• Hip and knee surgery
• Traumatology

Background and aims
Total Knee Arthroplasty (TKA) is a well-established procedure for treating osteoarthritis (OA) and other knee disorders by replacing the knee joint. While TKA has high success rates, complications can still occur. One of the most serious complications or injuries after a TKA is a periprosthetic knee fracture (PPKF), a fracture near or associated with the TKA implant, affecting the femur, patella, or tibia. Though rare, PPKFs are disabling for patients, and treatment often requires advanced surgical skills. Despite their clinical significance, little is known about PPKFs.
This thesis aims to fill these gaps using mixed-method research to investigate PPKF risks, identify associated factors, and evaluate clinical and patient-reported outcomes to improve care for affected patients.

Studies
In the register based study 1 we analyzed the risk and risk factors for PPKF in standard primary TKA patients with OA who had minimally (cruciate retaining without a femoral box cut) or posterior stabilized TKA. We found a 10-year risk of 1.7%, with 1.5% in the femur, 0.2% in the patella, and 0.2% in the tibia. Significant risk factors included ipsilateral hip arthroplasty, female sex, osteoporosis, age 80+, uncemented TKA, and Charlson Comorbidity Index score ≥3.

In the exploratory qualitative study 2 we investigated patients' experiences after surgical treatment of a distal femur PPKF through interviews. We identified three key themes of important experiences to the patients: (1) Patient expectations of recovery, (2) Patient concerns—leading to a desire for follow-up and information, and (3) The impact of recovery on independence and social life, each explored through subthemes. The study highlights the prolonged and challenging recovery, often causing frustration and isolation. Addressing these issues requires clear communication and realistic expectation-setting for patients.

In the questionnaire based study 3 we assessed patient-reported outcomes (PRO) on knee function, quality of life, pain, and treatment satisfaction 1–4 years after PPKF and compared it to a matched control group of uncomplicated TKA patients. The PPKF patients reported a worse scores across all parameters compared to the control group. The patients completing the questionnaires 3-4 years after their PPKF reported better scores compared to those completing the questionnaires 1-2 years after the PPKF, indicating a prolonged recovery. Operatively treated PPKF patients had worse PRO scores than those treated non-operatively, particularly after patellar PPKFs, likely reflecting fracture severity rather than treatment effects.

In the register-based study 4 we examined the reoperation risk after initial treatment of the PPKF according to fracture site and treatment approach. The overall two-year reoperation risk was 20%. Operatively treated PPKFs had a higher reoperation risk across all fracture locations. The highest risks were observed in operatively treated patellar and tibial PPKFs, with reoperation rates of 46% and 36%, respectively, while the lowest risk was seen in non-operatively managed patellar PPKFs at 9%.

Conclusions
PPKF is a rare but serious complication following primary TKA. Although it occurs in just 1.7% of cases within 10 years, it greatly impacts the lives of those affected. Both qualitative interviews and PRO scores show that recovery from PPKF is prolonged. Operatively treated PPKFs have poor outcomes, with low PRO scores and a high reoperation risk, especially operatively treated patella PPKFs. As fracture severity is not accounted for in the studies, this thesis is more explorative and aims to enhance understanding and patient expectation management, rather than recommend specific treatment approaches for PPKFs.

Download afhandlingen

Artikler inkl. DOI
1. Risk and Epidemiology of Periprosthetic Knee Fractures After Primary Total Knee Arthroplasty: A Nationwide Cohort Study. DOI: 10.1016/j.arth.2024.05.033
2. Patient experiences after surgically treated periprosthetic knee fracture in the distal femur - an explorative qualitative study. DOI: 10.1016/j.ijotn.2025.101194
3. Patient-reported outcome 1 to 4 years after periprosthetic knee fracture: a nationwide cross-sectional matched study. DOI: 10.2340/17453674.2025.43083
4. Reoperations After Operatively and Non-Operatively Treated Periprosthetic Knee Fractures: A Nationwide Study on 1,931 Fractures After Primary Total Knee Arthroplasty. DOI: 10.1016/j.arth.2024.11.010