Purpose: Even with modern ancillary and good surgical experience, rotational implant positioning is sometimes sub-optimal, leading to poor results. Except for obvious cases with patellar instability, the symptoms are often vague and non-contributive to the diagnosis of failure. This is why implant malpositioning and particularly malrotational postioning remain an underestimated cause of failure after primary total knee arthroplasty (TKA). We report our experience with TKA revision for rotational malpositioning.

Method: We retrospectively assessed the results of TKA revisions in 22 knees for malrotational positioning. In all cases, malrotational implant positioning was confirmed by CT-scan according to Berger’s protocol.

Results: Mean age was 66 years (47–74) at the time of the primary TKA. After the index procedure, all patients presented early anterior knee pain with patellar instability (tilt and subluxation in ten cases, and permanent patellar dislocation in two cases). Malrotational positioning predominated on the tibial component with mean 23° internal rotation. Mean cumulative malrotation (tibial plus femur) was 22° internal rotation. All but four patients underwent femoral and tibial component revision. In two cases, only the tibial component was revised, and in two other cases, isolated transposition of the anterior tibial tuberosity was carried out. One was a failure, and finally underwent a successful full revision. At a mean follow-up of 30 months (12–60), we noted significant functional outcome improvement. One patient, who underwent a patellectomy previously at the index TKA procedure, had persistant anterior knee pain. No patient presented patellar instability.

Conclusion: The diagnosis of implant malrotational positioning is sometimes difficult. The most common errors are tibial component positioning. In case of suspicion of malrotational positioning, protocolized CT-scan allows quick and simple diagnosis. If the malrotation is confirmed, TKA revision should be performed upon patient disability and severity of the symptoms. It is important not to delay the surgery, particularly in cases of patellofemoral dislocation because of the risks of developing soft tissue contractures resulting in a more difficult revision procedure.

Purpose: Femoral neck narrowing (FNN) has been reported after metal-on-metal hip resurfacing (HR). It is significant (> 10%) in a number of cases (from 0 up to 27.6%). Its origin remains unclear, but bone remodelling, impingement, head necrosis and osteolysis have been incriminated. The aims of this study were to assess these issues and describe their consequences in a prospective series with a minimum follow-up of five years.

Method: Fifty-seven HRs in 53 patients (30 men, 23 women, average age 49.2±8.4 years) were included prospectively with clinical (WOMAC, UCLA activity score) and radiological evaluation at one, two and five years. All patients received the Durom™ resurfacing system (Zimmer, Warsaw, IN, USA), with cementless acetabular cup and cemented femoral implant. All cases were undertaken via a posterior approach. Femoral and acetabular implant positioning was assessed. The neck-to-head prosthesis (N/H) ratio was calculated at the junction of the neck with the femoral component and at mid-distance between the neck junction and the inter-trochanteric line (N1/2/H) on anterior-posterior view. Ion concentrations (chromium, cobalt and titanium) were measured at 12 months. We considered p< 0.05 as the significance level.

Results: The N/H ratio decreased significantly at one, two and five years in comparison to the postoperative data (p< 0.01 for all parameters) and N1/2/H declined significantly only at one and two years (p=0.003 and p=0.03, respectively). There was no difference in the N/H ratio or N1/2/H between two and five years. We encountered no deleterious consequences of FNN on clinical outcome, and no significant relationship with cup positioning, gender, body mass index or level of activity. Femoral positioning in valgus was associated with a decrease in N1/2/H at one and two years (p=0.02), whereas the N/ H ratio tended to be lower when cobalt concentration was elevated (p=0.08). Significant FNN was observed in two cases at two years (−12.9% and – 11.1%) with a localized and progressive femoral anterior-superior notch absent on immediate postoperative X-rays. At five years, we noted three other cases with circumferential FNN, limited at the junction neck-cup area (average narrowing around – 20% between two and five years). One of these cases presented a femoral stem fracture. Osteonecrosis was confirmed during surgical revision.

Conclusion: In the current group, FNN was seen infrequently up to five years after surgery (9%). Mechanically-induced remodelling should be differentiated from overall FNN which may be due to femoral head necrosis. In this case, revision could be proposed before implant failure or femoral loosening. Impingement causes very early and localized FNN at the upper part of the neck; for these patients, simple observation should be the rule, all the more since they are usually pain-free and rarely disabled.

Purpose: Tribological studies of hip arthroplasty suggest that larger diameter metal-on-metal (MOM) articulations would produce less wear than smaller diameter articulations. Other advantages of these large femoral head implants include better stability with lower dislocation rates and improved range of motion. The aim of the present study was to compare chromium (Cr), cobalt (Co) and titanium (Ti) ion concentrations up to one year after different large diameter MOM total hip arthroplasties (THAs).

Method: One hundred and twelve patients were randomized to receive large (femoral head > 36 mm diameter) metal-on-metal articulation THA (LDH) from one of the following companies: Zimmer, Smith & Nephew, Biomet or Depuy. Samples of whole blood were collected pre-operatively and post-operatively at six months and one year. Cr, Co and Ti concentrations were measured by high-resolution mass spectrometry in an independent laboratory. All LDH implants have a modular Cr-Co tapered sleeve for leg length adjustment, except for Biomet with its sleeve made of Ti. All groups had Ti stems, and Zimmer and Biomet had, in addition, a Ti acetabular porous surface for secondary fixation. We undertook statistical analysis (SPSS 14.0) with p< 0.05 as significant.

Results: The groups were comparable in respect to pre-operative parameters (age, gender ratio, body mass index, etc.) as well as post-operative functional scores at six months and one year. We found that Biomet, Depuy and Smith & Nephew LDH had similar Co ion levels at 12 months post-op with 1.5, 1.4 and 1.6 ug/L, respectively. Durom LDH had the highest Co level with 2.3 ug/L (p< 0.01 versus the three other groups). The highest Ti ion levels were observed in the Zimmer group with 3.2 ug/L (p< 0.01 versus the three other groups) and the Biomet group with 2.0 ug/L (p=0.01 versus Zimmer and NS versus the other 2). Ti levels tripled versus pre-op for BHR and ASR (0.5 versus 1.5 and 0.5 versus 1.4 ug/L).

Conclusion: Different implant factors may influence metal ion levels measured in whole blood: articular surface wear and implant passive corrosion. Zimmer’s Durom LDH presents higher Co levels than the other groups. Since previously-published Durom hip resurfacing (same bearing characteristics as Durom LDH) showed much lower Co ion results, the modular sleeve may be incriminated. The plasma-sprayed acetabular surface of Zimmer’s and Biomet’s components seems to be responsible for the significant difference in Ti versus the other implants. Biomet’s plasma-sprayed Ti appears to be less prone to corrosion than Durom’s plasma spray coating. When evaluating metal ion release from MOM THA, total metal load from the implants should be considered, and newer implant designs should be evaluated scientifically before their widespread clinical use. LDH-THA should be seen as an improvement and should not be blamed as the source of metal ion release when a specific implant produces unsatisfactory results.

Background: Acetabular implant revision with large bone defects, can be challenging. One of the reconstruction options is a “jumbo cup” (outer diameter ≥62mm in women and ≥66mm in men). We hypothesized that cementless jumbo cups is a reliable technique to reconstruct hip joint with satisfying radiological and clinical outcomes.

Material and Methods: Fifty-two consecutive acetabular revisions arthroplasty where a cementless jumbo cup was used were assessed. Clinical outcomes were assessed by Harris Hip Score (HHS), WOMAC index and SF-12. Hip centre was assessed on anteroposterior (AP) view according to Pierchon’s criteria. The reconstructed hip center was considered as satisfying when its location was located from −10 to + 10 mm proximally (y axis) and/or medially (x axis) in comparison with ideal theoretical hip center location. Cup migration and modification of abduction angle were considered as significant when there were respectively ≥5mm and to ≥5° in comparison with the immediate postoperative AP view.

Results: Mean component size was 67.6 mm (min 62, max 81). According to Paprosky classification, there were 5 cases of type 1, 11 type 2A, 12 type 2B, 11 type 2C, 11 type 3A and 2 type 3B. Cancelous bone chips allograft were used in 34 cases and bulk bone allograft in 14. Immediate postoperative AP view showed a mean abduction cup angle of 41.3° (26–53), a satisfying hip centre positioning in 78% on x axis and in 70 % on y axis. In the remaining cases, we noted an improved implant positioning. For the patients with intact contra-lateral hip (n=29), we noted, in comparison with normal side, a mean lateralisation of the hip center of 3 mm (−10 – +16) and a mean ascension of 7 mm (−10 – +33) associated with an average limb length discrepancy of – 4 mm (−19 – +9). At the last follow up [radiological data: 79 months (24–236) and clinical data: 88 months (27–241)], 6 patients were died and 3 were lost of follow up. The mean HHS was 82% (15–100), WOMAC 86% (27–100), SF-12 46 (14–61) and 53 (15–63). Bone graft integration was completed in all but 3 cases. Significant cup migration (≥5mm) occurred in only one case. The complications were: dislocation in 5 cases (4 revisions with constrained liner), infection in 4 cases (2 treated conservatively and 2 revised in 2 times procedure) and Brooker’s type III or IV ectopic ossifications in 11 cases. No case required revision for aseptic loosening.

Discussion: Jumbo cups appear as a reliable procedure to manage bone loss in acetabular revision. The complication rate is comparable with other reconstruction procedures (massive allograft, reinforcement rings, high hip center…). Cementless fixation and satisfying hip center restoration promote respectively the bone integration and allow an optimal biomechanical joint functioning. These are the main conditions for high long term survival rate.

The two-incision technique uses strategically located incisions to insert the prosthesis components in to specific intermuscular or internervous planes in an effort to minimize damage to these tissues. Even though there are many reports about safety and benefits of bilateral simultaneous total hip arthroplasty (THA), none of them has reported about either one-incision or two-incision bilateral simultaneous minimally invasive (MI) THA. This study aimed to assess the feasibility of bilateral simultaneous MI two-incision THA in terms of clinical, radiological and functional outcomes.

Sixty two patients, in the age of 24 to 69 years were operated for bilateral simultaneous THA using modified two-incision technique and followed for average 41 months. In the technique of two-incision THA described by Mears, they used modification of Smith Peterson approach for insertion of acetabular component and femoral component is inserted through a small incision situated between greater trochanter and iliac crest, centered directly in line with the femoral shaft. We modified this technique and used part of Watson Jones approach for insertion of acetabular component with patient in lateral position. The posterior incision for insertion of femoral component is through intermuscular interval between gluteus medius and piriformis.

The average Harris Hip score improved from 41.8 (range 10 to 59) preoperatively to 95.3 (range 73 to 100) postoperatively (P < 0.05). WOMAC score improved from median of 66.2 (range 31 to 96) preoperatively to 5.0 (range 0 to 19) postoperatively (P < 0.05). Forty-nine (79.03%) patients were pain-free at the time of first follow up (6 weeks after surgery) and remained pain-free till the last follow up, while remaining 13 (20.97%) had only slight pain. Out of those 13, 3 patients complained of occasional mild pain at last follow up. Fifty (80.64%) patients were walking without limp, while remaining 12 (19.35%) had only slight limp at 6 months. Out of those 12, 2 patients had persistent limp at final follow up. Fifty-eight (93.53%) patients were walking without support, 56 (90.32%) were able to walk unlimited distance and 55 (88.70%) were able to climb stairs without using a railing. Walking with walker was started on average 3.7 days (range 1 to14 days) and walking with crutches was started on average 10.3 days (range 1 to 49 days) postoperatively. Patients were able to walk without support on an average 48 days (range 14 to 120 days) and use stairs without support and without any discomfort on an average of 50 days (range 5 to 150 days). The average lateral opening angle of acetabulum was 40 ° and anteversion was 12 °. All femoral components were implanted in neutral to 5 ° valgus position. None of the femoral component showed subsidence of more than 3 mm. The filling of the femoral canal by the prosthesis was excellent in all cases. Post-operative periprosthetic fracture occurred in 2 patients and delayed infection occurred in 1 patient.

In conclusion, bilateral simultaneous two-incision minimally invasive THA gives satisfactory clinical and radiological results in comparison with conventional THA. It is safe in experienced hands, without any additional risk of complications. It provides excellent functional outcome and patient satisfaction.