Less obvious risks after limb injury: osteopaenia after fracture (and in ventilated ITU patients)…

Bo E. R. Nilsson (1966) Post-Traumatic Osteopenia: A Quantitative Study of the Bone Mineral Mass in the Femur Following Fracture of the Tibia in Man Using Americium-241 as a Photon Source, Acta Orthopaedica Scandinavica, 37:sup91, 1-55, DOI: 10.3109/ort.1966.37.suppl-91.01. Measured post-traumatic osteopenia using bone densitometry. n= 41 males, 49 females. Bone loss was measured in the femoral condyles of the tibial fracture limb, and measured at approximately 25% expressed as a percentage of the non-fractured side. If there was osteomyelitis, secondary surgery, or additional injuries, the bone mineral loss could go as high as 40%. There was no relationship between the amount of bone loss measured and elapsed time since injury in females; in males the difference between sides decreases for 6-7 years, then remains static. Children who sustained their tibial fracture at/before age 11, had no residual bone loss later. Teenagers do not differ significantly from adults in respect of bone loss.

1979, Andersson & Nilsson, ‘Post-Traumatic Bone Mineral Loss in Tibial Shaft Fractures Treated with a Weight-Bearing Brace’, Acta Orthopaedica Scandinavica, 50:6, 689-691, DOI: 10.3109/17453677908991294 To link to this article: https://doi.org/10.3109/17453677908991294.

n= 27. The bone mineral content was measured in the upper tibia of patients with tibial shaft fracture. The loss of bone mineral content associated with the fracture was not affected by whether the patient was weight bearing in a functional brace, or non-weight-bearing in a long leg cast.

1987. Finsen & Haave. Acta Orthop. Scand. 58,369-371, 1987. ‘Changes in bone-mass after tibial shaft fracture’.

‘We studied 20 patients who had suffered tibial shaft fractures 30 months previously. The bone-mineral content in diaphyseal and metaphyseal bone of the femur and tibia was determined by photon absorptiometry. There was a moderate, but significant, deficit of bone-mineral in metaphyseal bone at the knee and distal tibia. This loss was, however, far smaller than that previously reported. Persisting bone-mineral changes in diaphyseal bone were insignificant except in the fracture area where there was a 28 per cent increase. This may indicate that bone may. under some circumstances, locally increase in strength after remodelling of the fracture’.

Finsen, Haave, Benum, 1989. ‘Fracture interaction in the extremities, The possible relevance of posttraumatic osteopenia’. Clinical Orthopaedics and Related Research, 01 Mar 1989, (240):244-249 PMID: 2917440 

Regional osteopenia may persist after certain types of fractures. To investigate the practical importance of this observation, the authors studied 2744 past fractures in 1659 patients with present fractures. Radial fractures rarely occurred ipsilateral to previous radial fractures, whereas fractures of the hand were more often ipsilateral to previous hand fractures. Hip fractures rarely recurred in the same hips. Patients with previous cervical hip fractures, unlike those with previous trochanteric fractures, had a predominance of subsequent fractures distal to the hip ipsilaterally. Those with previous femoral shaft fractures were more likely to have subsequent fractures ipsilaterally. Both femoral shaft and patellar fractures were more often seen on the side of previous lower extremity fractures. Patients with previous tibial fractures had more subsequent fractures of the femur and tibia ipsilaterally, and their present tibial fractures were more frequently ipsilateral when these fracture types had occurred in the past. Some of these shifts from the equal distribution of fractures between the two sides may be due to posttraumatic osteopenia.

1993. Karlsson, Nilsson, & Obrant. ‘Bone mineral loss after lower extremity trauma. 62 cases followed for 15-38 years’ Acta Orthop Scand 1993; 64 (3):3 62-364.

n=62. Patients, ….’who had been treated at our department for tibial shaft fracture (n 38) or knee ligament injury (n 24) 15-38 years earlier, were re-evaluated for post-traumatic osteopenia. 62 age- and sex matched subjects without fracture served as controls. By means of a Lunar DEXA apparatus we measured the bone mineral density (BMD) in the total body, the hips and special regions of interest (ROI) in the lower extremities. We found a difference in the BMD between the injured and uninjured legs, most obvious in the femur condyle. Measurements of bone mineral loss early after the injury did not correlate with the present late measurements. The former fracture patients had at the time of follow-up the same BMD in the rest of their bodies as a whole, compared with controls.

We conclude that post-traumatic osteopenia is still evident in the injured leg decades after the injury’.

1995. Eyres & Kanis. J Bone Joint Surg [Br] 1995:77-B:473-8. ‘Bone Loss after Tibial Fracture’.

n=5, prospectively studied with dual-energy X-ray absorptiometry (DEXA). Also 21 adults and 10 children studied at least 5 years after fracture, comparing against uninjured limb and against 10 control subjects. There was a significant loss in bone mineral density evident at 1 month, fell to 50% of normal at 3 months and persisted at 6 months. No significant improvement was seen with weight-bearing. They said:

‘Review at 5 to 11 years after adult midshaft fractures showed persistent bone loss in the distal tibia (46.5 ± 9.8% of control values), but persisting sclerosis at old fracture sites (172 ± 38% of control values). In contrast, we found no significant differences in BMD between the injured and control limb after fractures sustained in childhood either at the fracture site or in the distal segment.

We conclude that, in adults, tibial fractures are associated with definite and persistent post-traumatic loss of distal BMD.’

1997. Jarvinen & Kannus, Current Concepts Review. JBJS, Vol 79-A, No 2, February 1997, 263-276. ’Injury of an Extremity as a Risk Factor for the Development of Osteoporosis’.

Comment: The above Current Concepts Review is highly recommended as a summary of research in the field to that date.

This review identifies that a fracture of a limb is a risk factor for a subsequent fracture in that limb. However it should be noted that the literature is somewhat conflicting on this point, at least on whether this is a significant effect. 

As always, if interested in pursuing this point, go to the original papers. The reference list in this review is comprehensive and is a good starting point before more recent papers are sought out.

2000, Fox et al. ‘Loss of Bone Density and Lean Body Mass after Hip Fracture’, Osteoporosis International Volume 11, 31–35(2000). 

‘Few studies of bone loss have assessed the amount of loss directly after a hip fracture. The present prospective study was conducted to determine changes in bone mineral density (BMD) and muscle mass shortly after fracture and through 1 year to assess short-term loss and related factors. The setting was two acute care teaching hospitals in Baltimore, Maryland, and subjects were 205 community-dwelling women with a new fracture of the proximal femur between 1992 and 1995. Bone density of the nonfractured hip and whole-body and body composition were measured by dual-energy X-ray absorptiometry at 3 and 10 days and 2, 6 and 12 months after admission. Mean BMD of the femoral neck was 0.546 ± 0.007 g/cm2 at baseline. Average loss of femoral neck BMD from baseline was 2.1% at 2 months, 2.5% at 6 months and 4.6% at 12 months. The average loss of BMD in the intertrochanteric region was 2.1% at 12 months. Total lean body mass decreased by 6% while fat mass increased by 3.6% by 1 year after the fracture. These findings indicate that significant loss in BMD and lean body mass occur shortly after hip fracture while body fat increases. Continued loss was evident throughout the 1 year of follow-up. This loss of both bone density and muscle mass may lead to new fractures’.

2016, Orford et al. ‘Changes in Bone Mineral Density in the Year after Critical Illness’, American Journal of Respiratory and Critical Care Medicine Volume 193 Number 7 | April 1 2016, 736-744.

n=66.  BMD decreased significantly in the year after critical illness at both femoral neck and anterior–posterior spine sites. The annual decrease was significantly greater in the ICU cohort compared with matched control subjects (anterior–posterior spine, 21.59%; 95% confidence interval, 22.18 to 21.01; P , 0.001; femoral neck, 21.20%; 95% confidence interval, 21.69 to 20.70; P , 0.001). There was a significant increase in 10-year fracture risk for major fractures (4.85 6 5.25 vs. 5.50 6 5.52; P , 0.001) and hip fractures (1.57 6 2.40 vs. 1.79 6 2.69; P = 0.001). The pattern of bone resorption markers was consistent with accelerated bone turnover. Conclusions: Critically ill individuals experience a significantly greater decrease in BMD in the year after admission compared with population-based control subjects. Their bone turnover biomarker pattern is consistent with an increased rate of bone loss.

2018, Hopkins et al. ‘Disuse osteopenia following leg fracture in postmenopausal women: Implications for HIP fracture risk and fracture liaison services’. Radiography 24 (2018) 151-158.

‘Disuse osteopenia is a known consequence of reduced weight-bearing and has been demonstrated at the hip following leg injury but has not been specifically studied in postmenopausal women. Method: Bilateral DXA (GE Lunar Prodigy) bone mineral density (BMD) measurements were taken at the neck of femur (NOF), total hip region (TH) and lumbar spine in postmenopausal female groups comprising controls (N ¼ 43), new leg fractures (#<3wks) (N ¼ 9), and participants who had sustained a leg fracture more than one year previously (#>1yr) (N ¼ 24). #>1yr were assessed at a single visit and the remaining groups at intervals over twelve months. Weight-bearing, function, 3-day pedometer readings, and pain levels were also recorded. Results: The #<3wks demonstrated significant (p < 0.05) losses in ipsilateral TH BMD at 6 weeks from baseline 0.927 ± 0.137 g/cm2 , to 0.916 ± 0.151 g/cm2 improving to 0.946 ± 0.135 g/cm2 (n.s) at 12 months following gradual return to normal function and weight-bearing activity. The #>1yr scored significantly below controls in almost all key physical and functional outcomes demonstrating a long-term deficit in hip bone density on the ipsilateral side. Conclusion: The clinical significance of post-fracture reduction in hip BMD is a potential increased risk of hip fracture for a variable period that may be mitigated after return to normal function and weightbearing. Improvement at 12 months in #<3wks is not consistent with #>1yr results indicating that long-term impairment in function and bone health may persist for some leg fracture patients. Unilateral bone loss could have implications for Fracture Liaison Services when assessing the requirement for medication post fracture.’

Overall comment: The papers quoted above indicate that there is a loss of bone mineral density elsewhere in the injured limb of individuals over 11 years of age.  This is in the order of 25-40%. This may last for several decades. It cannot be prevented entirely by early weight bearing, but it is likely that the effect will be minimized if early return to function is achieved. 

There may be an increase in bone density in the immediate vicinity of the fracture (due to sclerosis & callus formation). 

Critical illness and mechanical  ventilation in an ITU is associated with loss of bone mineral density, in the order of 20%. This is sufficient to predict an increase in fracture risk.

In postmenopausal women, leg fractures result in a loss of bone mineral density at the ipsilateral femoral neck that is long-term, and may increase subsequent hip fracture risk.

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