Hospital for Special Surgery, Stavros Niarchos Foundation Complex Joint Reconstruction Center, 535 East 70th Street, New York, NY, 10021, USA.
Department of Orthopedics (Friedrichsheim), University Hospital Frankfurt, Goethe University, Frankfurt, Main, Germany.
Arch Orthop Trauma Surg. 2024 Apr;144(4):1703-1712. doi: 10.1007/s00402-024-05234-4. Epub 2024 Mar 15.
There are two variants regarding the low location of the patella in relation to the tibio-femoral joint line: patella baja (PB) and pseudo-patella baja (PPB). The purpose of this study is to investigate the incidence of PB and PPB in a cohort of patients that underwent revision total knee arthroplasty (rTKA) for aseptic reasons and describe any differences in each group's ROM.
This retrospective study included 114 patients that underwent aseptic revision TKA surgery between 2017 and 2022. Patients were revised either for stiffness (Group 1) or aseptic loosening/instability (Group 2). The Insall-Salvati ratio (ISR) and Blackburne-Peel ratio (BPR) were used to evaluate the patellar position. ISR < 0.8 defined PB, while cases with ISR ≥ 0.8 and BPI < 0.54 were defined as PPB. ROM was measured and a subanalysis was conducted to investigate the progression of the values of ISR and BPR.
55 patients comprised Group 1, and 59 patients comprised Group 2. Overall, 13 cases (11.4%) had PB before rTKA and 24 (21%) had PB after rTKA. Cases with PPB were 13 (11.4%) before and 34 (29.9%) after rTKA. Group 1 patients presented with more PB before and after rTKA (12.8% vs 10.2% and 27.3% vs 15.2% respectively). However, after rTKA Group 1 patients presented with less PPB (20%) compared to Group 2 (39%) (p = 0.02). In Group 1, patients with PPB after rTKA had less ROM compared to those without PPB [83.2 (± 21.9) vs 102.1 (± 19.9) (p = 0.025)]. The subanalysis (69 patients) showed a statistically significant decrease in ISR before and after rTKA (p = 0.041), and from the native knee to post-rTKA (p = 0.001). There was a statistically significant decrease in BPR before and after rTKA (p = 0.001) and from the native knee to both pre- and post-rTKA (p < 001).
After undergoing rTKA, the incidences of both patella baja (PB) and pseudo-patella baja (PPB) increased. Stiffness in the knee was associated with a higher incidence of PB, while non-stiffness cases showed a significantly higher incidence of PPB. Patients with stiff knees and PPB after rTKA experienced a significant reduction in range of motion (ROM). Additionally, the study revealed a noteworthy decrease in ISR and BPR with each subsequent surgery. This information is crucial for healthcare providers, as it sheds light on potential risks and outcomes of rTKA, allowing for improved patient management and surgical decision-making.
III.
髌骨相对于胫股关节线的低位有两种变异：髌骨低位（PB）和假性髌骨低位（PPB）。本研究的目的是调查一组因无菌原因接受翻修全膝关节置换术（rTKA）的患者中 PB 和 PPB 的发生率，并描述每组 ROM 中的任何差异。
本回顾性研究纳入了 2017 年至 2022 年间因无菌原因接受翻修 TKA 手术的 114 例患者。患者因僵硬（第 1 组）或无菌性松动/不稳定（第 2 组）而接受翻修。Insall-Salvati 比（ISR）和 Blackburne-Peel 比（BPR）用于评估髌骨位置。ISR<0.8 定义为 PB，而 ISR≥0.8 且 BPI<0.54 的病例定义为 PPB。测量 ROM，并进行亚分析以调查 ISR 和 BPR 值的变化。
第 1 组有 55 例患者，第 2 组有 59 例患者。总体而言，13 例（11.4%）在 rTKA 前有 PB，24 例（21%）在 rTKA 后有 PB。PPB 病例分别为 13 例（11.4%）和 34 例（29.9%）。第 1 组患者在 rTKA 前后均出现更多的 PB（分别为 12.8%比 10.2%和 27.3%比 15.2%）。然而，rTKA 后第 1 组患者的 PPB 较少（20%比 2 组 39%）（p=0.02）。在第 1 组中，rTKA 后出现 PPB 的患者的 ROM 明显低于未出现 PPB 的患者[83.2（±21.9）比 102.1（±19.9）（p=0.025）]。亚分析（69 例）显示 rTKA 前后 ISR 有统计学显著下降（p=0.041），以及从原膝关节到 rTKA 后（p=0.001）。rTKA 前后 BPR 有统计学显著下降（p=0.001），以及从原膝关节到 rTKA 前后（p<001）。
接受 rTKA 后，髌骨低位（PB）和假性髌骨低位（PPB）的发生率均增加。膝关节僵硬与 PB 发生率较高相关，而非僵硬病例则与 PPB 发生率显著较高相关。rTKA 后膝关节僵硬伴 PPB 的患者 ROM 显著减少。此外，研究还发现 ISR 和 BPR 随每次后续手术显著下降。这些信息对医疗保健提供者至关重要，因为它揭示了 rTKA 的潜在风险和结果，从而改善了患者管理和手术决策。
III 级。
