Distal radius fracture pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rohan A. Bhimani, M.B.B.S., D.N.B., M.Ch.[2]
Overview
The pattern of fracture and degree of comminution are the resultant of several factors or variables such as the nature of the fall, the bone quality, the age and weight of the patient, the energy involved, and the position of the hand and wrist at the time of impact. Various combinations of these variables lead to a variety of different fracture patterns.
Pathophysiology
- The fracture pattern and severity of comminution depends on multiple factors:
- Nature of the fall
- Bone quality
- Age of the patient
- Weight of the patient
- Energy involved
- Position of the hand and wrist at the time of impact
Mechanism of Fracture
- Most of the distal radius fractures are caused by a fall on the outstretched hand with the wrist in dorsiflexion.[1][2][3][4][5][6][7][8]
- The form and severity of fracture of distal radius as well as the concomitant injury of disco-ligamentary structures of the wrist also depend on the position of the wrist at the moment of hitting the ground.
- The width of the angle influences the localization of the fracture.
- Pronation, supination and abduction determine the direction of the force and the compression of carpus and different appearances of ligamentary injuries.
- The radius initially fails in tension on the volar aspect, with the fracture progressing dorsally where bending forces induce compressive stresses, resulting in dorsal comminution.
- As the deformation of the wrist continues, the ulnar styloid may also fracture due to the attachment of the triangular fibrocartilage complex to its base and the distal radius.
- In elderly osteoporotic patients the distal ulna may fracture through the metaphysis.
- Cancellous impaction of the metaphysis further compromises dorsal stability.
- Additional shearing forces influence the injury pattern, resulting in articular surface involvement.
- Distal radius fractures typically occur with the wrist bent back from 60 to 90 degrees.
- Radial styloid fracture would occur if the wrist is ulnar deviated and vice versa.
- If the wrist is bent back less, then proximal forearm fracture would occur, but if the bending back is more, then the carpal bones fracture would occur.
Anatomy of Articular Interface of Distal Radius
- The articular surface of the distal aspect of the radius tilts 21 degrees in the antero-posterior plane and 5 to 11 degrees in the lateral plane.
- The dorsal cortical surface of radius thickens to form the Lister tubercle as well as osseous prominences that support the extensors of the wrist in second dorsal compartment.
- A central ridge divides the articular surface of the radius into a scaphoid facet and a lunate facet.
- The triangular fibrocartilage extends from the rim of the sigmoid notch of the radius to the ulnar styloid process.
- Only the brachioradialis tendon inserts onto the distal aspect of the radius; the other tendons of the wrist pass across the distal aspect of the radius to insert onto the carpal bones or the bases of the metacarpals.
- In addition to the extrinsic ligaments of the wrist, the scapholunate interosseous and lunotriquetral interosseous ligaments maintain the scaphoid, lunate and triquetrum in a smooth articular unit that comes into contact with the distal aspect of the radius and the triangular fibrocartilage complex.
- Because of the different areas of bone thickness and density, the fracture patterns tend to propagate between the scaphoid and lunate facets of the distal aspect of the radius.
- The degree, direction and extent of the applied load may cause coronal or sagittal splits within the lunate or scaphoid facet.
Associated Conditions
Conditions associated with poor bone quality leading to distal radius fracture include:
- Osteoporosis
- Osteopenia
- chronic stroke
- Diabetes
- Rheumatoid arthritis
- Chronic kidney disease
- Hyperparathyroidism
- Hypophosphatemic rickets
- Immobility
- Menopause
- Multiple myeloma
- Mixed connective tissue disease
- Paget's disease of bone
- Primary hypoparathyroidism
- Short stature
- Chronic corticosteroid use
Gross Pathology
On gross pathology, decreased bone density and small pores in diaphysis of bones are characteristic findings of osteoporosis, leading to distal radius fracture.
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Microscopic Pathology
- Bone with osteoporosis shows increased number of osteoclasts and decreased number of osteoblasts under the microscope.[9]
- Autophagy is the mechanism through which osteocytes evade oxidative stress.
- The capability of autophagy in cells decreases as they age, a major factor of aging.
- As osteocytes grow, viability of cells decrease thereby decreasing the bone mass density.
References
- ↑ Brown, Charles (2015). Rockwood and Green's fractures in adults. Philadelphia: Lippincott Williams & Wilkins/Wolters Kluwer Health. ISBN 9781451175318. Check
|isbn=value: invalid character (help). - ↑ Elstrom, John (2006). Handbook of fractures. New York: McGraw-Hill, Medical Pub. Division. ISBN 9780071443777.
- ↑ Azar, Frederick (2017). Campbell's operative orthopaedics. Philadelphia, PA: Elsevier. ISBN 9780323433808.
- ↑ Fernandez, Diego (2002). Fractures of the Distal Radius : a Practical Approach to Management. New York, NY: Springer New York. ISBN 9781461300335.
- ↑ Havemann D, Busse FW (1990). "[Accident mechanisms and classification in distal radius fracture]". Langenbecks Arch Chir Suppl II Verh Dtsch Ges Chir: 639–42. PMID 1983626.
- ↑ Meena S, Sharma P, Sambharia AK, Dawar A (2014). "Fractures of distal radius: an overview". J Family Med Prim Care. 3 (4): 325–32. doi:10.4103/2249-4863.148101. PMC 4311337. PMID 25657938.
- ↑ Gong XY, Rong GW, An GS, Wang Y, Zhang GZ (2003). "[Selection of dorsal or volar internal fixation for unstable distal radius fractures]". Zhonghua Wai Ke Za Zhi. 41 (6): 436–40. PMID 12895353.
- ↑ Couzens GB, Peters SE, Cutbush K, Hope B, Taylor F, James CD; et al. (2014). "Stainless steel versus titanium volar multi-axial locking plates for fixation of distal radius fractures: a randomised clinical trial". BMC Musculoskelet Disord. 15: 74. doi:10.1186/1471-2474-15-74. PMC 3984716. PMID 24612524.
- ↑ Onal M, Piemontese M, Xiong J, Wang Y, Han L, Ye S; et al. (2013). "Suppression of autophagy in osteocytes mimics skeletal aging". J Biol Chem. 288 (24): 17432–40. doi:10.1074/jbc.M112.444190. PMC 3682543. PMID 23645674.