Dynamic Hip Screw - DHS
The Dynamic Hip Screw (DHS) or Sliding Hip Screw can be used as a fixation for neck of femur fractures. This would usually be considered for fractures that occur outside the hip capsule (extracapsular), often stable intertrochaneric fractures. This is because there is a reduced chance of interruption to the blood supply to the head of the femur, and so it may be possible to preserve the joint. However, it may also be appropriate for younger patients with fractures within the hip capsule (intracapsular) if there is a good chance that the blood supply is preserved, reducing the risk of avasular necrosis.
History of the DHSPrior to the use of DHS sliding screws, angled blade plates were used. These fixed plates matched the angle of the femural head. These plates had a number of complications, including failure to purchase, requiring frequent osteotomies. They also did not allow any compression across the fracture site, leading to stress failures and frequent non-union. Therefore, the DHS, with sliding barrel, was created to allow controlled compression across the fracture site. This is important for bone healing.
NICE Guidelines recommends: Use extramedullary implants such as a sliding hip screw in preference to an intramedullary nail in patients with trochanteric fractures above and including the lesser trochanter (AO classification types A1 and A2).
Considerations post surgery:
- Post op instructions and weight bearing status
- Infections / wound healing
- Neurovascular complications
- Self-efficacy and motivation
- Fear of falling
Any transfer or mobility aids will be determined by the weight bearing status (usually highlighted in the op note). If the surgeon feels the hip needs protecting post surgery, they may advise partial or non-weight bearing for the patient.Physiotherapy interventions:
- Transfers (bed, chair, toiletting).
- Mobility (+/- appropriate aid).
- Goal setting
- Advising patient and team on pain management and expectations post-surgery
- Advice on swelling management
- Balance retraining and confidence building
- Gait retraining
- Considering home environment.
- Interactions with family and carer
It is important that the patient is transferred out of bed, within these limitations, as early as possible to avoid complications of bed rest (e.g. chest infections, DVT, muscle atrophy). NICE guidelines advise, unless contraindicated, for patient's to mobilise the day after surgery. Physiotherapy exercises post hip surgery:
|After surgery||After 6 weeks|
|Supine||Hip ABD and heel slides (slide sheet can reduce friction)||Inner Range Quads||Bridges (unless NWB)|
|Sitting||Knee extension||Knee flexion||Sit to stand (one balance optimised)|
|Standing||Once able to maintain independent standing balance. Hip Abduction||Hamstring Curl and||Heel Raises and|
DHS Vs Hemiarthroplasty:
Compared to hemiarthroplasty, the DHS has been found to have a superior hip functional outcome. However, the DHS has a higher chance of blood loss requiring blood transfusion and complications requiring revisions. Both were comparable for duration of surgery, length of stay in hospital and early mobilisation. Therefore, may have benefits for return to function for a selected patient group.
Internal fixation of NOF:
The FAITH study (2014) suggests that most studies into internal fixation of fractured NOF compare against hemiarthroplasty. This means there is a lack of evidence for different methods of internal fixation. RCTs with direct comparison are too small and lack sufficient power. Therefore, the FAITH study looked at the effects on patients after cancellous screws and sliding screws.
The FAITH study (2017) suggests that both are comparable for revision / reoperation rates at 24 months, but the sliding hip screw group had a greater instance of avasular necrosis. However, this was not a significant difference and the DHS was found to be more beneficial for displaced fractures and reduced rates of reoperation. It was also thought to be beneficial for those with poor bone density, such as smokers. The authors noted that this finding of benefits for displaced fractures was inconsistent with other study findings.
Precautions post surgery
- Post surgical complications
- Intra-capsular surgery may require a period of partial or protected weight bearing to ensure no displacement of the humeral head
- Avasular necrosis of the femural head
- Operation site infections
- Foot drop post-op
- Risk of fracture to bone below metal plate
- Non-union or malunion
Rarely, the hip screw might protrude into the hip joint articular surface. This can present as increased pain on mobilisation and may result in surgical intervention, such as revision to a hemi to total hip replacement.
- Dodds et al. The Sliding Hip Screw Current Opinion in Orthopaedics (2004) Volume 15, Issue 1 pp12-17
- Singh A.P. Dynamic Hip Screw Or Sliding Hip Screw. [online] Available at: <http://www.boneandspine.com/dynamic-hip-screw/> [Accessed 19 September 2020].
- NICE Hip Fracture: Management <available from: https://www.nice.org.uk/guidance/cg124/chapter/Recommendations#analgesia> [accessed 19/9/20]
- Mue D.D Outcome of Treatment of Fracture Neck of Femur using Hemiarthroplasty Vs Dynamic Hip Screw Journal of West African College of Surgeons (2013)3(2)
- FAITH investigators Fixation using alternative implants for the treatment of hip fractures (FAITH): design and rationale for a multi-centre randomized trial comparing sliding hip screws and cancellous screws on revision surgery rates and quality of life in the treatment of femoral neck fractures BMC Musculoskeletal Discorders (2014) 15(219) doi: 10.1186/1471-2474-15-219
- Bandhari M. Fracture Fixation in the Operation Management of Hip Fractures (FAITH): An international, Multicentre, Randomised Control Trial. Lancet (2017) 15:389 1519-1527
- Dabis J. et al Implant failure in a proximal femoral fracture treated with dynamic hip screw fixation Journal of Surgical Case Reports (2015) Volume 2015 issue 7.