Screws are commonly used during orthopedic surgery to hold bones together while they heal after a fracture. The screws provide stability and alignment while new bone forms around them over time. The healing process varies depending on the location and severity of the fracture. Generally, initial bone healing occurs within 6-12 weeks but complete remodeling can take 3-6 months or longer.
Factors affecting healing time
Several factors influence the amount of time it takes for bone to heal around surgically inserted screws:
Location of fracture
The location of the fractured bone significantly impacts healing time. For example:
| Fracture location | Healing time |
|---|---|
| Ribs | 6-8 weeks |
| Arm (humerus) | 12-16 weeks |
| Leg (femur) | 16-32 weeks |
In general, bones with more blood flow, like ribs, heal faster than bones with less blood flow, like the femur.
Severity of fracture
More severe fractures that are unstable or displaced take longer to heal than hairline cracks or simple breaks. Complete fractures that damage surrounding soft tissues and blood vessels can double healing time.
Patient health
Age, medical conditions, medications, smoking, alcohol abuse, and nutrition impact healing potential. Younger, healthier patients generally heal faster than older patients or those with chronic diseases or poor diets. Osteoporosis also delays healing.
Surgical technique
Proper alignment, stable fixation, bone grafting, and minimal soft tissue disruption during surgery all help optimize healing. Poor surgical technique resulting in unstable fixation or infection can prolong healing.
Early healing stages
Bone healing after fracture fixation with screws occurs in several overlapping stages:
Hematoma formation
Within hours of the fracture, bleeding results in a hematoma, which delivers essential growth factors, stem cells, and nutrients to initiate healing. This lasts around 5 days.
Inflammation
Inflammation peaks around 3-7 days as the body removes dead tissue. This prepares the area for new bone formation.
Soft callus formation
Mesenchymal stem cells differentiate into chondrocytes to form a soft, cartilage-like callus between bone fragments around 7-14 days. This stabilizes the fracture.
Hard callus formation
The soft callus begins to calcify into hard callus within 2-3 weeks. This solid bony tissue forms around fracture edges and screws.
Bone remodeling
Over 6-12 weeks, osteoclasts resorb excess callus while osteoblasts rebuild new lamellar bone. The medullary canal reforms over 3-6 months as bone remodeling continues.
Factors affecting early healing
The early stages of bone healing depend on:
Adequate blood supply
The hematoma delivers critical cells and proteins to initiate repair. Disrupted blood vessels from severe injury delay early healing.
Reduction and fixation
Accurate bone alignment and stable internal fixation with screws provides an optimal environment for bone cells to proliferate and form new bone matrix.
Gap size
Smaller fracture gaps fill with bone faster than large defects. Larger gaps may require bone grafting to stimulate healing.
Infection
Invasive bacteria impair hematoma formation, cell function, and blood flow. This can prevent progression to callus formation.
Patient health
Good nutrition, especially protein, vitamin D, and minerals like calcium and magnesium encourage early healing stages. Medical conditions, age, or medications may slow the process.
Later healing stages
After initial callus formation, bone healing progresses through:
Primary bone formation
Woven bone forms rapidly but disorganized around the fracture site between 6-12 weeks. This bridges the gap but is weaker than mature bone.
Lamellar bone formation
Over 3-6 months, woven bone transitions to stronger lamellar bone as collagen fibers realign. The medullary canal also regenerates.
Bone remodeling
Osteoclasts resorb remaining disorganized bone while osteoblasts form new lamellar bone. This remodeling can take years until the bone returns to its original shape and strength.
Factors affecting later healing
Later bone healing stages depend on:
Callus formation
Robust, mineralized callus provides a template for bone cells to generate new woven bone. Inadequate callus delays primary bone formation.
Mechanical stresses
Controlled loading encourages later remodeling into stronger lamellar bone while stress shielding from plates delays maturation. Early weightbearing usually quickens healing.
Blood supply
Rich blood circulation brings nutrients and oxygen to stimulate osteoblast activity and bone growth. Poor blood flow stunts regeneration.
Age and health
Younger patients form bone faster than elderly patients due to enhanced cell function and activity. Medical conditions or medications can inhibit bone remodeling.
Physical therapy
Exercise directs connective tissue formation along tension lines. PT improves bone alignment, strength, and function during healing.
Healing timeline by fracture location
Here is a general timeline for bone healing around screws by fracture site:
Clavicle
| Stage | Timeframe |
|---|---|
| Hematoma formation | First week |
| Soft callus | 2-4 weeks |
| Hard callus | 4-8 weeks |
| Remodeling | 3-6 months |
Humerus
| Stage | Timeframe |
|---|---|
| Hematoma formation | First week |
| Soft callus | 3-6 weeks |
| Hard callus | 6-12 weeks |
| Remodeling | 6-9 months |
Tibia
| Stage | Timeframe |
|---|---|
| Hematoma formation | First week |
| Soft callus | 4-8 weeks |
| Hard callus | 8-16 weeks |
| Remodeling | 9-18 months |
Femur
| Stage | Timeframe |
|---|---|
| Hematoma formation | First week |
| Soft callus | 6-12 weeks |
| Hard callus | 12-24 weeks |
| Remodeling | 18-36 months |
Signs of impaired bone healing
Delayed healing or nonunion around fracture fixation screws may be indicated by:
Persistent pain
Unresolved pain beyond the normal healing period may signal complications.
Instability
Excess movement at the fracture site indicates lack of bridging callus formation.
Failure to bear weight
Inability to bear full weight weeks after surgery implies inadequate structural integrity.
Visible gap or deformity
A visible fracture line or angulation suggests poor alignment or progression of healing.
Failure of screws
Loosening, breaking, or backing out of screws indicates instability and insufficient bone growth around screws.
Lack of progression on imaging
X-rays, CT scans, or MRIs that show no evidence of healing over time often mean delayed union or nonunion.
Treatment for impaired healing
If bone fails to heal around screws, treatment options include:
Bone stimulation
Low intensity ultrasound or electromagnetic fields may stimulate osteoblasts and new bone growth in difficult fractures.
Surgical revision
Additional surgery can improve alignment, compress fragments, add bone graft, exchange fixators, or modify immobilization to enhance healing.
BMPs
Applying bone morphogenetic proteins (BMPs) during revision surgery may promote ossification in challenging nonunions.
Medications
Anti-resorptive bisphosphonates, parathyroid hormone, or growth factors like FGF may help when systemic factors impair bone formation.
Alternative healing methods
For recalcitrant nonunions, alternatives like PRP, stem cells, or shockwave therapy could stimulate bone regeneration when standard techniques fail.
Conclusion
Complete bone healing and remodeling around fracture fixation screws takes around 3-6 months for less severe injuries but can extend up to 1-2 years for high impact trauma requiring extensive reconstruction. The location, health of bone and soft tissue, surgical technique, postoperative care, and patient factors all influence the speed and progression of healing through the overlapping phases of hematoma formation, inflammation, callus generation, ossification, and remodeling. Monitoring for signs of delayed union or nonunion allows timely intervention with bone stimulation, medications, revision surgery, or other modalities to encourage bone regeneration when standard fracture healing is impaired around screws. With proper treatment, most fractures will eventually heal.
