title: Knee joint effusion following ipsilateral hip surgery.
abstract: OBJECTIVE
  To correlate patellar reflex inhibition with sympathetic knee joint effusion.
  
  
  METHODS
  65 women and 40 men aged 45 to 75 (mean, 65) years underwent hip surgery. The surgery entailed dynamic hip screw fixation using the lateral approach with reflection of the vastus lateralis for pertrochantric fractures (n = 49), and hip hemiarthroplasty or total hip replacement using the Watson-Jones approach (n = 38) or hip hemiarthroplasty using the posterior approach (n = 18) for subcapital femoral fractures (n = 28) or osteoarthritis (n = 28). Knee joint effusion, patellar reflex, and thigh circumference were assessed in both legs before and after surgery (at day 0.5, 2, 7, 14, 30, and 45). Time-sequence plots were used for chronological analysis, and correlation between patellar reflex inhibition and knee joint effusion was tested.
  
  
  RESULTS
  In the time-sequence plot, the peak frequency of patellar reflex inhibition (on day 0.5) preceded that of the knee joint effusion and the thigh circumference increase (on day 2). Patellar reflex inhibition correlated positively with the knee joint effusion (r = 0.843, p = 0.035). These 2 factors correlated significantly for all 3 surgical approaches (p < 0.0005). All 3 approaches were associated with patellar reflex inhibition on day 0.5 (p = 0.033) and knee joint effusion on day 2 (p = 0.051).
  
  
  CONCLUSIONS
  Surgical trauma of the thigh may cause patellar reflex inhibition and subsequently knee joint effusion.
authors.affiliation: 1st Orthopaeidc Department, General Hospital G Papanikolaou, Exoxi, Thessaloniki, Greece. an.christodoulou@gmail.com
authors.forename: A G
authors.initials: AG
authors.lastname: Christodoulou
authors.forename: P
authors.initials: P
authors.lastname: Givissis
authors.forename: P D
authors.initials: PD
authors.lastname: Antonarakos
authors.forename: G E
authors.initials: GE
authors.lastname: Petsatodis
authors.forename: I
authors.initials: I
authors.lastname: Hatzokos
authors.forename: J D
authors.initials: JD
authors.lastname: Pournaras
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D015331:Cohort Studies; D005260:Female; D006620:Hip Fractures / Q000150:complications / Q000601:surgery*; D006801:Humans; D006833:Hydrarthrosis / Q000209:etiology*; D007719:Knee Joint; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications / Q000601:surgery*; D017847:Patellar Ligament; D011183:Postoperative Complications; D012021:Reflex, Abnormal; D012189:Retrospective Studies; D013997:Time Factors