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Sunday, July 13, 2014

Is urinary incontinence the hidden secret complications after total hip arthroplasty? Baba T, Homma Y, Takazawa N, et al. Eur J Orthop Surg Traumatol. 2014; DOI 10.1007/s00590-014-1413-4.

MJ Strauhal, PT, DPT, BCB-PMD
July 9, 2014 Pelvic PT Distance Journal Club

Purpose of the study:  to investigate whether the posterior approach (PA) total hip arthroplasty (THA) differs from the anterior approach (AA) THA in influence on urinary incontinence (UI)
·         Study was done at the Department of Orthopedic Surgery, Juntendo University School of Medicine, Tokyo, Japan

Background: 
·         PA description
o   Patient position is lateral recumbent
o   Surgical method thought to be safer, provides wider visual field
o   Differences in muscle strength and walking ability compared to the AP were limited to the early post-op period; muscle strength at 6-12 months do not differ between PA and AP
o   Gluteus maximus is divided, short external rotators (ER) including the obturator internus are detached
o   T-shaped incision in the articular capsule, femoral head resected, prosthetic implanted
o   Short ER are sutured to their original position as much as possible

·         AA description
o   Intermuscular approach, also known as the Smith-Peterson approach; considered minimally invasive (MIS)
o   Muscle strength and walking ability recover earlier; dislocation rate is low
o   Patient position is supine
o   Fascia of the tensor fascia lata (TFL) is incised 2 cm lateral to the skin incision, preventing lateral femoral cutaneous nerve injury
o   Intermuscular space between the TFL and sartorius bluntly entered
o   Anterior articular capsule exposed, incised, resected to expose the femoral head
o   Implant size is confirmed by fluoroscopy

·         Hypothesis
o   PA dissection of the short ER, including OI which connects to the levator ani muscles, negatively affects symptoms of UI post-op THA
o   AA may improve ER contracture of the hip joint and leg length, increasing tension of the OI, which in turn would increase tension of the pelvic floor muscles (PFM) and improve UI post-op THA

Subjects:
·         76 Japanese females who underwent THA between 2011-2012
o   AA- 36 females
§  Mean age 64.2 + 12.5 years
§  Those with UI pre-op mean age 70.1 + 9.7 years
§  Those w/o UI pre-op mean age 62.5 + 10.1 years
§  Diagnoses: OA = 32, osteonecrosis of femoral head = 2, RA = 2
o   PA- 40 females
§  Mean age 64.2 + 9.4 years
§  Those with UI pre-op mean age 70.1 + 8.2 years
§  Those w/o UI pre-op mean age 62.8 + 12.8 years

Methods:
·         ICIQ-SF by way of direct interview before surgery and within 1-1.6 years post surgery
o   Five step evaluation of score change from pre to post-op
§  Decrease by 3+ points = improved
§  Decrease by 1-2 points = slightly improved
§  No change = unchanged
§  Increase by 1-2 points = slightly aggravated
§  Increase by 3+ points = aggravated

·         Statistics
o   Mann-Whitney U
o   T-test
o   P < 0.05 regarded as significant

Results:
·         Age was slightly higher in patients with pre-op UI in both groups, but not considered significant per t-test

·         AA group
o   UI improved post-op in 8, slightly improved in 1, remained unchanged in 26, slightly aggravated 1, aggravated in 0 (Table 1)
o   Of 13 patients with UI pre-op, it improved post-op in 9, remained unchanged in 4, aggravated in 0 (Table 2)
o   Of 23 patients w/o UI pre-op, it remained unchanged post-op in 22, slightly aggravated in 1 (Table 2)
o   In the 13 patients who reported UI pre-op (one patient could give more than one symptom)
§  SUI with cough/ sneeze = 9
§  SUI with exercise = 2
§  UUI before reaching toilet = 3
o   In the 9 patients in whom UI improved post-op but still had some symptoms
§  SUI with cough/ sneeze = 7

·         PA group
o   UI improved post-op in 1, remained unchanged in 30, slightly aggravated in 4, aggravated in 5 (Table 1)
o   Of 9 patients with UI pre-op, it improved in 1, remained unchanged in 3, aggravated in 5 (Table 2)
o   Of 31 patients w/o UI pre-op, it remained unchanged in 27, aggravated in 4 (Table 3)
o   In the 9 patients who reported pre-op UI
§  SUI with cough/ sneeze = 7
§  UUI before reaching toilet = 4
o   In 9 patients reporting UI aggravation post-op
§  SUI with cough/ sneeze = 9
·         UI improved with AA THA and aggravated with PA THA
o   Mann-Whitney U p = 0.0057

Conclusion:
·         As predicted, a significant difference was noted in post-op UI between the AA and PA
·         Authors assumed that surgery through AA improved ER of the hip joint and leg length leading to increased tension of the OI and hence the PFM which improved UI
o   Figure 2 axial view of CT scan of OI in patient undergoing AA showing maintenance of OI volume (a pre and b post-op)
·         PA approach dissects the OI and despite suturing, may not have been able to maintain normal strength leading to UI aggravation
o   Figure 2 axial view of CT scan of OI in patient undergoing PA showing atrophied OI (c pre and d post-op)
·         It is possible that conservation of the short ER promotes recovery of their strength and improves UI; this may be an advantage of the AA long-term in addition to short-term advantages for hip joint function

Limitations:
·         Retrospective self-evaluating survey with questionnaire only
·         No medium to long term comparison of AA with PA
o   Although they surveyed 40 PA patients an average of 5 years post-op (mean age 64.6) and 16 (40%) reported aggravation of UI, mostly SUI

Journal Club Discussion:
·         What other limitations do you identify with this study?
·         What are the clinical applications of this study?
·         How does this study compare to the one done at Funabashi Orthopedic Hospital?
·         What other questions/ hypotheses would you have liked to see the authors explore?

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