Micromotion Clinical Evidence

Micromotion Clinical Evidence2024-05-10T08:58:57+01:00

Unmet Clinical Need

After a long bone fracture, 1 in 4 patients experience problems with their bone healing. Delayed union occurs when the bone is slow to heal. Some of these patients do not heal at all, a condition known as nonunion.

Nonunion and Delayed healing in tibial fractures infographic

Evidence based on tibial fractures treated in North American Level I Trauma Centers, U.S. Managed Care Claims Data, and UK + Europe. Tibial nonunions are reported to occur at a rate of between 7-19% (according to various published articles).

Nonunion patients may require multiple surgeries over a protracted period of care. Compared to patients healing normally, nonunion patients have more pain and longer duration of opioid use, higher rates of depression requiring treatment, and longer periods of disability resulting in more lost earned income. Less than 60% of tibial fracture nonunion patients return to work within one year.

The Apex Nailing System was designed to promote faster fracture healing and reduce the clinical problems of delayed healing and nonunion.

Study Design

A recently completed clinical study examined how the Apex Tibial Nailing System with micromotion fixation compares to the current standard of care (static locking) for treatment of tibial shaft fractures. This study reported:

  • 1
    Healing Speed (time to clinical union)
  • 2
    Incidence of complications including delayed healing and nonunion
  • 3
    Early mechanical integrity of new bone

Patients in the micromotion group had Apex Tibial Nails. These implants generate beneficial passive motion during the early healing period while a patient goes about their normal activities of daily living. The Apex Tibial Nail has the following design features:

  • Controlled axial micromotion is enabled by a gliding insert in the proximal end of the nail stem. This design provides 1 mm of axial motion to mechanically stimulate bone growth.
  • Best-in-class torsional stability is created by the insert design, which prevents rotation of the bone fragments. and is the first and only micromotion-enabled IM nailing system designed to stimulate bone healing
  • Insert micromotion locking image.

The Apex micromotion was compared to a control group treated with conventional intramedullary nails in standard-of-care static locking mode. Static locking means that the implant does not generate passive micromotion.

Patients in this study were enrolled at the time of their surgery and followed for one year. All cases were completed in a single Level I trauma center by multiple surgeons. Cases included a wide range of fracture types, including open and closed injuries and a mixture of high- and low-energy injuries.

Clinical Results

In summary the recently completed clinical study examined how the Apex Tibial Nailing System with micromotion fixation compares to the current standard of care (static locking) for treatment of tibial shaft fractures. This study reported:

  • Healing speed (time to clinical union)

  • Incidence of complications including delayed healing and nonunion

  • Early mechanical integrity of new bone

The study showed superior results with Apex micromotion across all key clinical outcomes measures. There were zero nonunions in any micromotion patient, versus 11% nonunion in the control group. Micromotion patients also healed faster than static locking patients, resulting in fewer delayed unions.

CT scan analysis showed that micromotion substantially increased bone formation in patients who had increased risk for problems in bone healing due to health comorbidities like smoking and diabetes.

Overall, the pilot study suggests that Apex micromotion nailing has potential to decrease the clinical incidence of delayed healing and nonunion and increase the speed of healing for all patients.

Read the study article published in Bone & Joint Open Journal.

Read Clinical Whitepaper

Case Example

Case D (Figure 5): Male, age 55, crushed between two vehicles and sustained an open (Gustilo-Anderson IIIB) tibial fracture, OTA/AO 42-C3. Soft tissue injury was extensive with degloving and muscle loss, but no arterial damage. Primary fixation by reamed nailing was undertaken with debridement and flap coverage by a plastic surgery team. RUST scores at 6 and 12 weeks were 8 and 12. Proliferative callus
was observed on the 12-week CT scan and the limb had achieved a normalized virtual torsional rigidity, VTR = 0.87 (fractured/intact), which indicates that surprisingly advanced structural healing had already taken place, given the severity of the soft tissue injury.

Clinical union was achieved by 12 weeks and the patient continued with no sign of infection, no additional procedures, and good functional recovery with minimal pain. Given the high energy injury in combination with the degree of communication and soft tissue loss, to achieve robust callus bridging at 12 weeks is an exemplary healing result.

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