Bauer Stefan, Blakeney William G, Lannes Xavier, Wang Allan W, Shao Wei
Centre de l'épaule et du membre supérieur de la Côte, Ensemble Hospitalier de la Côte, Morges, Switzerland.
School of Surgery, University of Western Australia, Perth, WA, Australia.
JSES Int. 2024 Jun 19;8(5):1087-1094. doi: 10.1016/j.jseint.2024.06.003. eCollection 2024 Sep.
There has been a trend to shift from a 155° and 145° neck-shaft-angle (NSA) to a more "anatomical" reverse shoulder arthroplasty with less distalization and a 135° NSA. Multiple studies have shown that a 135° NSA is beneficial for motion. There are some concerns about primary implant stability with a 135° NSA. When instability is detected, increasing the tension with thicker inlays or changing the NSA to 145° are possible solutions. A retentive 135° (Ret135) inlay may be an alternative to avoiding increased distalization; however, retentive liners are widely regarded as salvage options reducing range of motion (ROM) and avoided by most surgeons. The hypothesis of this study was that a retentive 135° insert of the tested implant system may not have drawbacks for impingement-free ROM compared to a standard 145° insert (Sta145).
In this computer model study, 22 computed tomographic scans (11 males/11 females) were used to create models with a constant humeral stem (Perform/Stryker) and +3 mm lateralized baseplate +36 mm glenosphere for females and +6 mm lateralized baseplate +39 mm glenosphere for males using Blueprint software (Imascap, Brest, France). A Ret135, standard 135° (Sta135), and Sta145 (+10°) insert were compared for adduction (ADD), extension (EXT), external rotation (ER), and internal rotation (IR) all with the arm at the side as well as for combined IR (CIR = EXT + IR) and combined notching relevant (CNR) ROM (EXT + ER + IR + ADD).
Sta135 showed significantly better ROM for ER, IR, ADD, EXT, CNR ROM, and CIR compared to Ret135 ( < .05) and significantly better EXT and ADD compared to Sta145 ( < .0001). Comparison of Ret135 and Sta145 showed equivalent ROM performance, which was slightly better but nonsignificant for ADD ( = .16), EXT ( = .31), CNR ROM ( = .7), and CIR ( = .54) in favor of Ret135. Isolated IR ( = .39) and ER ( = .32) were slightly better but nonsignificant in favor of a Sta145.
For this implant system tested in a computer model, a 135° standard liner offers the best ROM. A 135° retentive liner maintains at least equivalent CIR and motion to prevent notching compared to a standard 145° liner. 135° retentive liners are more than salvage options and may help to prevent distalization and overtensioning by increased liner thickness.
目前存在一种趋势，即从155°和145°的颈干角（NSA）转变为更“解剖学”的反向肩关节置换术，减少远移并采用135°的NSA。多项研究表明，135°的NSA对活动有益。对于135°的NSA，人们对初次植入物的稳定性存在一些担忧。当检测到不稳定时，增加较厚衬垫的张力或将NSA改为145°是可能的解决方案。一种具有固定作用的135°（Ret135）衬垫可能是避免增加远移的一种选择；然而，具有固定作用的衬垫被广泛认为是会减少活动范围（ROM）的补救选择，大多数外科医生会避免使用。本研究的假设是，与标准的145°衬垫（Sta145）相比，所测试的植入系统的具有固定作用的135°衬垫在无撞击ROM方面可能没有缺点。
在这项计算机模型研究中，使用22例计算机断层扫描（11例男性/11例女性），通过Blueprint软件（法国布雷斯特的Imascap）创建模型，女性使用恒定的肱骨干（Perform/Stryker）、+3 mm外移的基板和+36 mm的球窝，男性使用+6 mm外移的基板和+39 mm的球窝。比较Ret135、标准135°（Sta135）和Sta145（+10°）衬垫在手臂位于身体一侧时的内收（ADD）、伸展（EXT）、外旋（ER）和内旋（IR）情况，以及联合内旋（CIR = EXT + IR）和联合切口相关（CNR）ROM（EXT + ER + IR + ADD）。
与Ret135相比，Sta135在ER、IR、ADD、EXT、CNR ROM和CIR方面显示出明显更好的ROM（P <.05），与Sta145相比，EXT和ADD明显更好（P <.0001）。Ret135和Sta145的比较显示ROM性能相当，在ADD（P =.16）、EXT（P =.31）、CNR ROM（P =.7）和CIR（P =.54）方面Ret135略好但无统计学意义。孤立的IR（P =.39）和ER（P =.32）略好但无统计学意义，有利于Sta145。
对于在计算机模型中测试的这种植入系统，135°的标准衬垫提供了最佳的ROM。与标准的
