Purpose: Infection after TJA is a rare but devastating complication. Horizontal laminar airflow has been advocated to reduce infection rate.

Methods: 896 consecutive primary and revision total joint arthroplasties of the hip and knee were retrospectively reviewed. The first 751 were performed before February 2004 in a horizontal laminar air flow room; the final 146 were performed without laminar flow from February 2004 through May 2005. All patients received the same perioperative antibiotics, wound management, and rehabilitation program. Body exhaust systems were worn in all cases.

Results: There were a total of 10 infections (1.1%) requiring surgical treatment, including 6 deep knee infections (0.67%), and four (0.45%) wounds (3 knees and 1 hip) with delayed healing or superficial infections. 9 of the infections occurred in the laminar flow group (1.2%), including all 6 deep knee infections (6/456=1.3%), 2 knee and 1 hip wound infection. Only 1 infection (0.68%), in a knee wound, occurred in the non-laminar flow group. There were no deep hip infections. Statistically, more knees became infected than hips overall (9/550=1.64% vs 1/346=0.29%)(p< 0.01) and more knees developed deep infection with laminar flow than without (6/456=1.2% vs 0/94=0.00%)(p< 0.1).

Conclusions: Laminar air flow did not alter the infection rate in THA, but may have increased infection rate in TKA. Infection is multifactorial, and longer follow up of the non-laminar flow group may reduce the differences seen. Nevertheless, this data agrees with other published data and is of significant concern for the TKA surgeon and patient alike.

Purpose: The effect of cemented total hip arthroplasty (THA) stem surface finish and geometry on clinical outcomes is controversial. This is the first report of results from a multi-center study evaluating a cemented, polished, triple-tapered prosthesis.

Methods: Two-hundred-seventeen C-Stems (DePuy, Warsaw, IN, USA) were implanted consecutively at three centers. Hips with 2-year minimum A-P radiographs receiving prospective clinical and independent retrospective radiographic examinations were included. Seven patients (9 hips) died and two had early revisions (one trauma-induced loosening; one due to poor cement technique). Of 206 hips remaining, 162 reached minimum follow-up. Cement-mantle grade, subsidence, stem-cement radiolucency, femoral osteolysis, and Harris Hip Score (HHS) were recorded annually.

Results: Mean age was 70 years (range 39–100). Of the 162 patients evaluated, 103 were female and 59 male. There were 17 deaths (20 hips) after minimum follow-up. Mean radiographic follow-up was 4 years (range: 2–6). At last follow-up, the mean HHS was 88 (range: 44–100). Cement-mantle grades were: A(27%), B(49%), C1(6%), C2(14%) and undetermined(4%). No stem subsidence greater than 2mm was observed. Debonding more than 1mm was noted in 6 hips (4%), including one cement fracture. Of 3 hips (2%) with femoral osteolysis, two instances were exclusively in proximal zones.

Conclusions: Excellent to good results were obtained in this multi-center, cemented, triple-tapered THA stem series. Radiographic results were similar to published results from other successful stems sharing these features. Further research is warranted to determine whether long-term results compare favorably to others designed to resist subsidence and loosening.

Purpose: Patellar Clunk is associated with posterior stabilized (PS) femoral components in which a scarred synovial suprapatellar nodule catches on the femoral box with active extension of the flexed knee. We investigated whether a rotating platform tibial component increases the incidence of patellar clunk.

Methods: From December 1998 to June 2006, a single surgeon performed 659 primary TKAs. 329 fixed-bearing tibial components and 330 rotating platforms were implanted. The same PS femoral component was used in all cases. All components were from the PFC Sigma Total Knee System (DePuy, Warsaw, IN, USA). The incidence of patellar clunk requiring reoperation was evaluated prospectively.

Results: There were 17 arthroscopies performed on 16 knees in 15 patients. One patient required bilateral arthroscopies, and one a repeat arthroscopy. 6 (1.8%) arthroscopies were required in the fixed bearing group, and 10 (3%) in the rotating platform group (p< 0.10 NS). The repeat arthroscopy was in the rotating platform group. Time to arthroscopy from the index surgery was 13.6 months (Range 5–40) for the entire group, 15.2 months (Range 8–40) for the fixed-bearing group, and 12.6 months (Range 5–20) for the rotating platform group (p< 0.10 NS).

Conclusions: The incidence of patellar clunk is not increased by the use of a rotating platform tibial component in TKA. While the mobile bearing may improve patellar tracking, causing the extensor mechanism to seat deeper in the trochlear groove, it does not seem to represent a risk factor for the development of the suprapatellar scarring that predisposes to patellar clunk.

Purpose: The original C-STEM (DePuy, Warsaw, IN, USA), a triple tapered polished collarless cemented stem, has an established clinical record. The new C-stem-AMT retains the identical intramedullary design, but enhances the extramedullary portion of the stem with a high offset option, and a mini-taper which is fully covered by the head, and accommodates a broad range of head diameters and neck lengths. This is an early report of clinical experience with the C-STEM AMT.

Methods: From March 2005 to June 2006, 34 C-STEMAMTs were implanted in 32 patients (21 females, 13 males) with mean age of 69 years (R 52–89). Diagnoses were Osteoarthritis in 30, AVN in 2, DDH in 1, and loose femoral implant in 1. Average follow-up was 9.7 months (R 3–18).

Preoperative and postoperative Harris Hip Scores, radiographs, and postoperative complications were recorded prospectively and compared to an early cohort of 66

C-Stems previously implanted between May 1999 and July 2001.

Results: Harris Hip Scores improved from 38 to 99 at one year. There has been no loosening, significant subsidence or reoperations. No dislocations have occurred, in contrast to 6 (9%) dislocations in the original C-Stem group.

Conclusions: As expected, the behaviour of the intramedullary portion of the C-Stem AMT is mirroring the experience with the C-Stem. The enhanced extramedullary design which accommodates additional neck lengths and head sizes, improves range of motion and provides additional offset has substantially reduced dislocation by facilitating accurate reconstruction of appropriate hip biomechanics.

Purpose: Double-tapered polished cemented femoral stems have demonstrated excellent long-term clinical results, but subsidence with cement mantle fracture, distal stress transfer and proximal stress shielding persist as problems. Adding a third taper from broad lateral to narrow medial purportedly reduces subsidence and improves proximal bone loading and preservation. We report our independent experience with a triple-tapered collarless polished cemented stem.

Methods: Between May 1999 and July 2001, 66 C-Stems (DePuy, Warsaw, IN, USA) were implanted in 45 females and 15 males, with a mean age of 67 years (R 35–86) and mean weight of 77 Kg (R 42–117). Diagnoses were OA in 62, RA in 1, AVN in 2 and fracture in 1. Average follow-up was 58 months (R 45–71).

Results: Harris hip scores improved from a mean of 43 (R17–100) to 84 (R 10–100). SF36 and WOMAC scores improved similarly. Six hips dislocated, but there were no reoperations. Subsidence was less than 1 mm in all cases. There was no radiographic stress shielding. Bone quality was maintained, especially in the critical medial calcar region, with positive bone remodeling along radial stress lines and improvement over time of some bone-cement interfaces.

Conclusions: The C-Stem, a triple-tapered collarless polished cemented stem, engages the surrounding cement mantle in an axially stable manner, minimizing subsidence to within the creep tolerances of cement. The radial stresses so generated favorably load the proximal bone, stimulating positive bone remodeling and eliminating stress-shielding. The clinical results at short to mid-term follow-up in this non-designer series are outstanding.

Purpose: Dislocation after THA is a multifactorial challenge involving patient, surgical and implant variables. The extramedullary features of a hip implant—offset, neck length, height, version, and head/neck ratio—significantly impact the stability of the reconstruction. We report a significant difference in dislocation rate between two different femoral stems.

Methods: Between May, 1998 and October, 2003, 263 primary THAs were performed by a single surgeon, utilizing identical surgical technique. Acetabular fixation was cementless with 3 varieties of cups in 262 hips and cemented in one hip. 141 hips had a single cemented femoral component (C-Stem, DePuy, Warsaw, Indiana), and 122 hips had a single cementless design (S-ROM, DePuy, Warsaw, Indiana).

Results: Diagnosis, gender, and side were similar between the groups. Mean age of the cemented group was 68.9 years(R 33 to 92) and of the cementless group was 51.9 years (R 19 to 79). The 3 acetabular designs were equally distributed between groups. All hips were implanted with 28 mm heads. There were 12/141 (8.5%) dislocations in the cemented group, and 3/122 (2.5%) dislocations in the cementless group (p < 0.10).

Conclusions: Stability after THA is affected by design features of a femoral implant, including height, neck length, offset, and version. The use of a single stem in all patients may not adequately address individual biomechanic variability. Careful preoperative templating, and the availability of multiple stem designs within a single fixation philosophy, may facilitate matching of extramedullary features to an individual patient’s anatomy in order to optimize postoperative hip stability.

Purpose: Mobile Bearing TKA has been reported to improve patellofemoral tracking due to the self-aligning impact of the mobile bearing. However, limited rotation of the mobile bearing may be insufficient to impact patellar tracking in an otherwise well-balanced TKA.

Methods: Between December 1998 and October, 2003, 445 primary TKAs were performed via transpatellar arthrotomy. The same posterior stabilized femoral component was implanted in all knees. There were 312 fixed bearings and 133 rotating platforms implanted. In order to optimize patellar tracking, a neutral mechanical axis was established, femoral components were lateralized and externally rotated, patellar buttons were medialized, tibial components were externally rotated, and gaps and ligaments were meticulously balanced. Lateral release was performed based on intraoperative assessment of patellar tracking.

Results: Lateral releases were performed in 47 of 312 (15%) fixed bearing knees, and in 14 of 133 (11%) mobile bearing knees (p=NS). Average preoperative alignment in the fixed bearing knees was –5 degrees (R-7 to 20), and in the mobile bearing knees was 0 degrees (R-10 to 20).

Conclusions: Careful surgical technique with attention to the details of optimizing patellar tracking may be the most important factor determining the rate of lateral release. The self-aligning ability of mobile bearing TKA, which has been postulated to improve patellar tracking, may not reduce the need for lateral release in the cohort of patients in whom lateral tilt and subluxation of the patella persist even after other factors affecting patellar tracking have been surgically addressed.

Purpose: Mobile bearing total knee arthroplasty (MBTKA) has been complicated by bearing spinout and dislocation. Balancing the flexion and extension gaps is a basic principle of knee reconstruction, but is often achieved in a haphazard manner. This balance is critical to prevent bearing spinout and dislocation. A surgical technique is presented which actively balances flexion and extension gaps, and avoids spinout and dislocation in MBTKA.

Methods: Between February, 2002 and May, 2004 , 180 primary MBTKAs were performed, utilizing the PFC ∑RP (DePuy, Warsaw, Indiana, USA) system with a PS femoral component. The surgical technique consisted of distal femur and proximal tibia resection, followed by ligament balancing and measurement of the extension gap utilizing laminar spreaders. With laminar spreaders placed in the knee at 90 degrees of flexion, an AP cutting block with free rotation and AP translation, attached to an intramedullary rod was positioned on the distal femur in order to create a symmetric flexion gap matching the thickness of the previously established extension gap. After AP resections, gap balance was verified using spacer blocks. Preparation of the bony surfaces to accept the prostheses was completed in a standard fashion.

Results: No bearing spinout or dislocation, or instability has occurred.

Conclusions: Meticulous surgical technique directed toward strict balance of the flexion and extension gaps prevents bearing spinout and dislocation in MBTKA, and is critical to the success of this technology which offers the potential long-term benefits of lower wear, soft tissue load sharing and improved overall knee mechanics.

While cemented THA has been considered the gold-standard, cementless THA has become a common and even preferred approach for younger individuals and those with acceptable bone stock. Which technology provides superior results and in which patients, however, remains controversial, and has not been systematically studied.

The literature suggests that well-fixed cementless prostheses, and even composite beam cemented prostheses cause stress shielding and progressive osteopenia in the surrounding bone. This compromises and complicates subsequent surgery, particularly in young patients who are at risk for multiple revisions, and may increase the risk of periprosthetic fracture, component failure, and aseptic loosening.

In contrast, polished tapered stems, by behaving according to a taper-slip philosophy, favorably load bone, converting shear stress into radially directed hoop stresses, through the medium of the surrounding visco-elastic cement and its resulting ability to creep.

The C-Stem, (DePuy, Warsaw, Indiana, USA) a cemented triple tapered polished stem is the only stem with published data demonstrating positive remodeling of bone in as many as 20% of patients, and preservation of the critical proximal medial calcar bone. Additional anectdotal reports confirm these results.

The long-term results of cemented stems, which necessarily involve the surviving youngerst cohort in any series, are outstanding. The tapered polished stem technology may improve these historical results, and, by limiting periprosthetic stress shielding and osteopenia, may revolutionize the application of cemented THA in younger patients for whom preservation of bone stock through favorable bone loading is so critical to sustained success of the primary and subsequent revision surgeries.