The goal of this observational study is to assess the prevalence of radiographic knee osteoarthritis and to report medium and long term functional outcomes secondary to tibia plateau fractures. The second aim was to investigate whether there were any risk factors associated with these outcomes.

1. The study population consists of patients from the Swedish region of Norrbotten (northern part of Sweden) who had undergone TPF between the years of 2001 and 2015.
2. All patients are evaluated radiographically.
3. Condition-specific scores are assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS). General health related quality of life are assessed by the EuroQol 5-Dimension 5-level (EQ-5D-5L) tool.
4. All patients are examined clinically.
5. The relationship between the development of radiographic OA in patients who had undergone TPF and such potential factors as gender, age, body mass index (BMI), fracture pattern or method of fracture treatment is being assessed.
6. The data from the Swedish Fracture Register and the Swedish Arthroplasty Register are used in order to follow the long-term results.

Inclusion Criteria:

• Patients from the region of Norrbotten (northern part of Sweden) who underwent tibial plateau fracture between the years of 2001 and 2015

Exclusion Criteria:

• Death without bilateral weighted X-ray minimum 5 years post injury
• Open growth plate in distal femur and/or proximal tibia
• Extraarticular or isolated eminentia fracture
• OA prior to injury
• Having a rheumatic disorder involving joints
• Earlier and/or later severe injury to the index knee
• Having cognitive disorders disqualifying from the study

The study group consists the subjects who underwent tibial plateau fracture and that could be identified by a computer-assisted search of the local medical journal database Vård Administrativt System (VAS), using the ICD-10 diagnostic codes for proximal tibia fracture (open and closed) (S82.1, S82.8 and S 82.9).