Osteodensitometry measurements of periprosthetic bone using dual energy X-ray absorptiometry following total knee arthroplasty

Introduction

The present study investigates the reaction of bone density as well as the possible factors influencing this reaction following a cement-free total knee arthroplasty (TKA).

Materials and methods

Osteodensitometry scan data from 50 prospective patients with TKA was evaluated. The patients were split into two groups according to the number of follow-up investigations undertaken. No patient included in the study had received medication to increase bone density. To identify the changes in periprosthetic bone density, dual energy X-ray absorptiometry (DXA) bone density measurements in defined regions of interest (ROI) were performed over a period of 24?months postoperative. The test parameters included gender, severity of arthrosis, as well as the metric parameters T-score, body mass index, cortical bone marrow index, and the varus alignment for the respective patient.

Results

The most significant changes in bone density were recorded within the first 3?months postoperative, in particular, the highest bone density loss was found in the region of the proximal medial tibia. Moreover, significant gender-specific associations regarding changes in bone density were established.

Conclusion

Finally, results achieved in the present study demonstrate that the fundamental classification in defined ROI proved to be functional and effective.     

Changes in bone mineral density following total knee arthroplasty: a 1-year follow-up study by dual energy X-ray absorptiometry

The assessment of bone density by means of dual energy Xray absorptiometry is a valid option for monitoring bone changes. In this study, time-related bone changes after total knee arthroplasty implantation were assessed in eight postmenopausal women (aged 62–72 years) up to one year from surgery. The pattern of bone changes followed a well-known design: an initial phase of accelerated bone loss and a subsequent phase of partial bone recovery. The greatest bone loss was observed at 2 months after surgery: 5.0% for the whole periprosthetic bone in the AP projection and 11.5% for the bone in the LL projection. In the following ten months the bone loss in the AP projection was completely recovered while the periprosthetic bone evaluated in the LL projection showed a residual bone loss of 9.0%. At 12 months from surgery, the distal femur in LL projection showed the greatest bone loss: 20.0% for the anterior region of interest and 17.0% for the posterior one. A significant correlation was found between the maximum postoperative bone loss and the residual bone loss at 12 months. These results suggest that pharmacological and rehabilitative strategies may be useful for the conservation of bone stock. Received: 9 February 2002, Accepted: 12 February 2002 Correspondence to: C. Trevisn     

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 fractures after total knee arthroplasty

The increasing implantation rates of knee arthroplasties are associated with a growing prevalence of complications like periprosthetic fractures. Underlying patient, implant and/or operation technique-related risk factors contribute to these fractures which often occur after minor trauma. In the diagnostic process, fracture dislocation, implant stability, and integrity of the extensor mechanism have to be assessed. Valid classification systems are available to guide treatment decisions. Treatment goals are precise reposition, stable fixation, restoration of function, and early mobilization. In the case of an operative revision, the surgeon has to know the implanted device and has to be prepared for extended procedures and revision arthroplasty. Less invasive fixation devices like retrograde nailing or LISS are often sufficient to stabilize femoral supracondylar fractures, while loosening of the implant often requires extended exchange arthroplasty. Tibial fractures are often associated with osteolysis and bone loss which has to be addressed with bone grafts or augmented revision implants. Long-stemmed implants allow bypassing of the reconstructed defect and provide a stable solution for early mobilization. Patella fractures with stable or asymptomatic implants and continuity of the extensor mechanism should be treated conservatively. If reconstruction becomes necessary, results are often associated with significant functional limitations.     

Metabolic bone disease following gastrectomy: assessment by dual energy X-ray absorptiometry.

Although disorders in bone metabolism have long been recognized as typical sequelae of gastrectomy, there has until now been no reliable method of providing precise assessment of bone mass, resulting in a variation of reported incidence. In this study, metabolic bone disease was evaluated in a well characterized population: 34 men 2-5 years after gastrectomy; 11 men 6-10 years after gastrectomy; eight men 2-5 years after colonic resection; and 115 healthy men. The age range was 50-69 years. An innovative reliable method of dual energy X-ray absorptiometry was used which allows quantitative assessment of bone mineral content. Measurement of lumbar spine bone mineral density revealed that the mean(s.e.m.) bone mineral density in patients who had had a gastrectomy (2-5 years 0.84(0.03) g/cm2, 6-10 years 0.85(0.05) g/cm2) was significantly lower than that of patients who had undergone colonic resection (0.96(0.04) g/cm2) or healthy men (0.96(0.03) g/cm2). This study demonstrates that a high incidence of bone atrophy is induced at the relatively early period of 2-5 years after gastrectomy.     

Periprosthetic fractures after total knee joint arthroplasty

Periprosthetic fractures of the femur, tibia and patella are being registered with increasing frequency due to the rising numbers of total knee replacements. Depending on the site of the fracture, apart from mere traumatic mechanisms, implant specific parameters and implant loosening may represent the main causes of periprosthetic fracture. Moreover, general risk factors promote the manifestation of a periprosthetic fracture. Nowadays, valid classifications are available to categorize periprosthetic fractures of the femur, tibia and patella, and to create the basis for specific decision-making in choice of treatment. Despite a wide field of treatment options, the actual functional outcome after therapy and the high rates of complications imply that an adequate analysis of the fracture etiology and the corresponding transfer into an individualized treatment concept offer the chance of functional restoration of the patient similar to the pre-fracture state.     

Changes in bone mineral density at the proximal tibia after total knee arthroplasty: a 2-year follow-up of 28 knees using dual energy X-ray absorptiometry.

The change in bone mineral density at the proximal tibia during 2 years after total knee arthroplasty was studied in 28 knees (28 patients: 10 men and 18 women; median age: 71 years) with dual energy x-ray absorptiometry. Bone mineral density was measured at the proximal tibia at nine regions of interest below the tibial component within 1 week after the operation (baseline); measurements were repeated at 3, 6, 12, and 24 months. All but one knee was malaligned before the operation, and all but three were corrected to within the normal range of alignment after it. The mean bone mineral density of all nine regions of interest at the proximal tibia temporarily decreased by 13% (p = 0.001) during the initial 3 months, probably due to a general metabolic reaction of the skeleton to the operative trauma combined with the effect of the postoperative immobilization, and then the initial level was regained for as long as 2 years. The overall changes in mean bone mineral density to 2 years were insignificant (p > 0.05); however, a great variation (43.9% decrease to 98.0% increase) was observed on an individual basis. This change over time was significantly associated (R2 = 0.36, p = 0.002) with the level of the baseline bone mineral density, which in turn was partly related (R2 = 0.24, p = 0.009) to the amount of malalignment of the knee before the operation. Knees with high baseline levels (n = 14: 11 with varus and three with valgus alignment) displayed a decrease of 10.0 +/- 14.0% (mean +/- SD, p > 0.05) for as long as 2 years, whereas those with low baseline levels (n = 14: seven with varus and six with valgus alignment and one neutrally aligned) had an increase of 19.1 +/- 38.2% (p = 0.038). In both groups, the mean bone mineral density converged to a level of 0.75-0.95 g/cm2 at 2 years.     

Periprosthetic bone mineral density of the distal femur after total knee arthroplasty

Summary Evaluation of the bone mineral density (BMD) was performed in the distal femur around the femoral component of a total knee prosthesis. A total of 48 females were enrolled for this study, including 14 with osteoarthritis of one knee undergoing total knee arthroplasty (TKA) with an Osteonics prosthesis, 14 with osteoarthritis of one knee undergoing TKA with a Whiteside prosthesis, and 20 age-matched normal controls. The BMDs of both knees were measured before operation, and then at 3, 6 and 12 months after operation. The preliminary results demonstrate a significant progressive decrease of BMD in the distal femur of the operated knees after TKA, whereas the BMD of the non-operated knees remains stable. The ratio of BMD between the operated femur and the non-operated femur began to decrease 6 months after operation, and was most obvious at the end of the first year (ranging from 7% to 27%). Further investigation is essential to determine the clinical significance of this loss of periprosthetic bone.

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Résumé L'étude de la densité minérale osseuse (DMO) du fémur distal porteur d'une prothèse totale a été réalisée. Quarante-huit femmes ont fait l'objet de cette étude. 14 d'entre-elles présentaient une gonarthrose unilatérale et ont eu une arthroplastie totale avec une prothèse Osteonics; 14 autres, toujours avec une gonarthrose unilatérale ont eu une arthroplastie totale avec une prothèse Whiteside; enfin, 20 patientes, de même tranche d'âges sans arthrose du genou ont servi de groupe témoin. La densité minérale des deux genoux fut mesurée avant l'opération, puis à 3, 6 et 12 mois après intervention. Les résultats préliminaires montrent une diminution progressive et significative de la densité minérale dans le fémur distal des genoux opérés par arthroplastie totale. La densité des genoux non opérés reste stable. Le rapport des densités entre fémur opéré et fémur non opéré commence à décroitre 6 mois après l'opération et est le plus marqué à la fin de la première année (de 7 à 27%). D'autres investigations sont nécessaires pour évaluer la signification clinique de la diminution de densité de l'os périprothétique.

     

Measurement of periprosthetic bone mineral density after cementless hip arthroplasty by dual energy X-ray absorptiometry: Longitudinal and cross-sectional evaluation

To clarify changes in bone mass around a femoral prosthesis, periprosthetic bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) in 60 patients after unilateral cementless hip arthroplasty. Changes in BMD were evaluated by cross-sectional analysis in all patients and by longitudinal analysis in 26 patients who were available for measurement from 1 month to 2 years after surgery. The mean reproducibility of BMD measurements was within 1.74% in vivo. Periprosthetic BMD began to decrease early after surgery, and although it recovered temporarily within 1 year, it did not return to the level of the 1st month even after 2 years. BMD was reduced by 30.4% in the whole periprosthetic region compared with the contralateral untreated femora 4–7 years after surgery. The reduction in BMD was remarkable around the proximal part of the stem, especially in zone 7 (44.7% reduction 4–7 years after surgery). Significant positive correlations were observed between the low level of the preoperative cortical remodelling index and the reduction in BMD and between the preoperative femoral BMD and the reduction in BMD, indicating that the postoperative bone loss was greater in patients who preoperatively showed quantitative and qualitative deterioration of the femur. Abstracts of this paper were presented at the 66th and 67th Annual Meeting of the Japanese Orthopaedic Association, the 19th Conference of Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT), and the 20th Conference of the Japanese Hip Society     

Periprosthetic fractures of the femur after total knee arthroplasty

Periprosthetic fracture following total knee arthroplasty is a potentially serious complication. This injury can involve the distal femur, proximal tibia or the patella. This review article analyzes the prevalence, risk factors, classification and treatment options for periprosthetic fractures of the femur.     

股骨假体周围骨密度定量测定

目的 通过双能X线骨密度仪测定不同情况下股骨假体周围的骨密度变化情况,了解骨丢失与股骨假体松动的关系。方法 分为骨水泥固定的股骨假体组、非骨水泥固定的股骨假体组、股骨假体松动组共3个组,采用LUNAR DPXL-L型双能X线骨密度仅(Lunar Corp Wisconsin,USA)及Orthopaedies软件,分析时用Gruen’s 7区法。结果 骨水泥固定的股骨假体组骨丢失为15．1%～29．3%,非骨水泥固定的股骨假体组骨丢失为13．2％～27．9%,股骨假体松动组骨丢失为25．4％～43．4%,3组均是股骨近端骨丢失明显．骨丢失主要发生在术后8年以内。结论 骨水泥固定的股骨假体和非骨水泥固定的股骨假体周周骨密度降低一样,假体松动者假体周围骨丢失明显增加。股骨近端2个以上区域骨丢失大于35％或术后8年以后突然出现明显的骨丢失,考虑有股骨假体松动存在的可能性。     

Periprosthetic bone loss after cemented total hip arthroplasty

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 fractures around total knee arthroplasty

INTRODUCTION

The number of total knee arthroplasties performed continues to rise annually and it would be expected that complications, which include periprosthetic fractures, will also therefore become more commonplace. This article reviews the current literature regarding this injury and identifies the treatment principles that enable patients to regain optimal function.

METHODS

A comprehensive search of the Pubmed and Embase™ databases was performed to identify relevant articles. Keywords and MeSH (Medical Subject Headings) terms included in the search strategy were ‘periprosthetic fracture(s)’, ‘femur’, ‘tibia’, ‘patella(r)’, ‘complication(s)’, ‘failure(s)’, ‘risk(s)’, ‘prevalence’, ‘incidence’, ‘epidemiology’ and ‘classification(s)’. The search was limited to all articles published in English and reference lists from the original articles were reviewed to identify pertinent articles to include in this review. A total number of 43 studies were identified.

RESULTS

Common treatment aims have been identified when managing patients with a periprosthetic fracture around total knee arthoplasty. The main criterion that determines which option to choose is the degree of remaining bone stock and the amount of fracture displacement.

CONCLUSIONS

Treatment of a periprosthetic fracture around total knee arthroplasty will either be non-operative, osteosynthesis or revision arthroplasty. It is imperative that a suitable option is chosen and based on the published literature, pathways are outlined to aid the surgeon.     

Periprosthetic fractures complicating total knee arthroplasty

Periprosthetic fractures complicating total knee arthroplasty (TKA) occur in rare cases. However, the rate of TKA continues to rise. Given the increase in demand, orthopedists, more than ever, will be responsible for evaluating and treating these fractures. In order to properly treat periprosthetic fractures, a level of comfort with the basic principles on this topic is critical. This article will discuss fractures affecting the femoral, tibial and patellar components along with the respective classification systems. The potential patient risk factors and post-operative rehabilitation guidelines are also discussed.     

Biochemical bone markers compared with bone density measurement by dual energy X-ray absorptiometry

In contrast to medical imaging, the biochemical markers allow a more frequent determination and are not as invasive as histomorphometric methods. We investigated biochemical markers of type I collagen compared with bone density measurements in 85 females between 41 and 89 years of age (median: 57 years). The bone density measurements were performed by dual-energy X-ray absorptiometry (DXA) on the lumbar spine (L_1–4). The bone density measurements were stated as percentage of the norm. All patients were divided into three groups: I=<80%; II=80–120%; III=>120%. Based on this classification the median concentration of the I-carboxyterminal propeptide of type I procollagen in serum (S-PICP) as an anabolic marker of type I collagen increased significantly with rising bone density: I 65.0^* g/liter (interquartile range: 52.1–78.0 g/liter); II 85.9^* g/liter (52.1–115.5 g/liter); III 81.4 g/liter (62.0–101.0 g/liter); ^* P<0.05. The concentration of urinary pyridinolines (U-PYR) as a marker for degradation of type I collagen decreased. The I-carboxyterminal telopeptide (S-ICTP) and osteocalcin (S-BGP) did not change. The multivariate regression analysis showed no relationship between bone density measurement and biochemical bone markers. Only the age significantly correlated negatively with bone density measurement. For a better assessment of type I collagen metabolism we created a b-quotient by dividing the sum of S-PICP and S-BGP by U-PYR. The median b-quotient increased significantly: I 1.55^*+ (0.97–2.04); II 2.09^* (1.57–2.86); III 2.46⁺ (1.58–3.22);^*+ P<0.05. Changes in bone metabolism cannot be identified by the determination of a single marker. However, the improved biochemical diagnostic measurement using the b-quotient may provide early information about the progression of a metabolic disorder within the interval of imaging.     

Quantitative assessment of callus distraction using dual energy X-ray absorptiometry

Summary. Bone mineralisation during and after limb lengthening procedures on the femur or tibia using unilateral fixators has been monitored quantitatively using dual energy X-ray absorptiometry (DEXA). We measured the bone mineral density (BMD) prospectively in the newly formed callus, in the bone adjacent to the callus and in the proximal femur. In twenty-one patients we showed a typical course with a peak value at 4 – 6 weeks after beginning distraction and a minimum value at maximum distraction. In the consolidation period the BMD in the distraction gap increased until the fixator was removed. The BMD in the regenerated bone increased faster in the regions of interest (ROI) opposite the fixator compared to those near it. Dynamisation caused more homogeneous regeneration equalising V _BMD in the different ROIs. The BMD in the proximal femur of the leg which was operated on decreased to 67% and in the opposite leg to 87% of the preoperative value. DEXA provides a precise and quantitative assessment of callus and bone mineralisation during limb lengthening and helps in understanding what is happening during these procedures.

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Résumé. Le processus de la minéralisation peut précisément être étudié d’une manière quantitative pendant et après la distraction du cal au moyen de l’absorptiométrie en énergie-binaire (DEXA) en créant une petite radioexposition. Des patients (n = 21) avec une distraction du cal, auxquels nous avons mesuré prospectivement la densité minérale de l’os (bone mineral density = BMD) dans et autour du cal nouvellement formé, étaient traités avec des fixateurs externes unilatéraux. La minéralisation a montré une courbe typique avec une première pointe de valeur [0,365 +/– 0,196 g/cm ² (30,9% de la première valeur)] à 4 – 6 semaines après le début de la distraction. Une valeur minimale apparut à la distraction maximale. Dans la période de consolidation la BMD est montèe jusqu’au moment de l’enlèvement du fixateur à 1,020 +/– 0,234 g/cm² (87%). La minéralisation du cal, mésurée grace à la technique des ?regions of interest (ROIs)?, augmenté plus vite aux ROIs éloignées qu’aux ROIs très proches du fixateur. De la dynamisation du fixateur résulte une vitesse de minéralisation plus homogène. Nous considérons la DEXA comme une méthode précise pour étudier les processus de la minéralisation et du développement du cal pendant la distraction avec un fixateur unilatéral. En tenant compte des limites de la technique, la DEXA – qui nous livre des valeurs quantitatives – nous aide à comprendre ce qui se passe pendant la distraction.

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Accepted: 11 July 1996     

膝关节假体周围骨折

全膝关节置换术后假体周围骨折仍然是对骨科医生的挑战性难题.膝关节假体周围骨折的成功治疗取决于假体的稳定性、远端骨骨量及骨折复位程度;Kim分类法有助于选择正确的治疗方法;治疗目的旨在恢复功能及缓解疼痛,多数病人能够达到此要求,但应尽量避免并发症.该文就全膝关节置换术后假体周围骨折的发病率、分类方法、治疗措施和预后情况作一综述.     

Bone mineral density of the distal femur following uncemented total knee arthroplasty: a two-year follow-up of 11 knees using dual energy X-ray absorptiometry

Abstract In a prospective study, we evaluated the adaptive bone remodelling pattern of the distal femur using dual energy X-ray absorptiometry (DEXA) after total knee arthroplasty (TKA). Eleven patients underwent TKA with insertion of an Interax total knee system (Howmedica) because of primary osteoarthrosis of the knee. All patients received an uncemented femoral component with an uncoated cast-mesh ingrowth surface. The components had a 20-mm long central peg placed anteriorly just behind the anterior flange. DEXA scans were performed postoperatively at 2 weeks and at 3, 6, 12 and 24 months in the mediolateral plane of the distal femur and in the anteroposterior plane of the distal tibia and fibula. Compared to the immediate 2-week postoperative bone mineral density (BMD) value, we found no significant changes in BMD in 4 regions of interest (ROI) in the distal femur during the 2-year follow-up at 3 months. A temporary but significant decrease in BMD of 11.2% (95% CL, -17.3% to -5.0%) was observed in the most distal ROI just posterior to the fixation peg. Bone mineral content (BMC) of the distal tibia and fibula showed no significant changes in the operated and contralateral legs during the follow-up. The adaptive bone remodelling of the distal femur after TKA using an uncemented femoral component not previously examined by DEXA induced only a very limited and temporary loss of bone mineral.     

Changes in volumetric bone mineral density after gastrectomy as assessed by dual energy X-ray absorptiometry.

We used dual energy X-ray absorptiometry (DXA) to study changes in estimated volumetric bone mineral density (EstVBMD) of the lumbar spine after gastrectomy. The study group comprised 41 men and 32 women. When EstVBMD was compared according to sex among patients younger than 60 years of age, patients 60 to 69 years of age, and patients these three groups in men (0.185 g/cm3, 0.187 g/cm3, 0.187 g/cm3, respectively). In contrast, EstVBMD was significantly lower in women 60 to 69 years of age (0.157 g/cm3) and those 70 years of age or older (0.159 g/cm3) than in women younger than 60 years (0.200 g/cm3) (P < 0.01). When the relation between EstVBMD and the number of months after gastrectomy was studied according to sex in patients younger than 70 years, EstVBMD negatively correlated with the interval after operation in men (r = -0.365, P < 0.05), whereas there was no correlation between these variables in women. These results suggest that after gastrectomy bone mineral density decreases gradually in men younger than 70 years, but not in women. The lack of a consistent change in bone mineral density after gastrectomy in women is apparently caused by the marked effect on bone metabolism of decreased female hormone levels after menopause.