Bone mineral measurements at the knee using dual photon and dual energy X-ray absorptiometry: Methodological evaluation and clinical studies focusing on adaptive bone remodeling following lower extremity fracture, total knee arthroplasty, and partial versus total meniscectomy

No difference for changes in BMD between two different cementless hip stem designs 2 years after THA

This study evaluates how 2 different total hip arthroplasty (THA) stems compares regarding adaptive bone remodelling. The stems are both proximally porous coated, aiming for proximal fixation, but with different dispersal of the coating. They are also differently designed regarding the distal tip of the stem. We aimed to investigate if there is a difference in periprosthetic adaptive bone remodelling between two different designs. From February 2016 to September 2017, we randomised 62 patients, 1:1 (mean age = 64 years, Female/Male = 28/34), scheduled for an uncemented THA to receive either an EBM or a BM THA stem. We performed dual-energy x-ray absorptiometry (DEXA) scans within a week after surgery and at 3, 6, 12 and 24 months with measurements of bone mineral density (BMD) in the 7 Gruen zones (region of interest (ROI) 1–7). Additionally, Oxford Hip Score and Harris Hip Score were collected at 6, 12 and 24 months. We found a decrease in BMD between the postoperative and the 24-months values in all ROIs for both stems. The greatest decrease over time was seen for both groups in the ROI1 (BM = − 8.4%, p = 0.044, and EBM = − 6.5%, p = 0.001) and ROI7 (BM = − 7%, p = 0.005, and EBM = − 8.6%, p < 0.0005). We found a tendency in ROI2–4 of a higher degree of bone loss in the EBM group. However, this difference only continued beyond 6 months in ROI4 (24 months: BM = − 1.2% and EBM = − 2.8%, p = 0.001). The stems show similar adaptive bone remodelling and are clinically performing well.

Evaluation of different coatings of the tibial tray in uncemented total knee arthroplasty. A randomized controlled trial with 5 years follow-up with RSA and DEXA

BACKGROUND

Regenerex® is a porous titanium construct with a 3D interconnecting pore structure and biomechanical characteristics close to that of normal trabecular bone. This study aimed to compare the Regenerex (VR) to the non-interconnecting pore structure Porous Plasma Spray (VP) on tibial implants for total knee arthroplasty (TKA) at 5 years.

METHODS

We enrolled and randomized 61 patients (mean age = 63(49-71) years, Female/Male = 35/26) who were planned for an uncemented Vanguard TKA (Biomet, Warsaw, Indiana, USA) to receive either a VR or a VP coated tibial component (31/29). We performed radiostereometric analysis (RSA) and Dual Energy X-ray Absorptiometry (DEXA) postoperatively, and at three, six, 12, 24 and 60 months with measurements of migration. In total 55 patients attended the 5-year follow-up.

RESULTS

One patient died and four were reoperated during the 60-months period; none due to aseptic loosening. All reoperations were in the VR-group. The mean (range) 60-months MTPM was 1.4 mm (0.5-3.7) for the VP-group and 1.8 mm (0.4-4.9) for the VR-group (p = 0.8). The 24 to 60-months mean (range) MTPM was -0.3 mm (-5 to 1.24) in the VP-group and 0.2 mm (-0.4 to 3.5) in the VR-group (p = 0.8).

CONCLUSION

We did not find any statistically significant differences between the VP- and VR-group and both groups show recognizable migration. We will continue to follow the groups for years to come.

Two-year follow-up of bone mineral density changes in the knee after meniscal allograft transplantation: Results of an explorative study

BACKGROUND

The potential chondroprotective effect of meniscal allograft transplantation (MAT) is unclear. Subchondral bone mineral density (BMD) and subchondral bone remodeling play important roles in osteoarthritis development. Evaluation of subchondral BMD after MAT might give more insight into the potential chondroprotective effect. The purpose of this study was to determine early BMD changes in the knee after MAT.

METHODS

Twenty-six consecutive patients underwent MAT during 2010-2013. The BMD was measured using dual-energy x-ray absorptiometry (DXA) scan preoperatively, and six months, one and two years postoperatively. Bone mineral density was measured in six regions of interest (ROIs) in the tibia and femur (medial, central, lateral) in both treated and healthy contralateral knees.

RESULTS

The BMD levels of MAT knees did not significantly change during two years of follow-up in almost all ROIs. Bone mineral density was significant higher in nearly all ROIs in MAT knees at almost all follow-ups compared to healthy contralateral knees. In the healthy contralateral knees, BMD slightly, but not statistically, decreased in the first postoperative year, where it normalized to baseline values at two-year follow-up. The BMD levels in all ROIs did not significantly differ between the patients with or without chondropathy at baseline and two-year follow-up.

CONCLUSION

Based on the findings, MAT did not show a significant influence on BMD in the first two postoperative years. Longer follow-up is necessary to prove the potential chondroprotective effect of MAT using BMD measurements.

Natural Course of Local Bone Mineralization After Treatment of Benign or Borderline Bone Tumors and Cysts With a Composite Ceramic Bone Graft Substitute

After surgical bone tumor removal, filling of the bone defect is frequently performed using a bone graft or bone graft substitute. During follow-up, precise quantification of changes in bone mineral density, within the treated bone defect, is very difficult using conventional X-ray examinations. The objectives of this study were to characterize the pattern of resorption/biodegradation of a composite calcium sulfate/hydroxyapatite bone graft substitute and to quantify the bone defect healing with repeated dual-energy X-ray absorptiometry (DXA) measurements. Seventeen patients treated for 18 benign bone lesions, with subsequent defect filling using 2 variants of a composite ceramic bone graft substitute (CERAMENT™|BONE VOID FILLER or CERMAMENT™|G, BONESUPPORT AB, Lund, Sweden), were scanned postoperatively and after 2, 6, 12, 26, and 52 wk using DXA. After an initial increase in bone mineral density after implantation of the bone graft substitute, bone mineral density decreased in the bone defect region throughout the 52 wk: rapidly in the first 12 wk and slower in the remaining weeks. Despite this continuous decrease, bone mineral density remained, on average, 25% higher in the operated extremity, compared with the nonoperated extremity, after 52 wk. The observed pattern of reduction in bone mineral density is consistent with the anticipated resorption of calcium sulfate within the bone graft substitute during the first 12 wk after surgery. We believe the DXA technique provides a precise method for quantification of bone graft resorption, but for evaluation of new bone formation, 3-dimensional imaging is needed.

Radiographic and clinical results after surgically treated tibial plateau fractures at three and twenty two years postsurgery

PURPOSE

We examined the development of osteoarthritis (OA) and post-traumatic bone loss after surgery for tibial plateau fractures (TPF).

METHODS

Patients who had participated in previous follow-up (FU) examinations after TPF and primary reduction and internal fixation were re-evaluated. At the first FU, a median of three years after the accident (short-term FU), the patients underwent functional assessments and standardised X-rays to grade radiological OA and post-traumatic bone loss. At the second FU, a median of 22 years after the accident (long-term FU), 30 patients were available. An identical protocol was applied, and additional investigations [Knee Injury and Osteoarthritis Outcome Score (KOOS) and magnetic resonance imaging (MRI) of the injured knee] were performed.

RESULTS

When the subjective and objective results at first FU were compared with those of the second FU for the same patients, deterioration of symptoms, signs and radiological OA was noted; however, ten patients had no OA even after the long-term FU. Some patients developed post-traumatic bone loss. In 13 of 31 knees, there was little or no radiological evidence of bone loss at the second FU.

CONCLUSIONS

The short-term FU examination results after TPF have little prognostic value for the individual patient, as good results may deteriorate over the long run; however, there were some knees with no OA at the long-term FU. This is the first report focusing on post-traumatic bone loss after TPF.

Do porous tantalum implants help preserve bone?: evaluation of tibial bone density surrounding tantalum tibial implants in TKA

BACKGROUND

TKA with conventional metal-backed tibial implants subjects the tibial metaphysis to stress shielding, with resultant loss of bone density.

QUESTIONS/PURPOSES

We hypothesized tibial bone mineral density in patients with porous tantalum (trabecular metal) tibial baseplates would (1) more closely parallel tibial bone mineral density in the nonoperative control limb and (2) be better maintained than in conventional historical controls.

PATIENTS AND METHODS

We prospectively followed 41 patients (35 men, six women) 60 years of age or younger undergoing TKA with uncemented trabecular metal tibial components. Patients underwent dual-energy xray absorptiometry scans of both proximal tibiae preoperatively and at 2 months, 1 year, and 2 years postoperatively. We determined bone mineral density in three selected regions of interest (Zone 1, between the pegs; Zone 2, beneath the pegs; Zone 3, directly below entire baseplate). Precision analysis revealed a precision error of 4% or less for each region of interest, indicating adequate power to detect bone mineral density changes of 8% or greater.

RESULTS

Bone mineral density percent change was different between the operative and nonoperative knees only in Zone 3 and only at 2 months. There was no change in bone mineral density in any zone in the nonoperative knee at any time. Only in Zone 3 did the bone mineral density decrease at 2 months in the operative knee.

CONCLUSIONS

Trabecular metal implants appear to maintain tibial bone mineral density in a parallel fashion to the nonoperative limb in this population and better than historical controls.

DXA scanning of acetabulum in patients with cementless total hip arthroplasty

The aim of this study was to evaluate the reproducibility of bone mineral density (BMD) measurements of the periprosthetic bone in patients with hemispherical acetabular cups in cementless total hip arthroplasty (THA). Thirty patients were treated for primary osteoarthrosis with cementless THA. Dual-energy X-ray absorptiometry (DXA) scanning was performed with a pencil-beam bone densitometer (Norland XR-36). Accuracy and reproducibility was determined by double measurements of BMD in four regions of interest (ROI). The influence of patient postures including various pelvic inclination angles was evaluated as well. Pitman test for a combined netROI revealed a standard deviation ratio of 3.2 for the anterio-posterior scans related to the lateral position. The Wilkinson ROIs showed a high intraobserver agreement. With pelvic tilt increasing until 20 degrees , the precision of DXA scanning decreased. In conclusion, reproducibility of DXA scanning was high. This study demonstrated that the patients can be scanned in the supine position, and BMD measurement of the periacetabular bone can be performed using the Wilkinson model with four rectangular ROIs.

Morphological characteristics of total joint arthroplasty-derived ultra-high molecular weight polyethylene (UHMWPE) wear debris that provoke inflammation in a murine model of inflammation

It is recognized that the chronic inflammation in peri-prosthetic tissue that contributes to implant failure frequently is provoked by the presence of wear debris. Some wear debris is inevitable because of the nature of the prosthesis, but not all patients develop severe inflammatory responses. The precise factors that mediate the severity of tissue inflammation to wear debris has yet to be fully defined. Because wear debris retrieved from peri-prosthetic tissue consists of a heterogeneous mixture of materials with various sizes and shapes, this study evaluated the influence of two major physical aspects of ultra-high molecular weight polyethylene (UHMWPE) wear debris (shape and surface texture) using a model of tissue inflammation. UHMWPE debris particulates recovered from 50 peri-prosthetic tissue samples were examined by scanning electron microscopy and categorized into four groups based upon aspect ratio and surface texture of the material. The four groups were defined as: 1) smooth and globular, 2) smooth and fibular, 3) rough and globular, and 4) rough and fibular. Histological analysis and ELISA assays were conducted to evaluate variations in cellular responses and cytokine production between the groups. The strongest expression of tumor necrosis factor alpha and interleukin-1 beta was found in tissues exposed to UHMWPE debris with both a rough surface texture and fibular shape, and this response was significantly elevated over debris particles with a smooth surface texture and globular shape. The data suggest that both shape and texture influence the severity of specific inflammatory responses and that rough debris surface texture exerts a marked effect on adverse tissue responses when combined with particles that have a sharp, elongated shape.