Research Advances of Human Homologue of Mouse Progressive Ankylosis Protein and Bone and Joint Diseases / 中国医学科学院学报

The human homologue of mouse progressive ankylosis protein(ANKH)is an inorganic pyrophosphate transport regulator,which regulates tissue mineralization by controlling the level of inorganic pyrophosphate.It plays an important role in the pathogenesis and development of bone and joint diseases,such as ankylosing spondylitis,craniometaphyseal dysplasia,and articular cartilage calcification.This review summarizes the progress of research on ANKH and the above-mentioned diseases.

Iliopectineal Bursitis Associated With Calcium Pyrophosphate Crystal Deposition Disease: A Case Report / 日本農村医学会雑誌

A 93-year-old man with a history of calcium pyrophosphate deposition disease (CPPD) in the right shoulder and wrist had severe pain in his right lower limb in the absence of trauma. He was transported by ambulance to our hospital. He was febrile (38℃) and swelling of the inguinal region was noted on physical examination. Laboratory examination showed elevated C-reactive protein (19.1 mg/dL, normal range ＜ 0.3 mg/dL) and white blood cell count (9600/μl, normal range ＜ 9000/μL). X-ray showed calcifications near the hip bilaterally, computed tomography showed distension of the iliopectineal bursa, and magnetic resonance imaging showed a cystic lesion of the iliopectineal bursa. Aspiration was performed under ultrasound guidance. Fluid analysis under an optical microscope revealed calcium pyrophosphate crystals. Bacterial examination was negative. Iliopectineal bursitis associated with CPPD was diagnosed, and he was treated conservatively with NSAIDs. To our knowledge, only 5 cases of iliopectineal bursitis associated with CPPD have been reported in Japan, and here we present the details of this rare case.

Prominent Inflammatory Features of Monocytes/Macrophages in Acute Calcium Pyrophosphate Crystal Arthritis: a Comparison with Acute Gouty Arthritis

Calcium pyrophosphate (CPP) crystals can present as acute inflammatory arthritis which is known as an acute CPP crystal arthritis. Although monocytes/macrophages have been shown to play a role in the initiation of crystal-mediated inflammatory responses, differences in their phenotypes between acute CPP crystal arthritis and acute gouty arthritis have not yet been investigated. We examined the immunological characteristics of synovial monocytes/macrophages in patients with acute CPP crystal and acute gouty arthritis. CD14⁺CD3⁻CD19⁻CD56⁻ cell frequencies in synovial fluid mononuclear cells (SFMCs) were measured. Expression of pro- and anti-inflammatory cytokines and markers was determined. The SFMCs were dominated by a population of monocytes/macrophages in acute CPP crystal arthritis similar to that in acute gout. Synovial monocytes/macrophages showed the phenotypes of infiltrated monocytes as shown by expression of CD88, C-C chemokine receptor type 2, myeloid-related protein (MRP)8 and MRP14 but not proto-oncogene tyrosine-protein kinase MER. Comparatively, the CD14⁺ cells from patients with acute CPP crystal arthritis had similar high levels of IL-1β and TNF-α production but significantly lower expression of IL-10 and M2 marker (CD163). The monocytes/macrophages had the capacity to produce IL-8 in response to CPP crystals. Proinflammatory features were more dominant in monocytes/macrophages during acute CPP crystal arthritis than those during acute gouty arthritis.

The Role of Calcium Pyrophosphate Dihydrate Deposition in the Postoperative Outcome of Lumbar Spinal Stenosis Patients

STUDY DESIGN: Retrospective study.PURPOSE: This study aimed to investigate the association of surgical intervention with clinical and quality of life (QoL) outcomes in patients who underwent posterior spinal surgery for lumbar spinal stenosis (LSS) with spinal calcium pyrophosphate dihydrate deposition (SCPPD) versus that in those who underwent the surgery for LSS without SCPPD.OVERVIEW OF LITERATURE: Calcium pyrophosphate (CPP)-associated arthritis is one of the most common types of arthritis. The clinical outcomes are well studied in CPP-associated arthritis of the appendicular joints. However, few studies have investigated SCPPD.METHODS: A single-institution database was reviewed. LSS patients were categorized as those who did and did not have SCPPD, based on histologic identification. Clinical presentations and postoperative results were analyzed. Disability and QoL were assessed using the Oswestry Disability Index (ODI) and the 36-item Short-Form Health Survey.RESULTS: Thirty-four patients were enrolled, with 18 patients being allocated to the SCPPD group and 16 being allocated to the non- SCPPD group. Preoperative and postoperative pain scores were not significantly different between the groups (p=0.33 and p=0.48, respectively). The average preoperative ODI score in the SCPPD group was slightly higher than that in the non-SCPPD group (57 vs. 51, p=0.33); however, the postoperative ODI score was significantly lower (15 vs. 43, p=0.01). The postoperative physical function, vitality, and mental health of the SCPPD patients were also significantly improved (p=0.03, p=0.022, and p=0.022, respectively).CONCLUSIONS: Surgical intervention resulted in good clinical outcomes in SCPPD patients. As per our findings, total removal of CPPinvolved tissue is unnecessary. As such, surgery should be performed as indicated according to clinical presentation without considering the presence of CPPD.

Calcium pyrophosphate dihydrate deposition disease in the temporomandibular joint: diagnosis and treatment / 대한악안면성형재건외과학회지

BACKGROUND: Calcium pyrophosphate dihydrate deposition disease (CPDD) is a rare disease in the temporomandibular joint (TMJ) space. It forms a calcified crystal mass and induces a limitation of joint movement. CASE PRESENTATION: The calcified mass in our case was occupied in the left TMJ area and extended to the infratemporal and middle cranial fossa. For a complete excision of this mass, we performed a vertical ramus osteotomy and resected the mass around the mandibular condyle. The calcified mass in the infratemporal fossa was carefully excised, and the segmented mandible was anatomically repositioned. Scanning electronic microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) microanalysis was performed to evaluate the calcified mass. The result of SEM/EDS showed that the crystal mass was completely composed of calcium pyrophosphate dihydrate. This result strongly suggested that the calcified mass was CPDD in the TMJ area. CONCLUSIONS: CPDD in the TMJ is a rare disease and is difficult to differentially diagnose from other neoplasms. A histological examination and quantitative microanalysis are required to confirm the diagnosis. In our patient, CPDD in the TMJ was successfully removed via the extracorporeal approach. SEM/EDS microanalysis was used for the differential diagnosis.

Age-Related Prevalence of Periodontoid Calcification and Its Associations with Acute Cervical Pain

STUDY DESIGN: Prospective study. PURPOSE: To assess the prevalence of periodontoid calcification and its associations with acute cervical pain. OVERVIEW OF LITERATURE: Calcium pyrophosphate dihydrate (CPPD) deposition disease is a common rheumatological disorder that occurs especially in elderly patients. Although CPPD crystals induce acute arthritis, these crystals are not usually symptomatic. Calcification surrounding the odontoid process (periodontoid calcification) has been reported to induce inflammation, resulting in acute neck pain. This disease is called crowned dens syndrome. Whether calcification induces inflammation or whether the crystals are symptomatic remains unclear. METHODS: The prevalence of periodontoid calcification at the atlas transverse ligament was examined by computed tomography of the upper cervical spine in patients suspected of brain disease but no cervical pain (control group, n=296), patients with pseudogout of the peripheral joints but no cervical pain (arthritis group, n=41), and patients with acute neck pain (neck pain group, n=22). Next, the correlation between the prevalence of periodontoid calcification and symptoms was analyzed. RESULTS: In the control group, 40 patients (13.5%) showed periodontoid calcification with no significant difference in the prevalence with gender. The prevalence of calcification increased significantly with age (p=0.002). In the arthritis group, 26 patients (63.4%) reported periodontoid calcification. In the neck pain group, 14 patients (63.6%) reported periodontoid calcification. Multiple logistic regression analysis by age and group revealed that higher age, inclusion in the arthritis group, and inclusion in the neck pain group significantly affected the prevalence of calcification. CONCLUSIONS: Our results cumulatively suggest that periodontoid calcification is an aging-related reaction and that calcification per se does not always cause neck pain. Periodontoid calcification was observed more frequently in patients with pseudogout of the peripheral joints and in those with acute neck pain than in asymptomatic control patients.

Revisión sistemática de la literatura sobre el tratamiento con colchicina en pacientes adultos con osteoartritis de rodilla / Colchicine treatment in adult patients with knee osteoarthritis: Systematic review of the literature

Resumen Contexto: En la práctica clínica de muchos reumatólogos y en algunos ensayos clínicos se ha usado colchicina en pacientes con osteoartritis primaria. A pesar de ello, su papel en el tratamiento de la misma no está claro y las guías no establecen recomendaciones al respecto. Objetivos: Evaluar la eficacia y la seguridad del tratamiento con colchicina en pacientes adultos con osteoartritis de rodilla, tanto primaria como asociada al depósito de cristales de pirofosfato cálcico. Métodos: Se llevó a cabo una búsqueda estructurada de la literatura utilizando las bases de datos Pubmed, Embase, Cochrane Controlled Trials Register y LILACS. Se incluyeron ensayos clínicos controlados, aleatorizados, en donde se haya usado colchicina como intervención en pacientes adultos con osteoartritis de rodilla, primaria o relacionada con pirofosfato de calcio. Resultados: Se incluyeron 5 ensayos clínicos controlados. Se observó una tendencia común en todos los estimados puntuales de los artículos a favorecer el uso de la colchicina para la mejoría del dolor y de la funcionalidad. Se observó una mayor tendencia de efectos adversos gastrointestinales con el uso de la colchicina, sin embargo, el efecto no fue estadísticamente significativo en los estudios individuales. Ninguno de los estudios evaluó calidad de vida. Conclusiones: La colchicina parece ser una alternativa eficaz y segura para el tratamiento de pacientes adultos con osteoartritis de rodilla, tanto primaria como asociada al depósito de cristales de pirofosfato de calcio. Su uso reduce el dolor y mejora la funcionalidad, aunque puede producir síntomas gastrointestinales en algunos pacientes.

Abstract Background: Colchicine is often used in patients with osteoarthritis in which calcium pyrophosphate crystal deposition disease is suspected. Colchicine has also been used by many rheumatologists in clinical practice, and in some trials, on patients with primary osteoarthritis (apparently unrelated to calcium pyrophosphate). However, its role in the treatment of primary osteoarthritis is not clear, and international guidelines have not established recommendations. Objective: To evaluate the efficacy and safety of colchicine for the treatment of adult patients with primary knee osteoarthritis as well as the form associated with calcium pyrophosphate. Methods: A structured literature search was conducted using the PubMed, Embase, Cochrane Controlled Trials Register, and LILACS databases. Randomised controlled trials were included in which colchicine was used as intervention in patients with primary or pyrophosphate calcium-associated knee osteoarthritis. Results: The study included 5 randomised controlled trials, all of which showed a common trend in all estimated points of the joint, favouring the use of colchicine for improvement in pain and functionality. Although the effect was not statistically significant in individual studies, there was a greater tendency of gastrointestinal adverse effects with the use of colchicine. None of the studies assessed quality of life. Conclusions: Colchicine appears to be an effective and safe alternative for treatment of adult patients with knee osteoarthritis, either primary or associated with the deposit of calcium pyrophosphate crystals. Its use reduces pain and improves functionality, but it can cause gastrointestinal symptoms in some patients.

Clinical characteristics and medical imaging analysis of 20 cases with calcium pyrophosphate deposition / 中华风湿病学杂志

Objective To investigate the clinical and imaging features of patients with calcium pyrophosphate deposition (CPPD).Methods The clinical data and X-rays material of knee joint of 20 patients with CPPD were retrospectively analyzed.Pearson/Spearman's correlations analysis was used for statistical analysis with software version 15.0.Results The 20 patients with CPPD had demonstrated that the typical accumulation of calcium,which accounted for about 1.5％o(20/13 536) among patients over 55 years old who had knees X-ray at the same period in Chaoyang Hospital.Female patients of CPPD was 80％ (16/20).Seventeen patients completed follow-up visits.The age of onset for CPPD ranged from 44 to 85 years old,the percentage of CPPD patients over 70 years old was 71％(12/17).Among the 17 cases of followed,14 cases (82％) were patients with paroxysmal arthritis with the initial site of knee joint (79％) and ankle joint (21％).Most patients suffered from moderate to severe pain,while some might have local congestion and increased skin temperature.Five patients had more than two different joints attacked by arthritis.The distribution of the affected areas was knee,ankle,hip,elbow,wrist and metacarpophalangeal joints.The median number of attack was 1.5 times a year,and the median duration of attack was 8.5 days.Among the 14 patients,Six cases of them had no recurrence after treatment,but six cases had recurrent attacks within a year.The imaging of lateral articular facet showed that calcium deposit was extended and thickness of calcification was increased.Plus osteophyte formation stage was 100％ with an average of 3.0±1.6 and 85％ sclerosis of articular facet.The rate of attacks of arthritis had a positive correlation with calcium deposition range of lateral articular facet (r=0.663,P=0.010) and a negative correlation with sclerosis of articular facet (r=-0.548,P=0.042).Conclusion Old patients with paroxysmal joint pain,patients with knee joint or other big joints as the initial joints involved,patients with long duration disease,patients who had more than two joints at attack and patients with calcium deposition in imaging,should be suspected for CPPD clinically.Moreover,patients with a wide range of calcium deposition are high likely to suffer from recurrent arthritis attack.

A Case of Acute Calcium Pyrophosphate Crystal Arthritis in the Lumbar Facet Joint

Calcium pyrophosphate dihydrate deposition disease most commonly presents with acute arthritis of the peripheral joints. Infrequently, a mass effect of this disease can cause axial symptoms, such as spinal stenosis, radiculopathy, or myelopathy. Herein, we report on the first Korean case of acute arthritis in the lumbar facet joint due to calcium pyrophosphate dihydrate crystal deposition disease. A 73-year-old female presented with acute fever, severe lumbago, and knee arthralgia, 11 days after partial parathyroidectomy. Plain radiographs showed multiple chondrocalcinosis, while a bone scan, computed tomography, and magnetic resonance imaging showed right L5-S1 facet arthritis. In synovial fluid from the facet and knee joints, positively birefringent calcium pyrophosphate dihydrate crystals were observed under polarized light microscopy. Under the diagnosis of acute calcium pyrophosphate dihydrate crystal arthritis (formerly known as 'pseudogout') in the facet joint, an intra-articular triamcinolone injection was administered, which resulted in dramatic improvement of the symptoms within 24 hours.

Ultrasonographic Assessment in Crystal-induced Arthritis / 대한내과학회지

The latest recommendations for the diagnosis and management of crystal-induced arthritis, such as gout and calcium pyrophosphate dihydrate (CPPD) deposition disease, recognize the diagnostic potential of musculoskeletal ultrasonography (MSUS). MSUS allows rapid, highly sensitive, non-invasive detection of microcrystal aggregates in multiple anatomic areas, and can be used as a safe, reliable guide for aspiration of articular and periarticular specimens suitable for microscopic analysis. MSUS can also be used to monitor disease after treatment. Ultrasonographic differentiation between gout and CPPD deposition disease is based on the characteristics of crystal aggregates and their preferential localization in different anatomical areas. This rapid assessment may profoundly affect the clinical process, avoiding expensive, time-consuming diagnostic procedures. This article reviews the current status of and recent advances in MSUS imaging in crystal-induced arthritis.

Crowned Dens Syndrome: A Case Report and Review of the Literature

The crowned dens syndrome (CDS), also known as periodontoid calcium pyrophosphate dehydrate crystal deposition disease, is typified clinically by severe cervical pain, neck stiffness and atlantoaxial synovial calcification which could be misdiagnosed as meningitis, epidural abscess, polymyalgia rheumatica, giant cell arthritis, rheumatoid arthritis, cervical spondylitis or metastatic spinal tumor. Crystalline deposition on cervical vertebrae is less well known disease entity and only a limited number of cases have been reported to date. Authors report a case of CDS and describe the clinical feature.

A Case of Calcium Pyrophosphate Dihydrate Deposition Disease Associated with Primary Hyperparathyroidism

Calcium pyrophosphate dihydrate (CPPD) deposition disease is a heterogeneous group of diseases with CPPD crystal deposition. Aging is the most common risk factor for CPPD deposition, followed by osteoarthritis and previous injury. Occasionally, CPPD depositions are associated with familial predisposition and metabolic diseases, including hemochromatosis, primary hyperparathyroidism, hypophosphatasia, and hypomagnesemia. CPPD deposition diseases associated with primary hyperparathyroidism in Koreans have rarely been reported. Thus, we report a case of a relatively young female patient with CPPD deposition disease associated with primary hyperparathyroidism, which was diagnosed through a polarized microscopic examination of the synovial fluid and a subtotal parathyroidectomy.

Cauda Equina Syndrome Caused by Pseudogout Involving the Lumbar Intervertebral Disc

Calcium pyrophosphate dihydrate (CPPD) deposition disease, also known as pseudogout, is a disease that causes inflammatory arthropathy in peripheral joints, however, symptomatic involvement of the intervertebral disc is uncommon. Herein, we describe a 59-yr-old patient who presented with cauda equina syndrome. Magnetic resonance imaging of the patient showed an epidural mass-like lesion at the disc space of L4-L5, which was compressing the thecal sac. Biopsy of the intervertebral disc and epidural mass-like lesion was determined to be CPPD deposits. We reviewed previously reported cases of pseudogout involving the lumbar intervertebral disc and discuss the pathogenesis and treatment of the disease.

The First Clinical Trial of Beta-Calcium Pyrophosphate as a Novel Bone Graft Extender in Instrumented Posterolateral Lumbar Fusion

BACKGROUND: Porous beta-calcium pyrophosphate (beta-CPP) was developed to improve the fusion success of posterolateral lumbar fusion (PLF). The possibility of accomplishing PLF using a mixture of porous beta-CPP and iliac bone was studied. This paper reports the radiologic results of PLF using the beta-CPP plus autograft for lumbar degenerative disease as a bone graft extender. METHODS: A prospective, case-matched, radiographic study evaluating the results of short segment lumbar fusion using a beta-CPP plus autograft was performed to compare the efficacy of beta-CPP plus autograft with that of an autograft alone for short segment lumbar fusion. Thirty one consecutive patients (46 levels) underwent posterolateral fusion with pedicle screw fixation and additional posterior lumbar interbody fusion. In all patients, 3 mL of beta-CPP plus 3 mL of autogenous bone graft was placed randomly in one side of a posterolateral gutter, and 6 mL of autogenous iliac bone graft was placed on the other. The fusion rates, volumes of fusion masses, and bone absorption percentage were evaluated postoperatively using simple radiographs and 3 dimensional computed tomography (3D-CT) scans. RESULTS: The control sides treated with an autograft showed significantly better Lenke scores than the study sides treated with beta-CPP at 3 and 6 months postoperatively, but there was no difference between the two sides at 12 months. The fusion rates (confirmed by 3D-CT) were 87.0% in the beta-CPP group and 89.1% in the autograft group, which were not significantly different. The fusion mass volumes and bone absorption percentage at 12 months postoperatively were 2.49 mL (58.4%) and 1.89 mL (69.5%) for the beta-CPP and autograft groups, respectively, and mean fusion mass volume was significantly higher in the beta-CPP group. CONCLUSIONS: beta-CPP combined with an autograft is as effective as autologous bone for grafting during instrumented posterolateral spinal fusion. These findings suggest that beta-CPP bone chips can be used as a novel bone graft extender for short-segment posterolateral spinal fusion.

A Case of CPPD Crystal Deposition Disease in a Patient with Rheumatoid Arthritis and Systemic Sclerosis / 대한류마티스학회지

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease is an inflammatory arthropathy that is defined by the deposition of CPPD crystals in articular and periarticular structures. CPPD crystal deposition disease has various clinical manifestation patterns ranging from an absence of symptoms to a severely destructive arthropathy. CPPD crystal deposition disease very rare with rheumatoid arthritis or systemic sclerosis. We report a case of CPPD crystal deposition disease combined in a patient with rheumatoid arthritis and systemic sclerosis.

Idiopathic Calcium Pyrophosphate Dihydrate (CPPD) Crystal Deposition Disease in a Young Female Patient : A Case Report

PURPOSE: Calcium pyrophosphate dihydrate crystal deposition disease(CPPD) is a disease of the elderly and extremely rare in young individuals. If young people develop CPPD crystal deposition disease, it may be associated with metabolic diseases, such as hemochromatosis, hyperparathyroidism, hypophosphatasia, hypomagnesemia, Wilson's disease, hypothyroidism, and gout. MATERIALS AND METHODS: Therefore, in young-onset CPPD crystal deposition disease, an investigation of any predisposing metabolic conditions is warranted. CONCLUSION: We report a case of a young female patient who presented with idiopathic CPPD crystal deposition disease at 25 years of age.

Calcium Pyrophosphate Dihydrate Crystal Deposition Disease in the Cervical Ligamentum Flavum: A Case Report / 대한척추외과학회지

Calcium pyrophosphate dihydrate deposition disease (CPPD) is an inflammatory arthropathy that is defined by the deposition of CPPD crystals in articular and periarticular structures. The cervical ligamentum flavum is a rare location of CPPD deposition. A 65-year-old woman was admitted with complaints of neck pain and a tingling sensation and numbness below the xiphoid process for 2 months. Magnetic resonance (MR) imaging and computed tomography (CT) revealed compression of the spinal cord due to a nodular calcified mass in or attached to the ligamentum flavum at the C4-5, C5-6, or C6-7 level. The patient underwent a laminectomy at C4-5, C5-6, and C6-7, and resectioning of calcified extradural nodules that impinged on the cervical cord. The operation resulted in a resolution of neck pain and hypoesthesia, except in the feet. Histopathological examination of the excised specimen revealed rectangular CPPD crystals. Here, we report a case of compressive cervical spine due to CPPD deposition disease of the cervical spine and describe the literature relevant to CPPD deposition disease of the cervical spine.

A case of calcium pyrophosphate dihydrate deposition disease causing compressive cervical myelopathy / 대한내과학회지

Calcium pyrophosphate dihydrate (CPPD) deposition disease is an inflammatory arthropathy that is defined by the deposition of CPPD crystals in articular and periarticular structure. Spinal involvement in CPPD deposition disease is rare. We reported a rare case of CPPD deposition disease that caused compressive cervical myelopathy. A 57-year-old woman was admitted to the hospital with 1 week history of progressive paresis of the right upper and lower extremities. Computed tomography showed the round and nodular calcified ligamentum flavum. Magnetic resonance imaging showed a low intensity epidural mass pressing and distorting the cervical cord at C-4 and 5 levels on both T1 and T2- weighted images. Radiographic findings were consistent with calcification of the ligamentum flavum in the C-4 and 5 levels causing cord compression. The lesion was eventually removed by hemilaminectomy. The mass was composed of a very hard crystal like calcified deposition in the ligamentum flavum. The histopathological evaluation of the exicised ligamentum flavum revealed the characteristic crystals of CPPD.

Idiopathic Calcium Pyrophosphate Dihydrate (CPPD) Crystal Deposition Disease in a Young Male Patient: A Case Report

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease is a disease of the elderly and extremely rare in young individuals. If young people develop CPPD crystal deposition disease, it may be associated with metabolic diseases such as hemochromatosis, hyperparathyroidism, hypophosphatasia, hypomagnesemia, Wilson's disease, hypothyroidism, gout, acromegaly, and X-linked hypophosphatemic rickets. Therefore, in young-onset polyarticular CPPD crystal deposition disease, investigation for predisposing metabolic conditions is warranted. We report a case of a young male patient with idiopathic CPPD crystal deposition disease, who did not have any evidences of metabolic diseases after thorough evaluations. As far as we know, this is the first report of a young male patient presented with idiopathic CPPD crystal deposition disease.

Porous Beta-Calcium Pyrophosphate as a Bone Graft Substitute in a Canine Bone Defect Model / 대한정형외과학회잡지

PURPOSE: To evaluate the possibility of using porous beta-calcium pyrophosphate (beta-CPP) as a bone graft substitute by comparing its osteoconduction and degradation with porous hydroxyapatite (HA). MATERIALS AND METHODS: Porous HA and porous beta-CPP were implanted in the proximal tibia of 7 dogs. Two animals were sacrificed at 8weeks and 5 animals were sacrificed at 20 weeks after surgery. Radiographs and histologic sections were evaluated. RESULTS: The mean period required for the radiolucent zone to disappear was 7.1+/-1.1 weeks in HA and 6.4+/-1.1 weeks in beta-CPP. By serial radiography, resorption was more prominent in porous beta-CPP than in porous HA at 8 weeks (p=0.04) and at 20 weeks. The proportion of bony tissue in the pore was 16.8% in HA and 29.7% in -CPP. The proportion of pores with bony tissue was 70.2% in HA and 62.5% in beta-CPP at 8 weeks. CONCLUSION: In beta-CPP, the new bone growth was as vigorous as in HA, but the degradation was more rapid than in HA. These results suggest that beta-CPP is a more ideal new bone graft substitute.