Acid attack and cathepsin K in bone resorption around total hip replacement prosthesis.

Normal bone remodeling and pathological bone destruction have been considered to be osteoclast-driven. Osteoclasts are able to attach to bare bone surface and produce an acidic subcellular space. This leads to acid dissolution of hydroxyapatite, allowing cathepsin K to degrade the organic type I collagen-rich osteoid matrix under the acidic condition prevailing in Howship lacunae. Using a sting pH electrode, the interface membrane around a loosened total hip replacement prosthesis was found to be acidic. Confocal laser scanning disclosed irregular demineralization of the bone surface in contact with the acidic interface. Cathepsin K, an acidic collagenolytic enzyme, was found in interface tissue macrophages/giant cells and pseudosynovial fluid. Tissue extracts contained high levels of cathepsin K messenger RNA (mRNA) and protein. These observations suggest the presence of an acid- and cathepsin K-driven pathological mechanism of bone resorption, mediated not by osteoclasts in subosteoclastic space, but rather by the uncontrolled activity of macrophages in extracellular space.     

Factors associated with heterotopic bone formation following total hip replacement

Summary In order to delineate groups of patients suitable for treatment to prevent heterotopic bone formation (HBF) following total hip replacement, 99 patients were examined to evaluate predisposing factors. One year after surgery, HBF was found in 73% of the patients. A significantly increased frequency of HBF was found among men. There was no correlation between age, severity of osteoarthritis, size of osteophytes, or preoperative hip movement and HBF. Previous ipsilateral hip surgery did not increase the risk of HBF. Although not significant, all patients who developed heterotopic bone after previous ipsi- or contralateral hip surgery showed HBF of the same or even a higher grade after the present replacement.Supported by grants from the Vejle County Medical Foundation     

Evaluation of bone metabolism in patients after total hip replacement based on bone turnover markers]

Serum bone markers: N-mid osteocalcin (OCN-Mid) and Cross-Laps were evaluated in 51 patients (15 men and 36 women), age 50-81y. (mean 69) with OA undergoing elective cemented THR. Samples were collected at the day before operation and 3 days, 1, 2, 6 weeks, 3, 6, 12 months after the operation and markers measured by direct chemoluminescency using Modular E-170. Lowest values of both markers were noted at the 3-rd day after operation. Cross-Laps levels rose rapidly reaching highest levels 2 weeks after operation and still were significantly (alpha = 0,05) elevated after 6 weeks. The highest but not statistically significant levels of OCN-Mid were noted after 6 months. After 12 months both markers returned to preoperative values. OCN-Mid/Cross-Laps ratio were lowest after 2 weeks (maximal resorption), then rose over the preoperative value after 3 months, being still significantly elevated after 12 months, indicating that bone formation still occurred. No significant differences were found according to sex, radiolucencies around the endoprosthesis (14 patients) and periarticular ossification (9 patients). Serum bone markers can show the process of bone healing around endoprosthesis, but because of different basic levels of bone metabolism, evaluation of this process can be achieved only with comparison to preoperative values.     

Heterotopic bone formation after total hip arthroplasty.

Formation of heterotopic bone can cause pain and limit motion, thus ruin what would otherwise have been an excellent result after total hip arthroplasty. The cause of bone formation remains controversial, and diphosphonates have been ineffective in its prevention. Radiotherapy and nonsteroidal anti-inflammatory drugs, however, are effective preventative agents. Once the bone is formed, however, surgical excision is the only effective treatment.     

Heterotopic bone formation after total hip arthroplasty.

Heterotopic bone formation is a common complication of total hip arthroplasty. A certain degree of heterotopic bone formation occurs in about one-half of the patients in degrees ranging from very mild to moderate involvement. The patients do not necessarily have any clinical disability; only 2 per cent of the patients developed severe heterotopic bone radiographically, and unsatisfactory functional results. There is no sex predilection for heterotopic bone formation except that the condition appears more severe in females. All ages are equally affected. The underlying disease process in the hip does not influence the occurrence of heterotopic bone. The incidence was significantly greater in patients who developed postoperative hematomas, prolonged wound drainage, or superficial infection. When surgical exposure is difficult and retraction of soft tissue aand soft tissue damage takes place, the incidence is much greater. Patients who have undergone previous surgical procedures about the hip present a greater risk in regards to development of disabling heterotopic bone formation.The etiology of heterotopic bone formation is not known. The following steps should be taken to avoid or greatly minimize the development of heterotopic bone: meticulous exposure with most careful retraction, copious irrigation with antibiotic solution, debridement of devitalized tissue prior to closure, instillation of drainage tubes, intraoperative and postoperative antibiotics, and carefully controlled postoperative anticoagulation.     

Increased bone resorption and decreased bone formation in Chinese patients with hip fracture

Biochemical markers of bone formation (bone-specific alkaline phosphatase and osteocalcin) and bone resorption (hydroxyproline excretion and bone isoenzyme of acid phosphatase) were measured in 30 patients (15 M and 15 F) with hip fracture and 30 healthy subjects matched for age and sex. Bone isoenzyme of tartrate-resistant acid phosphatase (TRACP) was measured by a recently developed specific immunoassay. Serum osteocalcin concentration and bone-specific alkaline phosphatase activity were significantly lower and serum TRACP concentration and urinary hydroxyproline excretion were elevated in patients compared with healthy subjects. We suggest that there is reduced bone formation and increased bone resorption in patients with hip fracture.     

Socioeconomic status affects the early outcome of total hip replacement

This prospective study assessed the effect of social deprivation on the Oxford hip score at one year after total hip replacement. An analysis of 1312 patients undergoing 1359 primary total hip replacements for symptomatic osteoarthritis was performed over a 35-month period. Social deprivation was assessed using the Carstairs index. Those patients who were most deprived underwent surgery at an earlier age (p = 0.04), had more comorbidities (p = 0.02), increased severity of symptoms at presentation (p = 0.001), and were not as satisfied with their outcome (p = 0.03) compared with more affluent patients. There was a significant improvement in Oxford scores at 12 months relative to pre-operative scores for all socioeconomic categories (p < 0.001). Social deprivation was a significant independent predictor of mean improvement in Oxford scores at 12 months, after adjusting for confounding variables (p = 0.001). Deprivation was also associated with an increased risk of dislocation (odds ratio 5.3, p < 0.001) and mortality at 90 days (odds ratio 3.2, p = 0.02). Outcome, risk of dislocation and early mortality after a total hip replacement are affected by the socioeconomic status of the patient.     

Risedronate reduces postoperative bone resorption after cementless total hip arthroplasty

Summary Forty-three patients who had undergone cementless THA were randomly assigned to receive no osteoactive drug or oral risedronate for 6 months. Postoperative decrease of BMD in the risedronate group was significantly lower than that seen in the control group in zones 1, 2, 3, 6, and 7. Introduction Proximal bone resorption around the femoral stem often has been observed after total hip arthroplasty (THA), could lead to late stem loosening. We previously reported the efficacy of etidronate on periprosthetic bone resorption after cementless THA. Recently risedronate is suggested to be effective for the prevention and treatment of for osteoporosis. The purpose of the present study was to evaluate the effects of risedronate on periprosthetic bone loss after cementless THA. Methods Forty-three patients who had undergone cementless THA were randomly assigned to receive no osteoactive drug (21 patients) or oral risedronate 2.5 mg/day (22 patients) for 6 months. Three patients were eliminated from the risedronate group because of dyspepsia. Periprosthetic bone mineral density (BMD) in seven regions of interest based on the zones of Gruen et al. was measured with dual energy X-ray absorptiometry at 3 weeks and 6 months postoperatively. Results At 6 months after surgery, postoperative decrease of BMD in the risedronate group was significantly lower than that seen in the control group in zones 1, 2, 3, 6, and 7 (p < 0.05, p < 0.01, p < 0.01, p < 0.05, and p < 0.05, respectively). Conclusion These outcomes suggested that risedronate might reduce the periprosthetic bone resorption after cementless THA.     

Ectopic bone formation after total hip arthroplasty

Ectopic bone formation (EBF) is a well-known complication of total hip arthroplasty (THA). The etiology and pathogenesis are still obscure. An analysis of 119 consecutive patients with 129 primary THAs was performed to identify factors predisposing to ectopic bone formation, its frequency, and its effect on the results. Gender (male) and the duration of the operative procedure were statistically significant factors in the development of ectopic bone, which occurred in 63% of hips. The effect of grade III EBF on THA was a limited range of movement. Both local and systemic factors seem to play a role in the development of ectopic bone. Gentle handling of tissues may be important if the rate of ectopic bone is to be reduced.     

A knowledge-based computer-aided design and manufacturing system for total hip replacement.

A knowledge-based computer-aided design and manufacturing system (CAD-CAM) has been developed for total hip replacement. Knowledge-based refers to the fact that the design process is a computer program that has been provided with preprogrammed design rules. Compared with conventional CAD-CAM systems, the knowledge-based system is automated, requires less designer intervention, and increases the accuracy of the design process. The capabilities of the system make it ideal for the design of standard and custom total hip replacement. A full-fill, press-fit custom total hip replacement has been designed using the knowledge-based system. The early clinical results of a series of 37 replacements in 31 patients is described in this paper.     

Loss of bone mass after total hip replacement: preliminary data.

In a total of 37 females with cemented total hip replacement for monolateral coxarthrosis, of which 13 with prosthetic stem loosening, and 11 with monolateral coxarthrosis that is not prosthetized, bone mineral density (BMD) is determined by dual ray photonic absorbimetry selecting regions of interest (ROI) on the cortex of the femurs 4 cm under the lesser trochanter and on the ischium bilaterally. In females that are not prosthetized there are differences in bone mass between the two femurs and the ischium on both sides. In prosthetized patients BMD of the femur and of the ischium on the side operated on is significantly less than on the contralateral one (Student's "t" test: p < 0.001). In patients with stable prostheses, BMD of the femur operated on is greater than that in females with prosthetic stem loosening (Student's "t" test: p < 0.000). Based on a comparison between these two groups we did not observe any other significant differences in BMD among the ROI analyzed. BMD was correlated with the amount of time since surgery only in the ROIs in prosthetized femurs. The study confirms the significant bone resorption of the cortex in prosthetized femurs and documents analogously significant reduction in BMD in the ischium on the side operated on. Finally, it indicates that prosthetic stem loosening may be associated with loss of BMD in the femoral cortex which is significantly greater than that observed, during analogous periods of time in stable implants.     

Correlations of new markers of bone formation and resorption in kidney transplant recipients

Renal osteodystrophy is a common complication of chronic renal failure and renal replacement therapy. Successful kidney transplantation reverses many of these abnormalities, but the improvement is often incomplete. The evaluation of renal osteodystrophy in everyday practice is based on noninvasive measurements. Taking this into consideration the aim of the present study was to assess new markers of bone metabolism: serum CrossLaps degradation products of C-terminal telopeptides of type I collagen tartrate-resistant acid phosphatase (TRAP) and bone-specific alkaline phosphatase (bALP), as well as their correlations with bone mineral disease (BMD) in kidney transplant recipients. Twenty-six patients (aged 26 to 54 years) receiving a triple immunosuppressive regimen with stable graft function were enrolled in the study. Serum parathormone (PTH) osteocalcin type collagen C-terminal peptides (ICTP), and procollagen type I carboxyterminal extension peptide (PICP) concentrations were measured by radioimmunoassay (RIA), Serum CrossLaps, bALP, beta2-microglobulin, TRAP 5b by enzyme-linked immunoassay (ELISA), and deoxypyridinoline (DPD) in urine immunochemiluminescence. BMD, as measured by dual-energy X-ray absorptiometry (DEXA), correlated negatively with markers of bone formation (bALP, osteoclacin, and PICP) and resorption (TRAP, ICTP, and beta2-microglobulin). The only positive correlation was between urine DPD and BMD at the femoral neck. Interestingly, BMD correlated negatively with CsA concentration. TRAP 5b correlated positively with serum creatinine, ALP, bALP, osteocalcin, iPTH, ICTP, and serum beta2-microglobulin, and negatively with CsA concentration, and azathioprine and prednisone dose. DPD did not correlate with any parameters. Serum CrossLaps correlated with markers of both bone formation and resorption. Because TRAP and serum CrossLaps correlated with markers of both bone formation and or resorption, additional studies are needed to establish the value of these markers of bone resorption to assess renal osteodystrophy.     

Flurbiprofen inhibits heterotopic bone formation in total hip arthroplasty

Summary A double-blind prospective parallel group study comparing slow-release flurbiprofen with placebo in the control of ectopic bone formation was carried out in 68 patients undergoing total hip arthroplasty. Eight weeks after surgery there was evidence, significant at the 1% level, that the incidence and extent of periarticular calcification was lower in the flurbiprofen group. At an early phase, serum calcium level decreased and after 8 weeks serum alkaline phosphatase level increased more in the placebo group than in the flurbiprofen group, indicating an effect of flurbiprofen on bone mineral metabolism. Six patients were withdrawn in each treatment group, four due to side effects in the flurbiprofen group and three due to side effects in the placebo group. Overall, five patients in each group reported side effects, the nature and severity of the side effects being very similar in each group. We conclude that flurbiprofen is an efficient and safe drug in limiting ectopic bone formation following total hip arthroplasty. Heterotopic bone formation is a frequent complication after total hip replacement [1, 2, 4–6, 8–16]. Heterotopic bone reduces the extent of hip motion, reduction being more evident in cases with extensive ectopic bone formation around the hip joint [3, 10, 11]. Various treatment regimens have been proposed for discouraging heterotopic bone formation. Anti-inflammatory agents such as indomethacin and ibuprofen have turned out effective [11, 12, 14]. Local irradiation also prevents ectopic bone formation [4], but diphosphonates seem not be effective in this respect [15]. The aim of the present study was to assess the efficacy of flurbiprofen, a new anti-inflammatory agent, in limiting heterotopic bone formation, and to note the frequency and severity of any side effects of the treatment.     

Fate of bone grafting for acetabular defects in total hip replacement

Background:

The use of allografts and autografts in the management of acetabular defects have been reported with varying results. Trabecular metal is an expensive option in the management of these defects. This study aims to assess the fate and efficacy of bone grafting for acetabular bone defects in total hip arthroplasty.

Materials and Methods:

A total of 30 hips in 28 patients with acetabular deficiencies were treated with bone grafting and total hip replacement (THR). Seventeen hips had American Academy of Orthopedic Surgeons (AAOS) type 2 (Paprosky type 2c) deficiency and 13 had AAOS type 3 (Paprosky type 3a) defects of the acetabulum. Allografts were used in 15 patients and autografts were used in the remaining 13. Cemented total hip arthroplasty was done in 18 hips and uncemented THR in 12. Seven patients underwent the procedure for, acetabular erosion and symptoms following hemiarthroplasty (4 out of 7), or, acetabular revision for failure (3 out of 7) following total hip arthroplasty. Acetabular deficiencies in other patients were due to posttraumatic causes, advanced primary hip arthritis and second stage treatment of postinfective arthritis. A mesh was used in 6 hips and screws were used in 13 hips for graft fixation.

Results:

Patients were followed up clinicoradiologically for a period of 10 months to 4 years (mean 23.4 months). One patient required staged revision due to infection. Two patients had early asymptomatic cup migration. One patient had graft lysis and change in cup inclination with persistent pain. He was not keen on further intervention at last followup. Other patients were pain free at the time of followup with radiographs showing maintenance of graft and implant position.

Conclusion:

Bone grafting is a suitable option in the management of acetabular defects in total hip arthroplasty, especially in resource challenged countries.     

计算机辅助术前计划在全髋关节置换术中的应用

目的 探讨计算机辅助术前计划在全髋关节置换术中的优越性.方法 2002年3月至2005年9月共筛选182例患者(208髋)参加本研究,随机分为两组,分别采用德国Preop PlanTM计算机辅助术前计划系统及常规模板测量的方法进行全髋关节置换术术前计划,对比分析术后髋臼旋转中心的偏移量、两侧外展力臂差值及双下肢长度差值.所有患者平均随访时间3个月.结果 与常规模板测量法相比,计算机辅助术前计划髋臼旋转中心的偏移量小、两侧外展力臂及下肢长度更接近平衡.结论 计算机辅助术前计划提高了全髋关节置换术的精确度,更符合生物力学和生理学要求,具有推广价值.     

Endoscopic total hip replacement in conditions of acetabulum bone structures deficiency

76 patients with acetabulum defects of posttraumatic, oncologic, displastic or systemic character, as wall as due to complications after previous hip replacement, were operated on. The author's non-tensioned acetabular component installation technique worked out for the endoscopic total hip replacement was used. Long-term follow-up results were considered to be successful in 88.6% of cases. Maximal follow-up period is 10 years.     

Implant survival and radiographic outcome of total hip replacement in patients less than 20 years old

Background and purpose — Total hip replacement (THR) is not recommended for children and very young teenagers because early and repetitive revisions are likely. We investigated the clinical and radiographic outcomes of THR performed in children and teenage patients.

Patients and methods — We included 111 patients (132 hips) who underwent THR before 20 years of age. They were identified in the Norwegian Arthroplasty Register, together with information on the primary diagnosis, types of implants, and any revisions that required implant change. Radiographs and Harris hip score (HHS) were also evaluated.

Results — The mean age at primary THR was 17 (11–19) years and the mean follow-up time was 14 (3–26) years. The 10-year survival rate after primary THR (with the endpoint being any revision) was 70%. 39 patients had at least 1 revision and 16 patients had 2 or more revisions. In the latest radiographs, osteolysis and atrophy were observed in 19% and 27% of the acetabulae and 21% and 62% of the femurs, respectively. The mean HHS at the final follow-up was 83 (15–100).

Interpretation — The clinical score after THR in these young patients was acceptable, but many revisions had been performed. However, young patients with developmental dysplasia of the hip had lower implant survival. Moreover, the bone stock in these patients was poor, which could complicate future revisions.