Knee Ankylosis C&P Exam Prep

Knee Flexion Range of Motion (Active)

What it measures: How far you can actively bend your knee toward your buttocks; normal is 0-140 degrees

What to expect: Examiner will ask you to bend your knee as far as possible while seated or standing. A goniometer will measure the angle. Perform this movement as you would on a typical or bad day - do not push through severe pain to demonstrate a false maximum.

Pain considerations: If pain stops motion before the anatomical limit, inform the examiner: 'I'm stopping here because of pain, not because the joint won't go further.' This triggers the DeLuca pain-on-motion analysis and may entitle you to a lower (more restricted) effective ROM for rating purposes.

Knee Extension Range of Motion (Active)

What it measures: How far you can actively straighten the knee; normal is 0 degrees (full extension)

What to expect: Examiner will ask you to straighten your knee as fully as possible. A fixed knee in ankylosis typically cannot achieve this movement. Any fixed flexion contracture should be noted precisely in degrees.

Pain considerations: Extension attempts that are stopped by pain rather than mechanical block should be distinguished and communicated clearly to the examiner.

Passive Range of Motion

What it measures: How far the examiner can move your knee without your muscular effort; reveals true joint mobility versus muscle guarding

What to expect: Examiner will gently move your knee through flexion and extension while you relax your leg muscles completely. This is a critical measurement - if passive ROM exceeds active ROM, the examiner should note the difference and the reason (pain, weakness, incoordination).

Pain considerations: Pain during passive motion should be reported verbally: 'I feel pain when you move it there.' This is documented as evidence of pain on passive motion, a DeLuca factor.

Weight-Bearing vs. Non-Weight-Bearing ROM

What it measures: Whether the angle of fixation or available motion differs when you are standing versus seated or lying down

What to expect: Examiner should test ROM in both positions per Correia requirements. Weight-bearing testing may reveal additional functional impairment not apparent in non-weight-bearing positions.

Pain considerations: Standing on an ankylosed knee often produces radiating pain, altered gait mechanics, and compensatory hip/back pain - describe all of these.

Repetitive Use Testing (3 Repetitions)

What it measures: Whether ROM decreases, pain increases, or fatigue develops after repeated movement attempts - core DeLuca factor

What to expect: Examiner may ask you to perform the same knee motion three times in succession. After the third repetition, they should re-measure to see if ROM has decreased or symptoms have increased.

Pain considerations: Post-repetition pain is a legitimate ratable DeLuca factor. Do not minimize it. Example: 'After bending it three times, I have a sharp burning pain on the inner side of my knee that takes about 20 minutes to calm down.'

Circumferential Thigh/Calf Muscle Atrophy Measurement

What it measures: Difference in muscle circumference between the affected and unaffected leg, indicating disuse atrophy from compensating for the ankylosed knee

What to expect: Examiner will measure around your thigh and possibly calf at a standardized point using a tape measure. Significant atrophy (>2 cm difference) documents functional disuse.

Pain considerations: Atrophy often accompanies weakness and fatigue - describe difficulty bearing weight and how quickly the leg tires.

Leg Length Discrepancy Measurement

What it measures: Whether the ankylosed knee has caused a functional or actual leg length difference that affects gait

What to expect: Examiner measures from bony landmarks (anterior superior iliac spine to medial malleolus) on both legs. Discrepancy may result from the fixed angle of the ankylosed joint.

Pain considerations: Leg length discrepancy causes compensatory mechanics that produce secondary pain - always link these to your knee ankylosis.

60%

Knee ankylosis that is extremely unfavorable - fixed in flexion at an angle of 45 degrees or more. This position is severely functionally limiting because the knee is significantly bent and cannot support normal weight-bearing or gait.

From 38 CFR: DC 5256: Extremely unfavorable, in flexion at an angle of 45- or more - 60%

50%

Knee ankylosis fixed in flexion between 20 and 45 degrees. The joint is fused in a moderately unfavorable position - functional weight-bearing is severely impaired and compensatory positioning is required.

From 38 CFR: DC 5256: In flexion between 20- and 45- - 50%

40%

Knee ankylosis fixed in flexion between 10 and 20 degrees. The joint is fused in a moderately unfavorable position that still significantly impairs function, particularly activities requiring knee flexion.

From 38 CFR: DC 5256: In flexion between 10- and 20- - 40%

30%

Knee ankylosis in a favorable angle - fixed in full extension (0 degrees) or slight flexion between 0 and 10 degrees. Although this is the 'best' position for ankylosis, significant functional disability remains because the knee cannot flex at all.

From 38 CFR: DC 5256: Favorable angle in full extension, or in slight flexion between 0- and 10- - 30%

Pain

How to describe it: Describe pain by location (front of knee, behind knee, inner/outer side), character (sharp, burning, aching, throbbing), intensity on a 0-10 scale on both average days and worst days, what triggers it, what relieves it, and how long it lasts after activity.

Example: On my worst days, which happen at least two to three times per week, the pain starts at an 8 out of 10 just standing up from a chair. It's a deep aching pain on the inner side of my fixed knee that spreads down my shin and up into my hip. It makes me stop what I'm doing and sit for at least 30 minutes before I can move again.

Examiner listens for: Specific anatomical location, numerical rating, functional triggers, duration after provocation, whether pain occurs at rest versus only with activity, and whether pain interrupts sleep.

Avoid: Saying 'it hurts sometimes' or 'the pain isn't too bad' without quantifying. Do not minimize pain to appear tough - the examiner needs accurate information to document disability. Avoid saying 'I manage fine' if you have adapted your life around the limitation.

Functional Limitation from Ankylosis

How to describe it: Describe every specific activity the fixed knee prevents or limits: sitting in standard chairs, riding in vehicles, ascending/descending stairs, kneeling, squatting, getting up from the floor, prolonged standing, walking distance, and balance. Be concrete and specific with distances and times.

Example: Because my knee is locked, I cannot bend it to sit in a normal chair without my leg sticking straight out. At work I need a special chair with a leg rest, and even then after 45 minutes I have to get up and move because the pressure on my hip becomes unbearable. I can walk no more than half a block before the compensatory pain in my lower back makes me stop.

Examiner listens for: Specific activities affected, adaptive strategies the veteran has adopted, distances and time tolerances, interference with work, and daily living limitations.

Avoid: Saying 'I just avoid activities that bother it' without describing what those activities are. The examiner documents what you report - if you don't say it, it doesn't get recorded.

Fatigue and Lack of Endurance (DeLuca Factor)

How to describe it: Describe how quickly your leg fatigues with use, how the fatigue manifests (weakness, heaviness, burning), and how long recovery takes. Explain how fatigue from the ankylosed knee limits work, exercise, and daily activities.

Example: After walking for about 10 minutes, my thigh muscle becomes so fatigued that my whole leg feels heavy and unstable. I have to sit down for 20 to 30 minutes before I can walk again. By midday I'm exhausted from compensating with my hip and back, and I often have to lie down for an hour in the afternoon just to manage the rest of the day.

Examiner listens for: Onset of fatigue relative to activity level, recovery time required, impact on occupational activities, and whether fatigue is worse on certain days.

Avoid: Not mentioning fatigue at all because you think only pain matters. Fatigue is an explicit DeLuca factor that the examiner must document and that can increase your effective rating beyond what measured ROM alone shows.

Weakness (DeLuca Factor)

How to describe it: Describe objective weakness - difficulty lifting items with the affected leg, inability to rise from seated or squatting positions without using arms, leg giving way or buckling, and any documented muscle atrophy in your thigh.

Example: My quadriceps on the affected leg are noticeably smaller than the other side - my pants fit differently. I cannot push off that leg when getting up from a low chair without using both arms on the armrests. On bad days, the leg feels like it will buckle when I step off a curb.

Examiner listens for: Specific functional demonstrations of weakness, documentation of atrophy, any history of falls or near-falls from the weakened leg, and occupational impact.

Avoid: Describing weakness only vaguely as 'it feels weak.' Quantify: 'I cannot rise from a standard chair without using my arms' is far more useful than 'my leg is weak.'

Flare-Ups (DeLuca Factor)

How to describe it: Describe episodes when your condition worsens beyond baseline: frequency (times per week/month), duration (hours or days), what triggers them (weather, activity, prolonged standing), what symptoms worsen (pain, swelling, stiffness), and how flare-ups affect your ability to work and function.

Example: I have severe flare-ups two to three times a week, usually after any activity involving prolonged standing or when the weather changes. During a flare-up, my pain jumps to 9 out of 10, my knee and hip swell, and I am completely unable to work or perform household tasks for 24 to 48 hours. I have missed work multiple times because of these episodes.

Examiner listens for: Frequency and predictability of flare-ups, what provokes them, duration of each episode, specific functional losses during flare-ups, and any documentation in medical records.

Avoid: Describing your condition only on a typical day when the examiner asks how you are doing. Proactively volunteer flare-up information: 'Today is actually a relatively good day - on my bad days, which happen [X] times per week, the situation is significantly worse.'

Incoordination and Gait Disturbance (DeLuca Factor)

How to describe it: Describe your altered gait pattern caused by the fixed knee - swinging the leg out (circumduction), leaning to one side, inability to walk heel-to-toe, difficulty with uneven terrain, and any falls or near-falls.

Example: Because my knee won't bend, I have to swing my whole leg out in a circular motion to walk, which means my hip, lower back, and opposite knee take all the impact. I cannot walk on grass, gravel, or any uneven surface without serious fall risk. I have fallen twice in the past year because my fixed leg caught on something while I was walking.

Examiner listens for: Observable gait abnormalities during the exam, patient-reported fall history, balance difficulties, and impact on safe ambulation in work and daily life environments.

Avoid: Not mentioning falls or near-falls. These are critically important for documenting functional loss, safety risk, and the need for assistive devices.