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What is better between cancellous locking or cortical locking screws in cancescolous bone

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"locking screw" AND cancellous bone

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Short answer

Cancellous-thread locking screws are generally the better choice when the screw shaft is purchasing true cancellous (trabecular) bone - e.g., metaphyseal/epiphyseal segments, femoral neck/head, proximal humerus, proximal tibia, calcaneus, or osteoporotic bone. Cortical-thread locking screws are reserved for diaphyseal cortical bone or for the far-cortex bite of a bicortical screw.

Why

Locking screws differ from conventional screws in how they fix to the plate (a fixed-angle, threaded screw-head/plate-hole interface rather than friction-compression), but they still come in two thread geometries for the shaft that grips bone:
  • Cortical thread: fine pitch, shallow, fully-threaded - designed to cut into dense, hard cortical bone.
  • Cancellous thread: coarser pitch, deeper/wider threads, often only partially threaded - designed to engage the loose trabecular struts of cancellous bone and maximize thread-to-bone contact area.
Because cancellous bone has much lower density than cortical bone, a fine cortical thread strips or "auger's out" trabeculae with minimal purchase. The wider, deeper cancellous thread engages more trabecular surface per turn, which improves pull-out and toggle resistance in low-density bone - the same principle that governs conventional (non-locking) screw selection:
"Cortical screws can be used in young patients, while cancellous screws can be used in osteoporotic bone. Some plates have locking screw capability, which may be beneficial in osteoporotic bone." - Rockwood and Green's Fractures in Adults, 10th ed.
"Nonlocking screws compress plate to bone and can be used to lag in fragments; locking screws provide angular stability in short metaphyseal segments or in osteoporotic bone." - Miller's Review of Orthopaedics, 9th ed.
"...poor purchase within the cancellous bone of the head, especially in osteoporotic patients... To overcome this problem, some nails/screws provide... locking [mechanisms]." - Rockwood and Green's Fractures in Adults, 10th ed.
A 2025 biomechanical pilot study specifically modified a cancellous-thread locking screw design and showed further gains in axial pull-out strength when engaging cancellous bone (Hsu et al., Bioengineering, 2025, PMID 40428063), reinforcing that thread geometry - not just the locking mechanism - matters once the screw is seated in cancellous bone.

Practical nuance

  • The locking mechanism itself (fixed-angle screw head threading into the plate hole) is what gives the construct angular stability and resistance to toggle in osteoporotic/cancellous bone, regardless of thread type on the shaft - this is the main reason locking screws outperform conventional screws in poor bone quality.
  • Bicortical locking screws (crossing into the far, denser cortex) improve torsional resistance over unicortical screws, per Rockwood and Green's, so a screw that starts in cancellous bone but bicortically engages the opposite cortex may use a cortical thread for that far-cortex purchase.
  • Most locking plate systems (LCP, LISS, etc.) offer both thread options on the same plate so the surgeon can mix cortical-thread locking screws in the diaphysis and cancellous-thread locking screws in the metaphyseal/epiphyseal segment of the same construct.
Bottom line: if the screw is truly anchored within cancellous/trabecular bone (not bicortical into a far cortex), a cancellous-thread locking screw gives better mechanical purchase than a cortical-thread locking screw in that same bone.
I did not find a recent systematic review or meta-analysis directly comparing cancellous vs cortical locking screw thread designs in cancellous bone - the evidence above is drawn from major orthopedic trauma textbooks plus a single 2025 biomechanical pilot study, so if you need level-1 evidence for a specific fracture pattern, let me know and I can dig further into PubMed for that specific anatomic region (e.g., proximal humerus locking plates, femoral neck fixation).
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