Keywords : Knee osteoarthritis

Factors that Influence the Range of Motion Following Primary Total Knee Arthroplasty

Iraqi Postgraduate Medical Journal, 2020, Volume 19, Issue 1, Pages 60-67

Total knee arthroplasty is now practiced increasingly. Arthroplasty is considered successful if
the knee is stable, painless with good range of motion.
To evaluate the importance of different factors that might affect the success rate of total arthroplasty
in knee osteoarthritis
Patients with osteoarthritic knees admitted to Basrah center of joint replacement (Basrah Teaching
Hospital) during the period from January 2017 to October 2018, for total knee replacement were
enrolled in the study. Factors that can affect post-operative range of motion were studied. These
involved factors related to patients (such as age, gender, body mass index, comorbidities, side of
diseased knee, knee functional score, and range of motion), and those related to the operative
procedure(duration of operation, use of tourniquet, size of femoral and tibial components, and
the type of polyethylene spacer). The amount of postoperative blood in the drain was also recorded.
The follow up period was for up to one year after the surgical operation.
Seventy five patients were included in the study, 60 females and 15 males who constituted (80%,
20%) respectively. The mean age was (59.20±7.05 years), ranged between (45 - 71 years). The mean
BMI of the patients was (26.52 ± 2.67). The tibial size ranged from 3 to 7 with mean
(5.08±1.39).The mean pre and post-operative ROM (after one year follow up) was (110.20±20.25)
and (116.46±6.76) respectively. The functional knee score (Lysholm score) increased from
(50.40±14.67) to (79.48±9.75) post operatively. Fifty two percent of the patients were right sided
knee and 48% of them were left sided. There was no significant statistical correlation between knee
side and range of motion postoperatively. Correlation was also not significant between associated
diseases, gender and post-operative range of motion. Patients with normal BMI had better
postoperative ROM than over weight and obese patients with mean ROM (120.17±5.49,
115.0±10.28 and100.0±16.92) respectively. There was significant negative statistical correlation
between the age and the post-operative range of motion. There was a significant negative correlation
between post-operative range of motion, polyethylene spacer, and size of tibial and femoral
components used. No correlation was found between the time of operation and postoperative range
of motion; however, the latter was negatively correlated with the amount of blood in the drain.
Postoperative range of motion after primary total knee arthroplasty in osteoarthritis of the knee
joint seems to be mostly affected by preoperative range of motion and BMI. Younger patients tend
to have a better postoperative range of motion, while larger size of the components of arthroplasty
are associated lower post-operative range of motion.