A comprehensive analysis on contributing factors for varus or valgus malposition of femoral stems in uncemented total hip arthroplasty via DAA.

Background: Varus or valgus malposition of uncemented femoral stems have been described to have detrimental effects for long term implant survival. Various pre- and intra-OP factors have been suggested to be relevant, one of them being the approach to the hip. The aim was to investigate several pre- and intra-OP factors associated with femoral stem malpositioning in a large series of DAA hips. Methods: A series of 400 consecutive patients (416 hips) who underwent navigated (Brainlab) cementless Total Hip Arthroplasty (THA) in 2022 (Corail or Actis stem DePuy Synthes) via a direct anterior approach (DAA) was analyzed. Preoperative data were collected based on patients' demographics, radiographic information [critical trochanteric angle (CTA), centrum collum diaphyseal (CCD) angle, greater trochanter overhang, femoral neck resection angle, femoral neck resection height and Door classification], and these were correlated with the postoperative stem position. Univariable and multivariable linear regression were carried out to determine significant factors that contribute to varus and valgus stem malalignment. Results: With the DAA approach, 56.5 % of stems were placed in an optimal neutral position, 38.4 % were in acceptable position of 0.1°-2° varus/valgus and only 5 % had a deviation larger than 2° varus/valgus. The critical trochanteric angle (CTA) was statistically significant in determining varus stem placement whereas centrum collum diaphyseal angle (CCD) was found to affect valgus stem malpositioning. All other factors have shown no relevant effect on stem placement using stepwise regression method. Conclusion: In DAA, 95 % of stems were found in a varus/valgus position of 2° or less. In pre-operative measurement, only femoral morphology (e.g. CTA & CCD) were found to be relevant, affecting varus/valgus stem malposition. All other tested modifiable and non-modifiable factors had no significant effect. Therefore, pre-OP templating including measurement of CTA and CCD, intra-operative assessment as well as proper operative techniques are paramount to prevent excessive varus/valgus mal-position of femoral stem in DAA.

Outcomes of Impaction Bone Grafting in the Management of Acetabular Defects with the Use of Uncemented Acetabular Cups: Do Autografts and Irradiated Femoral Head Allografts Integrate?

Introduction: Acetabular impaction bone grafting (AIBG) has been used widely to reconstruct acetabular defects in complex primary and revision cases. The aim of this study was to look at the outcomes AIBG using either frozen irradiated femoral head allografts or autografts with uncemented acetabular cups. Method: We retrospectively reviewed 38 patients who had AIBG and uncemented cup reconstruction of the acetabulum performed between 2008 and 2021 for complex primary and revision surgery. Graft incorporation, radiological loosening and cup migration were evaluated in follow-up X-rays. Result: There were 24 complex primary and 14 revision total hip arthroplasty. Autografts were used in 10 hips with smaller defects, while 28 hips with larger defects required frozen irradiated femoral head allografts. Using Paprosky classification to evaluate acetabular defects; 8 patients were classified as 2A, 12 as 2B, 7 as 2C, 8 as 3A and 3 as 3B. The Kaplan-Meier survival rate for AIBG with uncemented cups in our series is 89.70% in 10 years. Acetabular cup position was anatomically restored in all autograft AIBG cases and in 25 out of 28 in the allograft group. The mean pre-operative Oxford Hip Score (OHS) was 19 (range 10-24) and post-operative OHS was 39 (range 21-48) (p < 0.001). Conclusions: The mid- to long-term results for AIBG and uncemented acetabular cups is good. With newer and more porous uncemented cups especially revision cups, it may serve as an extended indication to achieve solid fixation together with AIBG technique in managing acetabular defects of ≤ 3A.

A Rare Presentation of Patella Button Aseptic Loosening After a Total Knee Replacement Without Evidence of Radiographic Loosening.

Patella resurfacing in total knee replacement (TKR) has been shown to reduce the rate of anterior knee pain, but there are complications from patella resurfacing. A 54-year-old male underwent a left primary TKR with patella resurfacing 15 years ago. He developed spontaneous progressive anterior knee pain for six months. At revision surgery, his patella button was found to be loose. Loosening of a three-peg patella button is rare. A high index of suspicion of patella button loosening should be suspected in patients who present with anterior knee pain after patella resurfacing.