A patellectomy is the surgical removal of the kneecap, either in part or in full. Surgeons turn to it when a fracture has shattered the patella into too many fragments to piece back together, or when conditions like severe infection or a bone tumor make preserving the kneecap impractical. Although advances in hardware and fixation techniques have made it far less common than it once was, patellectomy remains a valid treatment for certain injuries, particularly the heavily comminuted fractures that account for a sizable share of all patellar breaks.
Why the Kneecap Matters So Much
The patella is a small, shield-shaped bone embedded in the tendon that connects your quadriceps muscles to your shinbone. Its main job is mechanical leverage. By sitting in front of the knee joint, it pushes the quadriceps tendon farther from the joint’s center of rotation, giving your thigh muscles a better “lever arm” to straighten your leg. At low angles of knee bend, the kneecap actually amplifies quadriceps force so that the pull transmitted through the patellar tendon exceeds the force the muscle itself generates.1PubMed Central. The effective quadriceps and patellar tendon moment arms relative to the tibiofemoral finite helical axis That leverage advantage is why losing the patella has real consequences for leg strength and why surgeons avoid removing it whenever they can.
Beyond force multiplication, the kneecap also protects the front of the knee joint from direct blows and helps distribute compressive loads across the groove at the end of the thighbone. Remove it, and you lose both the shield and the lever. The trade-off only makes sense when the alternative is a kneecap too damaged to function at all.
When Patellectomy Becomes Necessary
Patellar fractures make up roughly half a percent to one and a half percent of all skeletal injuries and tend to occur in adults between 30 and 60 years old, often from a direct blow to the knee such as a dashboard impact during a car collision. Most of these fractures can be repaired with screws, wires, or plates. Patellectomy enters the picture when the break is too severe for that kind of reconstruction.
The most common indication is a comminuted fracture where the bone has splintered into many small pieces with no large fragments stable enough to bolt together. A partial patellectomy is considered when the shattering is confined to one pole of the kneecap, usually the lower end, while enough of the remaining bone can be preserved and the patellar tendon reattached to it. Total patellectomy is reserved for rarer situations: fractures so badly comminuted that no usable fragment remains, cases of failed prior internal fixation, or patellar osteomyelitis (deep bone infection) that has destroyed the bone.2PubMed Central. Patellectomy, an old treatment in patellar fracture which is still alive: A case report
Less frequently, patellectomy is performed for aggressive bone tumors of the patella or for isolated patellofemoral arthritis that has failed every conservative treatment. When osteoarthritis is limited to the undersurface of the kneecap and the groove it rides in, removing the patella can relieve grinding pain that nothing else has touched. All patients in one long-term surgical series experienced pain relief after patellectomy for arthritis, and those whose disease was confined to the patella itself fared better than those who also had damage in the trochlear groove.3PubMed Central. Patellectomy for osteoarthritis: a new tension preserving surgical technique to reconstruct the extensor mechanism with retrospective review of long-term follow-up
Partial Versus Total Patellectomy
Partial patellectomy removes the shattered portion of the kneecap while preserving as much healthy bone as possible. The patellar tendon is then reattached to the remaining fragment so the extensor mechanism stays intact. Surgeons generally prefer this approach because it keeps some of the kneecap’s leverage and protective function in place. However, the amount of bone removed matters a great deal. Laboratory studies have shown that excising up to about 40 percent of the patella causes changes in joint contact that can be partially offset by careful tendon reattachment, but removing 60 percent or more cuts the remaining contact area to less than half of normal regardless of how the tendon is repositioned.4Journal of Bone and Joint Surgery – Series A. Effects of partial patellectomy and reattachment of the patellar tendon on patellofemoral contact areas and pressures In practical terms, there is a tipping point beyond which saving a sliver of bone offers little advantage over removing the whole thing.
Total patellectomy takes out the entire kneecap. The quadriceps tendon and patellar tendon are then sewn together, recreating a continuous band across the front of the knee. One long-term follow-up study comparing total patellectomy with tension-band-wire fixation found that the two groups had statistically similar results in range of motion, muscle torque, and patient-reported knee scores after 10 to 20 years, though total patellectomy did take significantly less operating time.5PubMed Central. Comparison of total patellectomy and osteosynthesis with tension band wiring in patients with highly comminuted patella fractures: a 10–20-year follow-up study That finding is somewhat surprising, given the traditional view that losing the entire kneecap leads to clearly worse function. It suggests that in severely comminuted fractures, where the fixation itself is imperfect, the two roads end up in roughly the same place.
Still, the broader evidence indicates that complete removal generally produces more quadriceps weakness and greater ligament instability than partial removal.6Clinical Orthopaedics and Related Research. The effect of patellectomy on knee function This is why surgeons default to partial patellectomy whenever the fracture pattern allows it.
Reinforcing the Extensor Mechanism
One of the most consistent findings in the surgical literature is that how the extensor mechanism is reconstructed matters at least as much as how much bone is removed. A systematic review covering more than 1,400 knees found that the median rate of good or excellent outcomes jumped substantially when the extensor mechanism was reinforced during the procedure, compared with patellectomy alone.7PubMed. Total patellectomy in knees without prior arthroplasty: a systematic review Reinforcement typically means pulling local tissue over the repair site, using a fascial flap, or wrapping the tendon junction with additional material to spread the load and prevent the repair from stretching out over time.
Newer techniques have expanded the toolkit. In cases involving bone tumors, surgeons have used composite augments combining synthetic polypropylene mesh with donor fascia lata tissue to replace both the bone and the surrounding soft-tissue envelope in a single construct.8PubMed Central. Reconstruction of the Extensor Apparatus Using a Hybrid Augment with Polyethylene Mesh and Fascia Lata Allograft: Report of a Case with Patellar Gigant Cell Tumor of the Bone For younger patients who have failed a partial patellectomy and need their extensor mechanism rebuilt more completely, donor bone-patellar-tendon-bone grafts have been used to replace the missing kneecap and tendon segment. One such patient reached full range of motion and returned to sports within six months.9PubMed. Extensor mechanism reconstruction: a novel technique for bone patella allograft post partial patellectomy failure These are specialized procedures performed in select centers, but they represent a growing recognition that simply removing the kneecap and hoping the tendon holds is not always enough.
What Recovery Looks Like
Recovery after patellectomy is measured in months, not weeks, and the first priority is protecting the repaired tendon while gradually restoring motion and strength. Most protocols start with the knee in a brace or splint locked in extension to prevent the healing tendon from being overstressed. Gentle, passive bending exercises begin within the first few weeks, and active strengthening of the quadriceps ramps up as the tissue heals.
The realistic expectation is that you will regain most of your range of motion but lose some quadriceps strength. One long-term study reported that patients retained about 75 percent of normal extensor strength on the operated side, alongside 88 percent overall patient satisfaction and no ligament instability.10PubMed. Patellectomy: results of a long-term follow-up Patients in the comparative study mentioned earlier achieved an average range of motion of roughly 120 degrees on the injured side after total patellectomy, which is close to the approximately 127 degrees measured on their uninjured side.5PubMed Central. Comparison of total patellectomy and osteosynthesis with tension band wiring in patients with highly comminuted patella fractures: a 10–20-year follow-up study That gap is noticeable in a clinical measurement but is rarely the thing patients complain about most. Strength and stamina tend to be the bigger day-to-day issues.
The systematic review of total patellectomy outcomes found an overall complication rate of about 20 percent, though more than half of those were calcifications that formed in the soft tissues and did not necessarily cause symptoms.7PubMed. Total patellectomy in knees without prior arthroplasty: a systematic review The mean percentage of outcomes rated good or excellent across the studies in that review was roughly 69 percent, with a wide range depending on surgical technique and patient selection.
How Walking Changes Without a Kneecap
Your body adapts to a missing patella in subtle but measurable ways. Gait analysis of patellectomy patients revealed that about 80 percent fired their calf muscles earlier than normal during each stride, before the heel even hit the ground.11PubMed. Gait and functional analysis of patients following patellectomy Researchers interpret this as a compensatory strategy: by stiffening the ankle early, the calf helps stabilize the knee at heel strike, reducing the demand on the weakened quadriceps. Patients who scored well on functional tests walked with a near-normal pattern, while those with poorer results showed more pronounced gait abnormalities.
This compensation works well enough for level walking and most daily activities, but it can fall short during activities that load the knee heavily in a bent position, like climbing stairs, rising from a low chair, or squatting. Those are the movements where the patella’s leverage boost is missed the most. Targeted quadriceps strengthening during rehabilitation helps narrow the gap, though most people will always feel some difference on the operated side during demanding tasks.
Long-Term Joint Health After Patellectomy
One of the less-discussed consequences of patellectomy is an increased risk of osteoarthritis in the rest of the knee joint over time. An arthroscopic study of patients who had previously undergone patellectomy found cartilage damage in 15 of the 16 knees examined, concentrated in the inner (medial) compartment and the trochlear groove. The severity of that cartilage damage correlated with how many years had passed since the patellectomy, not with the patient’s age, and no other risk factors for arthritis could be identified.12PubMed. Patellectomy and osteoarthritis: arthroscopic findings following previous patellectomy The findings suggest that removing the kneecap changes the way forces travel through the joint in a way that accelerates cartilage wear over years and decades.
This matters because it means some patellectomy patients will eventually develop knee arthritis severe enough to need a total knee replacement. That second surgery is more complex than a standard knee replacement because the absent patella changes the biomechanics the prosthesis has to work with. A meta-analysis of case-control studies confirmed that post-patellectomy patients form a distinct subset who can develop disabling knee arthritis requiring total knee arthroplasty.13Knee. Total knee arthroplasty after patellectomy: a meta-analysis of case-control studies A review of the literature on this population found an overall complication rate of 34 percent in post-patellectomy knee replacement patients, and the odds of achieving an excellent or good result were about 30 percent lower than in patients who still had their kneecaps.14PubMed Central. Total Knee Arthroplasty After a Previous Patellectomy: A Case Report With a Six-Month Follow-Up and a Review of the Literature The reduction in range of motion was small enough to be clinically minor, but the higher rates of instability, infection, and stiffness are real concerns.
Protecting the Knee After the Kneecap Is Gone
One complication specific to post-patellectomy knees is rupture of the patellar tendon, which can happen months or years after surgery. Without the kneecap serving as a bony anchor and stress-diffuser, the tendon operates under altered mechanical conditions and may be more vulnerable to failure, especially during sudden forceful movements. When this happens, the knee’s extensor mechanism is broken and the person cannot straighten the leg against gravity. Surgical repair typically involves stitching the torn tendon ends together and sometimes reinforcing the site with graft material.15PubMed Central. Reconstruction of Acute Patellar Tendon Rupture after Patellectomy Careful, graduated rehabilitation after such a repair is essential because the tendon has already proven itself vulnerable.
For people living without a kneecap, the practical takeaway is that quadriceps conditioning is not optional. Strong thigh muscles compensate for the lost mechanical advantage, protect the remaining soft tissues from overload, and appear to correlate with better gait patterns. Low-impact activities that build quad strength without heavy eccentric loading, like swimming and stationary cycling, tend to be safe choices. High-impact sports and deep-squatting movements carry higher risk and are generally discouraged, though individual tolerance varies.
Why Patellectomy Still Has a Role
Patellectomy is sometimes characterized as an outdated procedure, but that characterization misses the reality that comminuted fractures, which make up an estimated 55 percent of all patellar fractures, still present surgeons with bone that cannot always be meaningfully reconstructed.2PubMed Central. Patellectomy, an old treatment in patellar fracture which is still alive: A case report Modern fixation options like tension band wiring, cannulated screws, and basket plates have narrowed the field considerably, and most patellar fractures today are treated with hardware. But when the fragments are too small, too numerous, or too infected for fixation to succeed, patellectomy remains the fallback. It is less a first-choice treatment than a reliable last resort, and knowing when to reach for it is part of the orthopedic surgeon’s skill set.
Bipartite Patella and Other Confounders
Not every painful kneecap problem that ends in surgery is a fracture. A bipartite patella, a developmental variant where a portion of the kneecap never fully fuses to the main bone, can cause chronic pain in physically active people. When conservative measures fail, the symptomatic fragment can be excised, which is essentially a small partial patellectomy. Long-term follow-up of young adults who underwent this procedure showed excellent functional scores at an average of 15 years, with minimal arthritic changes.16PubMed Central. Excision of painful bipartite patella: good long-term outcome in young adults The fragment being removed in these cases is typically small compared with the total patella, so the biomechanical hit is minor. It is worth knowing about mainly because it shows up on imaging and can be mistaken for a fracture fragment, potentially changing the conversation about whether more aggressive surgery is needed.
This highlights a broader point: patellectomy is not a single uniform procedure but a spectrum, from shaving off a small accessory fragment to removing the entire bone. Where you fall on that spectrum determines the likely impact on strength, gait, and long-term joint health. The conversation between surgeon and patient should include not just whether to remove bone, but how much, how the tendon will be secured, and what the rehabilitation plan looks like afterward.