Tactile/kinesthetic stimulation (TKS) increases tibial speed of sound and urinary osteocalcin (U-MidOC and unOC) in premature infants (29-32weeks PMA)

Abstract

Preterm delivery (<37 weeks post-menstrual age) is associated with suboptimal bone mass. We hypothesized that tactile/kinesthetic stimulation (TKS), a form of infant massage that incorporates kinesthetic movement, would increase bone strength and markers of bone accretion in preterm infants. Preterm, AGA infants (29-32 weeks) were randomly assigned to TKS (N=20) or Control (N=20). Twice daily TKS was provided 6 days per week for 2 weeks. Control infants received the same care without TKS treatment. Treatment was masked to parents, health care providers, and study personnel. Baseline and week two measures were collected for tibial speed of sound (tSOS, m/sec), a surrogate for bone strength, by quantitative ultrasound (Sunlight8000) and urine markers of bone metabolism, pyridinium crosslinks and osteocalcin (U-MidOC and unOC). Infant characteristics at birth and study entry as well as energy/nutrient intake were similar between TKS and Control. TKS intervention attenuated the decrease in tSOS observed in Control infants (p<0.05). Urinary pyridinium crosslinks decreased over time in both TKS and CTL (p<0.005). TKS infants experienced greater increases in urinary osteocalcin (U-MidOC, p<0.001 and unOC, p<0.05). We conclude that TKS improves bone strength in premature infants by attenuating the decrease that normally follows preterm birth. Further, biomarkers of bone metabolism suggest a modification in bone turnover in TKS infants in favor of bone accretion. Taken together, we speculate that TKS improves bone mineralization.

Figure 1. Tibial speed of sound (tSOS)

During the study period, tSOS decreased in control infants. The tSOS of TKS and Control (CTL) was significantly different by week 2. (*p<0.05)

Figure 2. Dpd/Pyd Ratio

Control (CTL) and TKS infants decreased Dpd/Pyd ratio over the study period. (Mean ± SD)

Figure 3. Urinary osteocalcin midfragments (U-MidOC)

TKS increased U-MidOC from baseline to week 2 and had a significantly higher level at week 2 compared to control (CTL). Mean ± SD

Figure 4. Urinary undercarboxylated osteocalcin (unOC)

TKS infants had increased unOC from baseline to week 2. Mean ± SD