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Bone Injuries of the Lower Limb
Stress reactions and stress fractures are caused by repetitive overload injuries to bones, and they are common in individuals who participate in endurance activities, such as distance running (eSlide 36.
14). Intrinsic risk factors include poor dietary habits, altered menstrual status, and biomechanical abnormalities that do not allow for proper distribution of forces along the kinetic chain.
Extrinsic factors can include types of training surfaces, footwear, and insoles or training errors. The patient usually provides a history of a recent acceleration in the intensity or duration of training and complains of insidious onset of focal pain that is exacerbated with weight-bearing activities.
In some stress fractures, such as femoral neck or navicular fractures, symptoms can be vague, thus increasing the time to diagnosis. The differential diagnosis usually includes tendinopathy, enthesopathy, and CECS. CT provides optimal definition of the bony architecture.
A 6-week period of relative rest with nonimpact rehabilitation and alternative training methods, such as pool running, can be instituted. Most stress fractures heal without complication with activity modification and allow gradual return to sports in 4–8 weeks.
Initial treatment includes pain management using acetaminophen (not NSAIDs, which might prevent optimal repair of the stress fracture), ice application, activity modification, strengthening exercises, fitness maintenance, and risk factor modification.
Cross-training activities, such as cycling, swimming, water running, rowing, and use of StairMaster, are recommended to maintain cardiopulmonary fitness. A progressive increase in load is necessary to allow the bone to adapt by increasing its strength.
Specific treatment is required for some stress fractures that may develop complications: femoral neck, anterior cortex of the middle third of the tibia, navicular, and proximal fifth metatarsal fractures.
In femoral neck stress fractures, symptoms are often vague, and an MRI should be obtained to establish the diagnosis and reduce the risk of complications, such as fracture displacement or avascular necrosis (eSlide 36.15).
Fractures on the compression side are more common. If the fracture line extends greater than 50% of the width of the femoral neck, percutaneous fixation should be considered because the likelihood of displacement is increased. In other cases, strict non-weight bearing is necessary for approximately 4–6 weeks until the patient is pain free. This should be followed by functional rehabilitation with progressive weight bearing over the next 4–8 weeks (according to symptoms). Navicular fractures have a higher likelihood of delayed union, nonunion, or avascular necrosis. Therefore, early diagnosis by MRI, bone scan, or CT and appropriate treatment are important. If these fractures propagate across the body of the bone, early surgical intervention should be considered.
Having a sound understanding of anatomy and kinetic chain biomechanics, in conjunction with fundamental history and physical examination skills, permits a practitioner to establish appropriate diagnoses for patients presenting with soft tissue, bone, and joint disorders of the lower limbs. Imaging studies can help confirm clinical diagnoses. The majority of lower limb injuries can be successfully treated with nonoperative measures that include medications, activity modification, and intelligent exercise strategies. The practitioner should be able to recognize injuries that require surgical consultation.
KEYSTONE, COLO — For patients with tarsal navicular stress fractures, healing rates and return-to-activity times are similar, regardless of whether they are managed with non-weight-bearing cast immobilization or surgery, according to a meta-analysis.
This finding undercuts the basis for the growing trend of surgical management of these challenging foot injuries. The assumption—now shown to be baseless—has been that operating on tarsal navicular stress fractures facilitates early return to activity, said Dr. Barry P. Boden, an orthopedic surgeon at the Uniformed Services University of the Health Sciences in Bethesda, Md.
He presented a systematic review and meta-analysis of 31 articles, mostly case series, which included 253 partial or complete tarsal navicular stress fractures, at the annual meeting of the American Orthopaedic Society for Sports Medicine.
His conclusion: “Non-weight bearing is indicated as initial therapy and following failed weight-bearing management of both partial and complete fractures.”
“With increased awareness and today’s improved imaging techniques, it’s rare for a tarsal navicular stress fracture to present as a nonunion or displaced fracture,” he added. “Thus, surgery in the form of open reduction and internal fixation plus or minus bone grafting is rarely if ever indicated.”
Six weeks of immobilization in a non-weight-bearing cast showed a strong trend for a higher rate of fracture healing and freedom from pain than did surgery, but the difference didn’t reach statistical significance. (See chart.) Time to return to activity was approximately 5 months with either therapy.
“Return to play takes a long time. You’re talking 6-8 weeks in a cast, then gradually advancing to weight bearing, and then to full activity,” Dr. Boden said.
Non-weight-bearing cast immobilization and surgery both had significantly higher successful outcome rates than did weight-bearing casting and/or rest.
“Again, non-weight bearing is an absolute in the management of these injuries. Clinical and imaging findings should determine return to activity,” Dr. Boden continued.
Dr. Thomas O. Clanton, the session moderator, said “this is a great meta-analysis” but added that he doesn’t consider it to be the final word because the available literature is all level 4 evidence. “Even the paper by Saxena purported to be level 1 is not a level 1 study,” he said (J. Foot Ankle Surg. 2000;39:96-103).
“Almost all the papers rely on x-ray diagnosis and follow-up of patients, and nowadays we use CT scans. So I don’t think you can say all those fractures in the literature that are said to be healed really did heal. We’ve found a number of patients we’ve treated nonoperatively who, when you look at them again at 6 or 8 weeks, may be asymptomatic, but they still have obvious fracture lines on CT scans,” said Dr. Clanton of the University of Texas, Houston.
It’s also very difficult to convince someone who weighs more than 250 pounds to be non-weight bearing for 6 weeks, with the possibility that they might be non-weight bearing even longer if that were to fail, he added.
Dr. Boden’s coinvestigator in the meta-analysis, Dr. Joseph S. Torg of Temple University, Philadelphia, is credited with developing the non-weight-bearing cast immobilization regimen for navicular tarsal stress fractures a quarter century ago. That method entails 6 weeks of cast immobilization. Dr. Boden said recent data suggest successful outcomes are achievable with less than 6 weeks of immobilization, although this issue requires further study.
‘Open reduction and internal fixation plus or minus bone grafting is rarely if ever indicated.’
Source DR. BODEN
Source ELSEVIER GLOBAL MEDICAL NEWS
Having a sound understanding of anatomy and kinetic chain biomechanics, in conjunction with fundamental history and physical examination skills, permits a practitioner to establish appropriate diagnoses for patients presenting with soft tissue, bone, and joint disorders of the lower limbs.
Imaging studies can help confirm clinical diagnoses. The majority of lower limb injuries can be successfully treated with nonoperative measures that include medications, activity modification, and intelligent exercise strategies. The practitioner should be able to recognize injuries that require surgical consultation.
As with most periarticular regions, there are several potential complications and risks associated with fractures of the navicular. These complications include osteonecrosis, malunion, nonunion, persistent stiffness, and pain.
Patients suffering a nonunion may have deformity which can be mitigated through the use of an orthosis or surgical revision, depending on the severity of the deformity. Osteonecrosis, however, can result in profound deformity and is typically treated with the primary goal of restoring length and alignment, which is often through the fusion of the talonavicular or naviculocuneiform joints.
Deterrence and Patient Education
Navicular stress fractures are caused by overuse in the vast majority of instances, explaining the high incidence in competitive athletes. With this in mind, it is necessary to inform the patient of the value of proper training and technique in their athletic activities, as well as using appropriate equipment to reduce the amount of stress placed upon the foot.
In the event of a suspected navicular fracture, some conditions that may have similar symptoms and presentations include tendinopathy of the posterior tibialis owing to its insertion on the navicular tuberosity, tear of the spring ligament, or separation of an accessory navicular- a relatively common anatomic variant.
An MRI can differentiate between a tarsal navicular fracture and one of these conditions. However, it is usually not needed in the initial management as radiographs, and CT-scans readily diagnose most tarsal navicular fractures.