title: Is there any range-of-motion advantage to using bearings larger than 36mm in primary hip arthroplasty: A case-control study comparing 36-mm and large-diameter heads.
abstract: Large-diameter (>36mm) total hip arthroplasty (THA) has developed rapidly since the advent of ceramic-on-ceramic (CoC) bearings and highly cross-linked polyethylene. Theoretically, the increase in diameter reduces the risk of instability, although the advantage of calibers beyond 36mm has not been demonstrated in terms of range-of-motion recovery. We conducted a comparative study with a single prosthesis model to determine whether increasing the caliber beyond 36mm provides: (1) better recovery of range-of-motion, (2) a higher functional score, and (3) reduction of the dislocation rate.
  
  
  
  Increasing the range-of-motion by increasing the caliber beyond 36mm provides better range-of-motion.
  
  
  
  We analyzed two consecutive, single-operator cementless THA series performed via the mini posterior approach, which differed only in the bearing system (51 metal-on-metal [MoM] with a mean caliber of 45mm±3.3 [range, 40-54] and 61 CoC with a 36-mm caliber). Both series were comparable preoperatively in terms of age, diagnosis, functional scores, preoperative range-of-motion, body mass index, UCLA activity level, and Charnley score. We compared the joint range of movement at follow-up and the gains in range of movement, onset of dislocation, and functional scores (Oxford, Postel-Merle d'Aubigné [PMA]).
  
  
  
  The mean overall joint range-of-motion was 254°±39° (range, 150-310°) for an 81°±44° (range, -50 to 180°) gain in the MoM group and 256°±23° (range, 200-280°) for an 84°±40° (range, 0-160°) gain in the CoC group (NS). The MoM group presented the following results: Oxford=13.71±3.66 (range, 12-33) for a gain of 24.82 points±7.9 (range, -1 to 40), PMA=17.75±1.06 (range, 11-18) for a gain of 7.78 points±4.01 (range, 2-15). The CoC group had: Oxford=14.98±4.42 (range, 12-36) for a gain of 24.75 points±6.55 (range, 12-40), PMA 17.66±0.7 (range, 14-18) for a gain of 8 points±3.77 (range, 1-15). None of the gains and scores at follow-up differed significantly between the two groups. No episode of dislocation was identified.
  
  
  
  The current trend of increasing femoral head diameters beyond 36mm to improve the gains in joint range-of-motion and function is not warranted. The potential side effects of increasing the caliber call for even greater caution in the use of large-diameter heads because our hypothesis has not been confirmed.
  
  
  
  Case-control study, level III.
authors.affiliation: Université Lille, 59000 Lille, France; Service d'orthopédie, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France; Laboratoire d'anatomie et d'organogenèse, faculté de médecine, place de Verdun, 59045 Lille, France. Electronic address: delaycyril@gmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Delay
authors.affiliation: Université Lille, 59000 Lille, France; Service d'orthopédie, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Putman
authors.affiliation: Université Lille, 59000 Lille, France; Service d'orthopédie, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France; Laboratoire d'anatomie et d'organogenèse, faculté de médecine, place de Verdun, 59045 Lille, France.
authors.forename: G
authors.initials: G
authors.lastname: Dereudre
authors.affiliation: Université Lille, 59000 Lille, France; Service d'orthopédie, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France.
authors.forename: J
authors.initials: J
authors.lastname: Girard
authors.affiliation: Université Lille, 59000 Lille, France; Service d'orthopédie, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France.
authors.forename: V
authors.initials: V
authors.lastname: Lancelier-Bariatinsky
authors.affiliation: Unité de biostatistiques, université Lille, CHU de Lille, EA 2694 - santé publique : épidémiologie et qualité des soins, 59000 Lille, France.
authors.forename: E
authors.initials: E
authors.lastname: Drumez
authors.affiliation: Université Lille, 59000 Lille, France; Service d'orthopédie, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France.
authors.forename: H
authors.initials: H
authors.lastname: Migaud
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D016022:Case-Control Studies; D002516:Ceramics; D005260:Female; D005270:Femur Head; D006621:Hip Joint / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses; D008875:Middle Aged; D011474:Prosthesis Design; D016059:Range of Motion, Articular
keywords: Daily living activities; Hip prosthesis; Large-diameter head; Range-of-motion; Rehabilitation