KNEE INJURIES WORKSHOP

Mark ClatworthyOrthopaedic Surgeon

Knee SpecialistMiddlemore Hospital

Overview Anatomy Refresher

How to diagnose and treat a meniscal tear, a ligament rupture and a patella dislocation

When should I take x rays of the knee and what should I take?

Practical on examination of the knee

Meniscal Tear

Mechanism of Injury

Typically a twisting injury on a loaded knee Often sudden pain Knee swells – variable time frame Mechanical symptoms – catching, locking,

clunking Can give a feeling of instability

Examination Findings

Effusion Springy block to extension if bucket

handle Focal joint line tenderness Pain on meniscal grinding Pain on loading and twisting

the knee

EffusionTense effusion is easily seen,

Moderate effusion – patella tapMild effusion - patella sweep

Meniscal Grind Test

Locked knee

Physical block

In young patient needs urgent meniscal repair

Don’t send to physiotherapistUrgent referral to orthopaedic surgeonWe will see the patient that week

Differential Diagnosis

Articular cartilage injury – unstable flap

Loose body

Stir up Osteoarthritis

Collateral Ligament Injury

Treatment Locked knee refer

RICE

Symptoms will typically improve over a 6 week period then plateau

Refer if persistent pain or mechanical symptoms

ACL Injury

History taking key to diagnosis

Acutely injured knees are painful and swollen making the examination difficult

The diagnosis normally lies in the history

ACL Injury Mechanism of injury

Normally a side stepping or pivoting manoeuver or an awkward landing

Often a non contact injury

The posterolateral knee subluxes

Patient will feel a pop and the knee gave way

ACL Rupture Patient usually presents with a

haemarthrosis

Knee may fell unstable with any twisting activity

Difficulty weightbearing due to bone bruising

The knee subluxes posterolaterally thus this area is usually tender

ACL Rupture

Patients often present with a fixed flexion deformity. Initially this is due to bone bruising.

A bucket handle tear typically occurs only with multiple giving way episodes

Examination Findings

Must examine both knees. Large variation laxity

Fixed flexion deformity, reduced flexion

Quads Wasting

Occurs very early. Up to 5% loss of muscle bulk a dayVery sensitive for a knee injury but not specific for a diagnosis

Ligament Examination The grading is determined by the increase in

laxity compared to the normal contralateral knee

AOSSM ClassificationGrade 1 - 0 – 5 mm increase in laxity Grade 2 - 5 – 10 mm increase in laxityGrade 3 - >10mm

ACL Examination Lachmann - anterior translation tibia

ACL Examination Lachmann – Big leg, small hands

ACL ExaminationAnterior drawer decreased by posterior horn of the menisci – less positive than

Lachmann

ACL Examination Pivot shift test- reproduces the sensation of

giving way. Lateral compartment subluxes

Exclude PCL Injury

Drop back seen with knee at 90°

Compare withother side

PCL Examination Posterior drawer

Acute Treatment RICE

Do not immobilize. No knee brace required if no collateral ligament injury.

Need to start on quads and knee extension exercises immediately

Can weightbear as tolerated Refer orthopaedic surgeon

and physio

Collateral Ligament Injuries

Mechanism of injuryValgus force – rupture MCLVarus force – rupture LCL

Patient presents with pain and instability with coronal movement

Collateral Ligament Examination

Palpate the ligament first.

MCL – Arises - medial femoral epicondyle Inserts – 6 - 8cm distally on the tibia

LCL - Arises from the lateral epicondyleInserts into the fibula

The LCL thus has more laxity than the MCL

Can palpated as a cord like structure when the knee is placed in a figure 4 position

Collateral Ligament Examination

Acute Treatment RICE

Do not immobilize. Short ROM brace if Grade II or III

Need to start on quads and ROM exercises immediately

Can weightbear as tolerated if knee feels stable

Refer orthopaedic surgeon and physio

Patella Dislocation

Mechanism of InjuryTypically twisting injury on a flexed knee or a direct blow

Patella may dislocate and stay there or self reduce

Examination findings

Haemarthrosis

Medial retinacular tenderness

Patella apprehension sign

Patella apprehension test

Acute Treatment Reduce dislocation RICE Aspirate if tense effusion Ensure there is no osteochondral fragment Immobilise in Zimmer splint – NO CASTS Refer to orthopaedic surgeon Refer to physio for static quads and straight

leg raising exercises Can weightbear as tolerated

Who should I X Ray?

Patients with a knee effusion

Unable to weight bear

Ligamentous injury

Patella dislocation

What X Ray’s should I take

Weight bearing AP

45º weight bearing PA

Lateral

Skyline

AP Pelvis if unsure about hip

Weight bearing X Rays Weight bearing X rays are critical

45° Weight bearing PA

Skyline patella

Weight Bearing X Rays Mandatory for ACC knee injuries

Orthopaedic surgeon can not get an ACC funded MRI scan without them

So if patient able to weightbear always order weightbearing knee X rays

Who should I refer immediately ?

Multi ligament knees

ACL & PCL avulsions

Locked knees

Patella dislocations with osteochondral fragments

Who should be referred to an Orthopaedic Surgeon?

All patients with suspicion of a- ligament tear- meniscal injury- patella dislocation

Who should be referred to the physiotherapists?

Patella dislocations

Cruciate ligament injuries

Collateral ligament injuries

No meniscal tears

Who should I aspirate? Only those with painful tense haemarthrosis. I aspirate very few Aspirate superio-lateral with a large >= 16

gauge angiocath.Inject Xylocaine with adrenalineExamine the knee after 5 minutes

If unsure refer

KNEE EXAMINATION DEMONSTRATION

http://www.acc.co.nz/for-providers/clinical-best-practice/practical-workshops/WPC090892