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Hydroxyapatite (MCHC) Research
Too few graded studies
17 peer-reviewed studies
What the evidence says
Too few graded studies
Hydroxyapatite (MCHC) doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from medium-quality meta-analyses and randomised trials published 1985–2026 with a typical study size of 62 participants.
Based on 17 studies · 1 meta-analysis · 10 RCTs · 1,860 total participants
Confidence
High confidence
By outcome
Bone healthAgainst calcium carbonate, bone density was maintained slightly better in small trials (pooled difference about 1%). No trial measured fracture, and the one placebo-controlled trial found no significant bone density change at 6 months. · 12-36 months
Too few graded studies12 studies
Fracture healing
Mostly mechanism / observational4 studies
Pain & analgesia
Too few graded studies3 studies
Safety profile
Too few graded studies3 studies
Calcium absorption & serum calcium
Too few graded studies2 studies
Steady research
4 studies in the last 5 years · Latest meta-analysis: 2009
198520052026
1RCTCited 11×n=153 · medium study2004
In plain English: The effects on bone resorption markers or on bone mineral density did not reach statistical significance, although OHC increased bone density by 0.8% at the spine at 12 months.
Albertazzi P, et al. · Climacteric (2004)
Randomised, double-blind, placebo-controlled trial in 153 osteopenic postmenopausal women with low calcium intake: 500 mg calcium a day as OHC, 500 mg as tricalcium phosphate, or placebo.
At 3 and 6 months both calcium forms lowered bone formation markers significantly compared with placebo.
Against baseline, osteocalcin fell 12.3% with OHC and 9.9% with tricalcium phosphate at 6 months. These percentages are changes from baseline, not differences from placebo.
In plain English: The citrate-carbonate and MCH doses produced comparable decreases in bone resorption (measured as serum C-telopeptide (CTX)) over 8 h and bone turnover (CTX and procollagen type-I N-terminal propeptide) at 3 months.
Bristow SM, et al. · Br J Nutr (2014)
Randomised trial in 100 postmenopausal women (mean age 71) given 1 g calcium a day as citrate, carbonate, one of two microcrystalline hydroxyapatite preparations, or placebo, for 3 months.
Microcrystalline hydroxyapatite raised ionised calcium less than citrate or carbonate, but raised serum phosphate and the calcium-phosphate product.
Bone resorption over 8 hours and bone turnover at 3 months fell by similar amounts with microcrystalline hydroxyapatite and with conventional calcium (no between-group difference is reported in the abstract). No advantage over ordinary calcium on turnover was found.
In plain English: After 20 months of treatment the loss of trabecular bone was 0.8 +/- 0.5% in the OHC group and 1.8 +/- 0.7% in the CC group.
Rüegsegger P, et al. · Osteoporos Int (1995)
Randomised, double-masked trial in 40 women with postmenopausal osteoporosis, each given 1,400 mg calcium a day as either OHC or calcium carbonate for 20 months.
Peripheral trabecular bone, measured by high-precision peripheral quantitative CT, fell 0.8% with OHC and 1.8% with calcium carbonate, a statistically significant difference.
Both groups still lost bone. The trial measured peripheral bone density only, not fracture.
In plain English: The percent change in BMD significantly favored the OHC group (1.02% [95% CI, 0.63-1.41], P < 0.00001).
Castelo-Branco C, et al. · Menopause (2009)
Meta-analysis of randomised controlled trials comparing ossein-hydroxyapatite complex (OHC) with calcium carbonate, not with placebo. Of 18 controlled trials identified, 6 were pooled in a random-effects model, and the abstract does not give the total number of participants.
Percent change in bone mineral density favoured OHC by 1.02% (95% CI 0.63-1.41, P < 0.00001), with no significant heterogeneity, and a sensitivity analysis excluding trials without full data gave the same result.
The outcome is bone density, a surrogate. No fracture outcome was pooled, and several of the review's authors also ran trials it pooled.
In plain English: Changes in mean BMD at the lumbar spine and femoral neck between baseline and year 3 were -1.1% and 2.5% for OHC and -2.3% and 1.2% for calcium carbonate, respectively.
Ciria-Recasens M, et al. · Clin Drug Investig (2011)
Randomised, open-label trial in 120 women over 65 with osteoporosis (55 OHC, 65 calcium carbonate), of whom 54 completed 3 years. OHC gave 712 mg elemental calcium a day and calcium carbonate 1,000 mg, and both groups also took calcifediol.
Serum osteocalcin rose more with OHC than with calcium carbonate at years 2 and 3 (p < 0.05 at both).
Lumbar spine density changed -1.1% with OHC and -2.3% with calcium carbonate, femoral neck +2.5% and +1.2%. The abstract gives no test of the between-group difference in bone density, and more than half the women did not complete follow-up.
In plain English: The additional use of OHC was not associated with statistically significant improvements in functional outcomes.
Zaborska M, et al. · Pharmaceuticals (Basel) (2026)
Prospective randomised study of 62 patients with a distal radius fracture treated without surgery, 31 given OHC throughout fracture treatment and 31 not.
Grip strength, palmar and dorsal flexion strength and wrist range of motion did not differ between the OHC and control groups.
There was no placebo, and the abstract does not report blinding.
In plain English: The decrease in serum PTH observed after administration of an ossein-hydroxyapatite complex was significantly less important than after the four other calcium salts, even if statistically different than after vehicle.
Deroisy R, et al. · Clin Rheumatol (1997)
Randomised comparison in healthy male volunteers of single oral doses of a vehicle and five calcium salts prescribed in Western Europe, including an ossein-hydroxyapatite complex. The abstract does not state the number of participants or the calcium dose
Every calcium salt raised serum calcium and lowered parathyroid hormone compared with baseline and with the vehicle, and serum calcium increments did not differ significantly between salts
The fall in parathyroid hormone after the ossein-hydroxyapatite complex was significantly smaller than after the four other salts, and calcium carbonate and citrate lowered it most
In plain English: Over the study period, the mean ADSoS diminished in both groups even though the rate of reduction was higher in the RLX plus CC group, with a mean change in ADSoS score of -18.72 m/s from baseline to year 3 in the RLX plus OHC group and -63.64 m/s in the RLX+CC group (P = 0.006).
Pelayo I, et al. · Menopause (2008)
Open-label randomised trial in 90 postmenopausal women taking raloxifene, who added either OHC (n = 48) or calcium carbonate (n = 42) for up to 3 years.
Bone, measured by ultrasound speed of sound rather than DXA, declined in both groups but less with OHC (-18.72 vs -63.64 m/s at year 3, P = 0.006), with similar results on T and Z scores.
Adverse effects were infrequent and similar between groups. Ultrasound is not the standard measure for bone density, and fracture was not assessed.
In plain English: In women receiving OHC, BMD at the L2-L4 site remained stable over the 3-year follow-up period (mean [SD] change 0.00 [0.11] g/cm2).
Castelo-Branco C, et al. · Climacteric (2020)
Prospective, non-randomised, open-label comparison in 851 perimenopausal women with a T-score of -2 or above, given OHC (712 mg calcium a day) or calcium carbonate (1,000 mg calcium a day) for 3 years.
Lumbar spine density stayed stable with OHC and fell 3.1% with calcium carbonate, a significant difference favouring OHC (p < 0.001).
Adverse drug reactions, mainly gastrointestinal, were less frequent with OHC (2.7% vs 7.7%, p = 0.001).
In plain English: Two-way analysis of variance using treatment group and time as independent variables revealed a significantly greater effect of OHC over CC on VAS and VRS scores.
Castelo-Branco C, et al. · Maturitas (2015)
Randomised, open-label trial in 74 osteopenic perimenopausal women given calcium carbonate 1,200 mg a day (n = 38) or OHC 1,660 mg a day (n = 36) for 6 months.
Back and knee pain scores fell significantly with OHC after 5 and 6 months, while changes with calcium carbonate were minor and not significant. The between-group effect favoured OHC.
SF-36 physical component and vitality improved with OHC only. Pain is a subjective outcome and neither participants nor assessors were blinded.
In plain English: Both skeletal symptoms (back pain) and fractures were uncommon during the trial period but both showed non-significant differences in favour of the MCHC group and biochemical investigations were suggestive of a reduction in parathyroid over-activity.
Stellon A, et al. · Postgrad Med J (1985)
Controlled 2-year trial in 36 patients with chronic active hepatitis on long-term corticosteroids.
Back pain and fractures were uncommon, and the differences favouring microcrystalline hydroxyapatite were not statistically significant.
Radius bone mineral loss stopped in the treated group, and the fall in iliac crest cortical thickness was significantly smaller (P < 0.025). The increase in trabecular bone volume on biopsy was not significant.
In plain English: Subjects on OHC therapy did not show significant changes related to baseline on bone mass across the study, whereas a significant decrease was detected in the calcium carbonate group during the second year (-3.7%, P < .05)
Castelo-Branco C, et al. · J Reprod Med (1999)
Open study in 60 postmenopausal women who declined hormone therapy, allocated to OHC 3.32 g a day (n = 19), calcium carbonate 2.5 g a day (n = 21) or no treatment (n = 20) for 2 years.
Bone density did not change significantly from baseline with OHC, fell 3.7% in the second year with calcium carbonate, and fell 3.5% and 5.6% in the untreated group.
The comparisons reported are each group against its own baseline. The abstract does not state that allocation was randomised or report a direct test between OHC and calcium carbonate.
13ObservationalCited 3×n=60 · small study2025
In plain English: In Group 1, bone union was observed in 100% of patients, in Group 2, 93% of patients achieved bone union.
Morasiewicz P, et al. · J Clin Med (2025)
Retrospective comparison of 60 patients with aseptic tibial nonunion treated with an Ilizarov external fixator, 31 who received OHC and 29 who did not.
Bone union was reached in 100% with OHC and 93% without (p = 0.041).
Maintained union, time to fixator removal, time to pain relief, time to return to activity and complication rates did not differ significantly between groups.
In plain English: There were no differences between groups in initial limb shortening, median limb lengthening, median elongation index, median alignment index, and complication rate.
Morasiewicz P, et al. · Life (Basel) (2026)
Retrospective comparison of 95 patients undergoing lower-leg lengthening osteotomy with an Ilizarov fixator, 35 given OHC and 60 matched controls who were not.
External fixation lasted longer with OHC (median 183 vs 143 days, p = 0.014), and radiological outcomes and complication rates did not differ.
Fewer OHC patients were taking analgesics at follow-up (22.9% vs 80%, p < 0.001). The authors conclude any potential benefit should be treated with caution.
In plain English: Biochemical indices were significantly lower in the treatment group compared to the controls after the first year, but in only half the patients after three years.
Stĕpán JJ, et al. · Bone (1989)
Prospective controlled 3-year trial in 48 women who had both ovaries removed 1 to 5 years earlier, 28 treated and 20 controls. The abstract does not say that allocation was randomised
The compound provided 1.6 g calcium, 0.74 g phosphorus and 1.94 g non-collagen peptides a day
Bone turnover markers were lower than in controls after the first year, but in only half the treated women after 3 years. By year 3 these responders had a larger cortical bone area than controls
In plain English: Moreover, the use of the ossein-hydroxyapatite complex helps reduce the number of complications and shortens the time to achieve pain relief and to resume normal activities.
Morasiewicz P, et al. · Pharmaceuticals (Basel) (2024)
Retrospective comparison of 51 patients with lower-leg fractures treated with an Ilizarov fixator, 26 who received an ossein-hydroxyapatite compound and 25 who did not
Median time to bone union was 108.5 days with the compound and 134 days without (p < 0.001), and union was reached in 100% versus 96% (not significant)
Complications were fewer with the compound (30.8% vs 60%, p = 0.035), and pain relief and return to activity came sooner
In plain English: Bone mass did not change significantly, whilst it dropped significantly statistically in the controls.
Ringe JD, Keller A · Geburtshilfe Frauenheilkd (1992)
Open randomised study in 20 pregnant women on long-term heparin for thrombosis: 9 took 6.46 g of OHC a day for 6 months and 11 took no bone treatment.
Bone mass did not change significantly with OHC and fell significantly in the untreated women. Compliance was good, no side effects were reported, and back pain was reduced.
This is the only pregnancy trial cited here. It is very small, unblinded, has no active calcium comparator, and concerns a specific heparin-exposed group.