual fluoroscopic imaging tracking technique. The BCR‐TKA exhibited less extension than the normal healthy knee between heel strike and 48% of gait cycle. Although the average external rotation trend observed for BCR TKA was similar to the normal healthy knee, the range of motion was not fully comparable. The lowest point of the medial condyle showed longer anteroposterior translation excursion than the lateral condyle, leading to a lateral‐pivoting pattern in 60% of BCR TKA patients during stance phase. BCR‐TKA demonstrated no statistical significant differences in anterior–posterior translation as well as varus rotation, when compared to normal healthy knees during the stance phase. However, sagittal plane motion and tibiofemoral articular contact characteristics including pivoting patterns were not fully restored in BCR TKA patients during gait, suggesting that BCR TKA does not restore native tibiofemoral articular contact kinematics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1929–1937, 2019     

A Prospective Assessment of Periprosthetic Bone Mineral Density and Osteoimmunological Biomarkers Variations After Total Knee Replacement Surgery

Aseptic loosening is a major cause of premature failure of total knee replacement (TKR). Variations in periprosthetic bone mineral density (BMD) and osteoimmunological biomarkers levels could help to quantify prosthesis osteointegration and predict early aseptic loosening. The gene expression of 5 selected osteoimmunological biomarkers was evaluated in tibial plateau bone biopsies by real-time polymerase chain reaction and changes in their serum levels after TKR were prospectively evaluated with enzyme-linked immunosorbent assay for 1 yr after surgery. These variations were correlated to changes in periprosthetic BMD. Sixteen patients were evaluated. A statistically significant decrease in serum levels of Sclerostin (p?=?0.0135) was observed immediately after surgery. A specular pattern was observed between dickkopf-related protein 1 and osteoprotegerin expression. No statistically significant changes were detectable in the other study biomarkers. Periprosthetic BMD did not change significantly across the duration of the follow-up. Prosthetic knee surgery has an impact on bone remodeling, in particular on sclerostin expression. Although not showing statistically significant changes, in the patterns of dickkopf-related protein 1, osteoprotegerin, and the ligand of the receptor activator of nuclear factor kappa-B symmetries and correspondences related to the biological activities of these proteins could be identified. Variation in osteoimmunological biomarkers after TKR surgery can help in quantifying prosthesis osteointegration.     

Trabecular Bone Score Is a Valuable Addition to Bone Mineral Density for Bone Quality Assessment in Older Mexican American Women With Type 2 Diabetes

Altered bone quality due to the underlying metabolic changes of type 2 diabetes (T2D) has been hypothesized to affect bone strength, leading to increased fracture risk in patients with T2D. Lumbar spine trabecular bone score (LS-TBS), an indirect measure of trabecular microarchitecture, provides information on bone quality and has been associated with T2D. However, trabecular bone score (TBS) is also affected by demographic patterns and body size, and is expected to be different in people from various ethnic or racial backgrounds. Therefore, it is important to understand associations between T2D and TBS for each ethnic or racial group separately. Although the relationship between TBS and age has been reported to be similar between non-Hispanic Caucasians and Mexican Americans (MAs), data on associations of LS-TBS with T2D in older MAs are lacking. Here, we report associations between TBS and T2D in 149 older MA men and women. Participants are part of a cohort known as the Cameron County Hispanic Cohort in Texas who have high prevalence of obesity and poor glycemic control. Bone mineral density was not altered for MA women with T2D, but was significantly higher in MA men with T2D compared with MA men without diabetes. Low LS-TBS was associated with T2D in women in our study. Although low TBS was associated with older age in men, TBS did not show any significant association with T2D for men. These results are similar to those found in other studies of non-Hispanic whites with diabetes. LS-TBS may add value in diagnosing poor bone quality in older MA women with T2D regardless of bone mineral density scoring.     

Does Bone Mineral Density and Knowledge Influence Health-Related Behaviors of Elderly Men at Risk for Osteoporosis?

To determine if bone mineral density (BMD) substantially influences health-related behaviors in men at risk for osteoporosis, we surveyed 102 men who were participating in a study of prostate cancer and bone loss. Subjects included 68 men with prostate cancer, 44 of whom were hypogonadal on androgen deprivation therapy, and 34 healthy age-matched controls without prostate cancer. At least 6 mo after an initial evaluation, assessment of BMD, and osteoporosis information session, men were administered a questionnaire regarding their healthrelated behaviors. We found that men with osteopenia were 4 times as likely (13%) and men with osteoporosis were more than 10 times as likely (41%) to start taking bisphosphonates compared to men with a normal bone mass (3%, p < 0.0001). Men with low bone mass were more likely to begin taking calcium (p < 0.05) and vitamin D supplements (p < 0.05). Hypogonadal men were 10 times as likely to begin using bisphosphonates (34%) compared to the control group (3%, p < 0.0001) and twice as likely to begin using calcium supplements (57% vs 24%, p < 0.05). Caffeine consumption, alcohol consumption, dietary calcium intake, exercise, and smoking habits were not different in men with osteoporosis or those who were hypogonadal compared to controls. We conclude that men with low bone mass and hypogonadism were more likely to start using bisphosphonates, calcium supplements, and vitamin D supplements after having a bone density test. However, they were not more likely to make significant health-related lifestyle changes after obtaining the results of their bone mass.