Extensor Mechanism Injuries

The extensor mechanism comprises of the quadriceps muscles and tendon, medial and lateral retinacula, patella, patellar tendon, and tibial tubercle. Tendons of the extensor mechanism are extremely resistant to tensile loads and do not rupture under normal physiologic conditions, even with significant degrees of stress. Injury generally happens due to sudden vigorous contraction of the muscle with the knee in a flexed position, laceration, or a direct impact. Disruption may occur at any level from the quadriceps muscle to the insertion on the tibial tubercle. 

Rupture of the quadriceps tendon usually occurs at or just proximal to the patellar inser- tion. Occasionally the rupture may extend into the vastus intermedius tendon or transversely into the retinaculum. Most patellar tendon ruptures occur at the site of origin on the inferior pole of the patella.

Quadriceps tendon rupture > 40 years 

Patellar tendon rupture < 40 years

Risk Factors for Extensor Mechanism Injuries - Chronic systemic conditions, including rheumatoid arthritis, gout, systemic lupus erythematosus, hyperparathyroidism, and iatrogenic immunosuppression in organ transplant recipients, use of steroids/fluoroquinolones. 

Patients with delayed diagnosis of patellar tendon rupture may experience significant retraction of the patella proximally and subsequent development of quadriceps contractures or adhesions. 

Clinical Features. Clinical evaluation can elicit the correct diagnosis in most cases of complete disruption. Classical signs are:
1. Acute onset of pain, swelling, and ecchymoses over the anterior aspect of the knee and a palpable defect in the patella, quadriceps tendon, or patella tendon
2. Loss or limitation of ability for active leg extension - extension lag usually is seen when the last 10 degrees of extension is performed haltingly or with difficulty)
3. High- riding patella (patella alta) with patellar tendon rupture and superior retraction
4. Low-riding patella (patella baja) with quadriceps tendon rupture and inferior retraction. 

Partial disruptions may not show these clinical signs and may require MRI for confirmation.

Diagnostic Imaging
AP and Lateral X Rays Knee

• Obliteration of the quadriceps or patella tendon, a poorly defined suprapatellar or infrapatellar soft tissue mass (represents proximal or distal retraction of the torn tendon), soft tissue calcific densities (represent avulsed bone fragments of the patella or tibial tubercle), or a displaced patella.
• Patella alta may be sought on the lateral radiograph using a ratio of patellar length to patellar tendon length (the Insall-Salvati ratio). The Insall-Salvati ratio (TL/PL) is considered normal between 0.8 and 1.2. Patella baja: <0.8, patella alta: >1.2. 

Ultrasound has low sensitivity and specificity in diagnosing acute quadriceps and patellar tendon ruptures. MRI shows the entire extensor mechanism and is the best imaging modality for diagnosing pathology in this system, even in the acute phase. MRI usually is reserved for patients with possible incomplete disruption or for those with a complication of intra-articular derangements. 

Management

Early Repair - within 2 to 6 weeks of the initial injury. If the tear is only partial, immobilization with the knee in full extension for 4 to 6 weeks is the treatment of choice. Surgical intervention is required for reattachment of complete tendon ruptures, and repair should be performed as soon as possible. After primary repair, the knee is immobilized in full extension with a long leg cast until healing is complete. Gradually progressive active and passive range-of-motion exercises are indicated for optimal results.

Posted by:

              

     Lakshay Chanana

     

     ST4 Trainee

     Royal Infirmary of Edinburgh

     Department of Emergency Medicine

     Edinburgh

     Scotland

     @EMDidactic

Proximal Femur fractures

Introduction

Proximal femur fractures are a common injury, particularly in the elderly. If seen in the younger population then it signifies significant degree of forces involved. Fractures can be described as intracapsular (NOF) or extracapsualar (intertrochanteric, transtrochanteric and subtrochanteric). Intracapsular fractures are at high risk of non-union and avascular necrosis due to compromisedd blood supply and often arthroplasty (either hemiarthroplasty or total hip replacement) may be indicated for these fractures. It is important to always consider the possibility of a pathological fracture in any patient who has a known diagnosis of malignancy. 

Intracapsular - Commonly referred to as NOF. Typically seen in elderly patients who present with trivial trauma, such as a fall from standing height. They patints often have osteoporosis or a lytic lesion. Neck of femur fractures are classified into 4 grades according to the Garden system based on an increasing degree of displacement. 

The management of intracapsular fracture depends on the degree of displacement and to a degree the fitness of the patient. Undisplaced fractures are fixed (cannulated hip screws) and displaced fractures are replaced, usually with a hemiarthroplasty. 

Exceptions - Displaced fractures in fit young patients should be fixed within 6 hours rather than replaced because there is a high risk of avascular necrosis, to insert a joint replacement in younger patients is the last resort as it will almost certainly need multiple revision surgeries as the total hip replacement wears out. healthy patients between the ages of 40 and 60 would do poorly with a hemiarthroplasty as they still have a high functional demand. These patients should be treated with a total hip replacement which has much better functional outcomes. 

Intertrochanteric - Extracapsular injuries and thus pose little concerns to the blood supply of the femoral head. Treatment is fixation rather than replacement. Generally fixed with a compression hip screw. 

Subtrochanteric - Extracapsular fractures typically seen in two circumstances ie. high energy trauma and due to lytic lesions. Occasionally also seen as fragility fractures in the elderly. Fixation is the treatment of choice and intramedullary nail with a hip screw is typically used.


ED Management

• Pain Relief - Low dose opioids/FICB
• Bloods and CXR - Preop
• IV Fluids
• Look for concomitant injuries  and other acute medical problems 
• Ortho Referral

Posted by:

              

     Lakshay Chanana

     

     ST4 Trainee

     Royal Infirmary of Edinburgh

     Department of Emergency Medicine

     Edinburgh

     Scotland

     @EMDidactic

Septic Arthritis

Septic arthritis is a destructive disease process classically presenting as a red, hot and swollen joint. The disease has a bimodal incidence, which peaks in young children and adults over age 55 years. Unfortunately, septic arthritis is not always easy to diagnose and  presentations may be subtle without classical signs, symptoms, or laboratory markers. It remains one of those cannot miss diagnosis which are always fraught with fear. Therefore, the dictum is "Red Hot Swollen joints should be tapped" to r/o Septic Joint.   Fluid is then sent for Gram Stain, C/S, White Cell count and Differential count, and Crystal analysis. 

Routes of Spread: Common routes of spread is hematogenous followed by direct inoculation (trauma or localised spread from a surrounding soft tissue infection)

Common Joints - Knee>Hip>Shoulder>Elbow


Risk Factors for Septic Arthritis (More abnormal joint, more likely Septic Arthritis)

• Bacteremia/systemic infection
• IVDU (may have sternoclavicular and sternomanubrial joint involvement)
• Overlying skin infection
• Diabetes Mellitus
• Arthritic Joints, Prosthetic joints
• Elderly, Immunocompromised states
• Recent joint surgery or procedure

Common Organisms

• Staph Aures 40%
• Streptocossus 30%
• GNB 20%
• Gonococcal arthritis - Most common cause of septic arthritis in the sexually active patient population. Presents as migratory polyarthritis and may involve several joints (wrist, knee and ankles), or include a rash/tenosynovitis. 4:1 female to male predominance.

Clinical Presentation (No combination of exam findings can definitively diagnose septic arthritis)

• Typical - Swollen, Red, Immobile and Tender joint
• Pain is present in about 80%. Joint tenderness has sensitivity approaching 100%
• Fever is seen only in about 50% 
• Generalized tenderness with painful limitation of active and passive range of motion. Focal tenderness and pain limited to specific movements on an active range of motion testing is more typical of periarticular inflammation (skin, bursa, tendons).

Immunocompromised patients often have polyarticular involvement and present atypically. Sudden onset of pain is more suggestive of intrinsic joint pathology, such as septic arthritis.

Work up (Serum blood tests do not rule out septic arthritis)

• Synovial Fluid Analysis - Synovial fluid with a WBC count > 50,000/mm with a polymorphonuclear cell count > 90%. However, in culture-proven septic arthritis, this WBC count is reached only in 50 – 75% of cases. Therefore, lower WBC counts cannot exclude the presence of septic arthritis. A synovial fluid WBC count >100,000/mm is more specific. MRSA-associated septic arthritis (leading cause in prosthetic joints) may have lower synovial fluid WBC counts only up to 15,000 cells/μL
• Use CRP/ESR/WCC with caution - Normal levels cannot rule out septic arthritis
• Positive Gram stain can be diagnostic; however, a negative result for bacteria cannot rule out septic arthritis (sensitivity only 50-60%). Culture remains the most sensitive test (>90%).
• Presence of crystals shouldnot be used to rule out septic arthritis. Gout and Septic Arthritis can co-exist in the same joint. 

Synovial lactate has the best diagnostic accuracy in septic arthritis, based on several studies. Levels above 10 mmol/L demonstrate +LRs ranging from 20 to infinity

Imaging tests offer little assistance in the diagnosis of septic arthritis. Radiographs may demonstrate effusion or soft tissue swelling. Computed tomography (CT) has greater sensitivity for effusions and edema but is unreliable early in the disease course to evaluate for septic arthritis. Ultrasound (US) can be used to localize joint swelling and target the site for optimal aspiration. 

Management

• Analgesia
• Joint aspiration
• Empiric Antibiotics (should provide gram-positive and gram-negative coverage)
• Orthopedic Referral consultation

Take Home

• More abnormal joint, more likely Septic Arthritis
• Immunocompromised patients often have polyarticular involvement and present atypically. 
• Sudden onset of pain is more suggestive of intrinsic joint pathology, such as septic arthritis.
• Serum blood tests do not rule out septic arthritis
• If suspicion is still high after equivocal or dry tap, admit the patient and initiate empiric IV antibiotics while the synovial culture results

Posted by:

              

     Lakshay Chanana

     

     ST4 Trainee

     Royal Infirmary of Edinburgh

     Department of Emergency Medicine

     Edinburgh

     Scotland

     @EMDidactic

Lisfranc injuries

The Lisfranc joint complex is composed of the bones and ligaments that connect the midfoot to the five metatarsals of the forefoot and Lisfranc ligament connects the base of the second metatarsal to the lateral aspect of the medial cuneiform providing stability to the joint, despite the absence of a ligamentous connection between the first and second metatarsal. 

Lisfranc injuries are a spectrum of injuries which typically occur when an axial load is applied to a plantar-flexed foot. The severity of injury may range from a simple sprain to complete disruption of the tarso-metatarsal joints in the midfoot. These injuries are easy to miss (often diagnosed as a sprain in EDs) because they are rare and often show only subtle or no x-ray findings (1/5 have normal X rays). 

It is important for emergency physicians to be aware of the anatomy of Lisfranc joint complex and have a high index of suspicion for this injury since missed injuries result in long-term misalignment and functional weight-bearing difficulties. 


Clinical Presentation

• Patients are typically unable to weight bear
• Hematoma/ecchymosis on the plantar aspect of the foot
• Significant dorsal midfoot swelling
• Signs of compartment syndrome
• Tenderness to palpation over the midfoot
• Tenderness on twisting the forefoot after stabilising the heel
• Exacerbation of pain with dorsal and plantar flexion of each digit 
• Exacerbation of pain when walking on tiptoes 
• Fleck sign - Small chip fracture from medial margin of the base of M2

Diagnosis

Normal findings on Ankle X Rays:

• On the AP view, the medial edge of the base of the second metatarsal should line up with the medial edge of the middle cuneiform
• The gap between the second metatarsal and medial cuneiform is <2 mm.
• On the oblique view, the medial edge of the third and fourth metatarsal should line up with the medial edges of the middle cuneiform and cuboid, respectively.1
• On the lateral view, the superior border of the first metatarsal should align with the superior border of the medial cuneiform 
• Look for widening between the bases of the 1st and 2nd or 2nd and 3rdmetatarsal bases. Widening >2mm is an indication for urgent surgical intervention

On the AP view (left), the medial edge of the base of the second metatarsal should line up with the medial edge of the middle cuneiform. On the oblique view (right), the medial edge of the third and fourth metatarsal should line up with the medial edges of the middle cuneiform and cuboid, respectively.

Superior border of the first metatarsal aligns with the superior border of the medial cuneiform 

Note widening between medical cuneiform and second metatarsal. Fleck sign - Small chip fracture from medial margin of the base of the second metatarsal

With high suspicion of Lisfranc injury but normal initial X Rays, obtain a30-degree oblique x-rays or do a CT of the foot. 

ED Management

Stable dislocation/fracture injuries are defined as having less than 2 mm of displacement between the first metatarsal and medial cuneiform. These can be managed non-operatively with reduction and casting. The patient should be placed in a non-weight-bearing below-the-knee cast for six weeks and have an outpatient orthopedic follow-up in 2 weeks.  Discharge instruction should include elevation of the leg and warning signs of compartment syndrome of the foot.

For unstable fractures and dislocations ((>2mm widening at the Lisfranc joint), immediate orthopedic consultation is needed for surgical intervention with internal fixation.

Posted by:

              

     Lakshay Chanana

     

     ST4 Trainee

     Royal Infirmary of Edinburgh

     Department of Emergency Medicine

     Edinburgh

     Scotland

     @EMDidactic

Greenstick and Torus fractures

Torus Fractures (Buckle/Cortical Fractures)

Torus fracture is an injury of the cortex on the non-compressive side of the bone with an intact cortex on the tension side. Torus is derived from Latin (tori) meaning a swelling or protuberance. Deformity should not occur in torus fracture because the periosteum and cortex are intact on the side of the bone opposite to fracture. The distal end of the radius is the most common site for a torus fracture. Compressive forces often result in a bulging or buckling of the periosteum rather than a more complete fracture line. these injuries usually involve the metaphysis. A simple torus fracture will not produce a visible deformity to the shape of the extremity; however, there is typically soft tissue swelling and point tenderness over the bony injury. 

Radiographically, the torus fracture may be subtle. Carefully inspect the contour of the metaphyseal flare. Any asymmetry, bulging, or deviation of the cortical margin indicates a torus fracture. Soft tissue swelling is also usually evident. Torus fractures are not associated with angulation, displacement, or rotational abnormalities, so reduction is not necessary. Treat by splinting in a position of function fracture clinic follow-up within 1 week. 

https://radiopaedia.org/cases/torus-fracture-1

Greenstick Fractures
A greenstick fracture is characterized by cortical disruption and periosteal tearing on the convex side of the bone, with an intact periosteum on the concave side of the fracture. Greenstick fractures are more stable and somewhat less painful than complete fractures because the area of intact periosteum limits bony displacement. The need for reduction is determined by the degree of angulation of the fracture, the age of the child, and the anatomic location of the injury.

https://radiopaedia.org/cases/radius-and-ulna-greenstick-fractures

Posted by:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic

Sternoclavicular joint Injuries

Sternoclavicular joint is an  extremely stable joint, due to the strong surrounding ligaments, and thus fracture/dislocations are rare and most injuries simple sprains. Significant forces are required to disrupt the strong ligamentous stabilizers of this joint. The most common causes are MVCs and injuries sustained in contact sports.

 The joint may be anteriorly or posteriorly dislocated.

www.anatomyzone.com

Grading on Injury
Injuries to the SCJ can be graded into three types. A grade I injury is a mild sprain secondary to stretching of the sterno-clavicular and costoclavicular ligaments. A grade II injury is associated with subluxation of the joint (anterior or posterior) secondary to rupture of the sternoclavicular ligament. The costoclavicular ligament remains intact. Complete rupture of the sternoclavicular and costoclavicular ligaments results in a grade III injury (dislocation).

Minor trauma may result in a sprain are treated with with ice, sling, and analgesics and follow up with Orthopaedics. 

Anterior and Posterior Dislocation
Results from a direct blow to the shoulder, causing the shoulder to roll forward. Patients present with severe pain which is exacerbated by arm movement and lying supine. The pain will be exacerbated by lateral shoulder compression, arm movements, deep breathing or coughing.The shoulder may appear shortened and rolled forward. 

http://msk-anatomy.blogspot.co.uk/2012/06/sternoclavicular-joint.html

On examination, anterior dislocations have a prominent medial clavicle end that is visible and palpable anterior to the sternum while in posterior dislocations, the medial clavicle end is less visible and often not palpable, and the patient may have signs and symptoms of impingement of the superior mediastinal contents, such as stridor, dysphagia, and shortness of breath. 

Imaging
CXR is needed to exclude a injuries such as a  pneumothorax, pneumomediastinum, and hemopneumothorax. Routine radiographs have a low sensitivity for the detection of dislocation and thus special views and comparison with the other clavicle may be required. CT remains the imaging procedure of choice and is recommended especially in any posterior dislocation with concern for injury to the mediastinal structures. 

Management

Anterior Dislocation

Patients with uncomplicated anterior dislocations may be discharged without an attempted reduction. Look for concomitant Glenohumeral and Acromioclavicular joint injuries. Clavicular splinting, ice, analgesics, sling, and orthopedic referral are required.

Closed reduction may be performed within 10 days of the injury by placing the patient supine with a towel rollin between the shoulder blades. The arm is then abducted to 90 degrees and longitudinal traction is applied with slight extension by moving the arm toward the ground, and pressure is placed over the medial end of the clavicle. The application of direct pressure over the medial end of the clavicle may also reduce the joint. Post reduction, the patient should be placed in a figure of * brace for 4-6 weeks. Despite successful reduction, the joint is usually remains unstable and redislocates in half of the cases.

The use of acute reduction of anterior dislocations is controversial as most end up redislocating and reduction techniques risk injury to mediastinal structures.

Posterior Dislocation

Posterior dislocations may be associated with life-threatening injuries to adjacent structures, including pneumothorax or injury to surrounding great vessels, trachea, or oesophagus.  Orthopedic consultation is necessary for closed or open reduction. Open reduction should be performed in the operating room.

Take Home

• Posterior dislocations necessitate prompt orthopaedic referral and looking for evidence of compression of retrosternal structures.
• Anterior dislocations often remains unstable post treatment and thus acute reduction is debatable. 

Further Reading:

• Rosen's Emergency Medicine - 7th Edition
• TIntinalli's Emergency Medicine - 8th Edition
• LIFTL
• ALiEM
• Morell, D. J., & Thyagarajan, D. S. (2016). Sternoclavicular joint dislocation and its management: A review of the literature. World Journal of Orthopedics, 7(4), 244–250. http://doi.org/10.5312/wjo.v7.i4.244

Posted by:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic