Examination and Anatomy

Record injury mechanism, symptom course, gait, swelling, and range of motion first. Identify which movements produce tenderness, locking, or snapping, and compare with the opposite side. These findings define the questions to ask of imaging.

Knee pain may not be explained by intra-articular pathology alone. Assess the hip, spine, neurovascular status, and surrounding soft tissue as needed. MRI is interpreted with examination; not every finding causes the symptoms.

Record the history systematically, including not only pain location but also onset, injury, changes in loading, speed of swelling, locking and giving way, and response to previous treatment. Observation assesses gait, alignment, and muscle atrophy; ROM assessment distinguishes active from passive motion and documents the endpoint. Check whether the structure suggested by tenderness or a positive test corresponds to the movement that actually troubles the patient, and define the question for imaging.

Acute major swelling, inability to bear weight, changes in foot sensation, motor function or circulation, and fever with marked warmth require different priorities from routine pain assessment. In particular, knee dislocation requires neurovascular assessment even if it has reduced spontaneously and now appears normal. In nonacute pain, also consider the hip, spine, neurovascular structures, and surrounding tendons rather than fixing the diagnosis on MRI findings alone.

Lachman and pivot shift provide information about different directions of instability. During valgus and varus stress testing, the structures under tension vary with flexion angle. Record opening and the endpoint together.

Interpret posterior sag, posterior drawer, and the dial test in relation to possible combined injuries. Dial-test results at 30 and 90 degrees alone do not establish a particular structural injury. Combine contralateral comparison, examination position, other tests, and imaging.

Ligament examination is a measurement that includes direction, angle, and endpoint. Anterior translation on Lachman testing and rotational subluxation on pivot-shift testing provide different functional information. In a PCL injury, examining anterior movement without recognizing posterior sag can make a different starting position appear to be an ACL problem. The structures involved in valgus and varus stress differ between extension and flexion, so document the angle and comparison with the opposite knee.

When combining the dial test and posterior drawer, consider the tibial starting position, hip rotation, ankle conditions, and guarding. Differences in external rotation at 30° and 90° alone do not establish a PLC or PCL injury. If acute pain limits examination, document the limitation and reassessment plan, and relate stress imaging and MRI to the anatomical injury. Peroneal nerve function and vascular status must also be recorded in a multiligament injury.

Gait shows loading responses that may not appear during examination on a couch. Begin with usual walking speed, walking aids, pain-related shortening of stance, limited extension, and varus or valgus thrust. A thrust is a transient increase in varus or valgus during loading and differs from static limb alignment. Record the symptomatic side and timing of the movement, and repeat observation at a consistent distance and speed when needed.

Varus thrust was associated with medial osteoarthritis progression in observational cohorts, but the sign alone cannot determine an individual's progression rate or need for surgery. Relate bony alignment, intra-articular laxity, pain avoidance, and strength to examination and imaging. Visually observed thrust and the adduction moment calculated during gait analysis are different measurements. If observation is unclear, reassess gait and compare stress examination with long-leg imaging to narrow the cause of dynamic alignment change.

Functional assessment uses everyday tasks such as rising, fast walking, and stair climbing. The 30-second chair-stand, 40 m fast-paced walk, and stair-climb tests form the OARSI core set; timed up-and-go and a 6-minute walk may be added when appropriate. Standardize chair height, arm use, aids, handrails, footwear, and instructions. Record pain, movement quality, and reasons for stopping alongside time or repetitions. When fall risk is present, prioritize safety and modify the assessment.

Pelvic or trunk compensation and inward knee movement during single-leg support or step-down suggest the need to assess strength, balance, and pain control together; they do not diagnose a specific ligament or cartilage injury. Bilateral weakness can also make side-to-side symmetry misleading. Performance tests and patient-reported function capture different aspects, and high reliability does not ensure responsiveness to change in every population. Compare standardized performance with symptoms and activity goals during follow-up.

An examination through anterior portals may not fully show structures such as the medial meniscal posterior horn or the PCL tibial attachment. If a lesion suspected on MRI or examination is not visible arthroscopically, absence of pathology is distinguished from insufficient visualization. A systematic inspection sequence and the reason for additional posterior-compartment assessment are planned before surgery.

Anterior portal placement is linked to safe visualization and an instrument route to the target rather than a fixed skin distance. Needle localization under arthroscopic observation tests the route and checks for interference with cartilage and the meniscus. Forceful insertion when an instrument does not pass can turn an exposure problem into cartilage damage, so position, direction and exposure are reassessed.

Posteromedial and posterolateral portals require attention to structures including branches of the saphenous nerve and the common peroneal nerve. Cadaveric studies published in 2011 showed that direct visualization, the external anatomical soft spot and knee flexion affect the distance between portals and nerves. Ninety-degree flexion helped under those study conditions, but the reported safety zones and distances do not guarantee safety in every patient's anatomy.

A posterior transseptal approach expands visualization and working access to the posterior compartments but involves work close to popliteal neurovascular structures. Before adding a portal, the structures to visualize, instrument direction and relationship to the posterior capsule are defined. If visualization and a safe route are inadequate, the approach is reassessed while maintaining both complete lesion assessment and protection of surrounding structures.