Knee Replacement · Patient question
Why Won’t My Knee Straighten After Knee Replacement?
Difficulty straightening the knee after replacement can be related to swelling, pain, quadriceps inhibition, protective positioning, preoperative stiffness, or developing tissue restriction. A physical therapist should assess the pattern rather than assuming one cause.
Why is knee straightening important?
A knee that reaches a useful straight position makes it easier to stand upright and move the body over the leg during walking. A persistent bent-knee posture can increase muscular effort and contribute to limping or fatigue.
The goal is not to force every knee to look identical. The therapist compares passive and active motion, walking, symptoms, prior motion, and surgical expectations.
What does a physical therapist check?
The therapist may examine swelling, kneecap and joint motion, pain response, hamstring or calf guarding, quadriceps activation, resting position, and the difference between how far the knee can be moved and how far the patient can actively hold it.
Walking and exercise technique matter too. Repeatedly resting with support directly under the knee or avoiding weight on the leg may reinforce a flexed position, while overly aggressive stretching may provoke more swelling in some patients.
When should I contact the surgeon?
Contact the care team if straightening is worsening, progress has clearly stopped, pain or swelling changes abruptly, or there are wound, fever, calf, or injury concerns. The timing of further medical decisions is the surgeon’s responsibility.
Common questions
Answers before you schedule.
Should I put a pillow under my knee?
Follow the surgical team’s instructions. Prolonged support that keeps the knee bent may work against extension goals, while temporary positioning for comfort or swelling may be advised differently.
Can weak quadriceps make the knee look bent?
Yes. A patient may have more passive straightening than active control. A therapist can distinguish this from a fixed motion limitation.
Should straightening exercises hurt?
Some discomfort can occur, but sharp, escalating, or prolonged symptoms should be reported. Exercise intensity should be individualized.
Clinical sources
References and further reading.
Schedule Physical Therapy
Have a question about your own situation?
General information cannot replace an evaluation. Tell PT365 your location and concern to ask whether one-on-one mobile outpatient physical therapy may be appropriate.