Scientific Publications

Gaillard-Campbell D, Gross T. Preventing Early Femoral Failures in Hip Resurfacing: Outcomes of a risk-startification Protocol in 5117 cases. submitted Hip International. 2026.

This paper describes our long-term program of fracture prevention and references several previous papers. Femoral neck stress fractures occur in the initial 6 months postoperatively. Head collapse is seen between 6 month and 2 years. We believe that these are biological failures of the bone and are grouped together as Early Femoral Failures (EFF). Initially we identified the high risk groups of low bone density and BMI over 29 and determined their risk. Then we demonstartated fractures could be prevented in one of the highest risk groups using a combination of a "slow" recoverey program in combination with alendronate. In this study We confirmed the previous protocol and extended protection for the intermediate group that had a T score of the operative femoral neck between 0 and -1.5. Their untreated risk of 2.1 was reduced to 0.2%. Unfortunately the other intermediate group with a BMI>29 experienced no statistical improvement. Their overall risk is approximately 0.5%. I practice minimal patient selection. I perform the operation in patients with osteoporosis and with a BMI up to 35. The overall group of unselected patients saw a reduction in EFF from 1.5% to 0.2 % using our bone management protocol.

Gross TP, Gaillard-Campbell MD. Outcomes of metal-on-metal hip resurfacing arthroplasty: a single-surgeon series of 6114 cases with 2-19 year follow-up. J Orthop Surg Res. 2025;20(1):974.

This summarizes my work with the Biomet Recap/Magnum hybrid implant from 2005 to 2007 and the uncemented version from 2007 to 2022. KM implant survivorship was 97.5% at 19 years for the combined cohort. It was KM 98.2% 16-year for the UC group and KM 94.6% 19-year for the hybrid group. There was no difference in outcome based on age, Dx or implant size since 2007, and no difference based on sex since 2012. Minimal patient selection is practiced. 4% of patients had residual moderate or greater pain, 3% were not satisfied, We have seen no AWRF since 2009 and no postoperative infections since 2007. Extensive detail on failures, reoperations and other complications are provided. Ion levels are reported in 66% of cases.

Gaillard-Campbell D, Gross T. Degenerative gluteal tears associated with hip arthroplasty. BMC Musculoskelet Disord. 2025;26(1):56.

Degenerative tears of the abductor system are seen in patients undergoing HRA from the posterior approach in 1% of men and 3.6% of women.Women over 60 had an incidence of 5%. These tears are easily missed and MRI are not completely reliable. Any thick bursa should be resected, because these are associated with tears. If the medius is intact and a gritty, pebbly trochanter is palpated, take down the anterior third of the medius and look at the minimus. All tears were repaired. All patients were maintained on an extra slow program of progressive weight beaing that lasted 4.5 months. Outcomes were usually excellent. The mean HHS was 3.2 point less than the control group. At 2 years 70% had no limp and 21% had a slight limp.

Gaillard-Campbell D, Gross T. Uncemented hip resurfacing in patients over 65: 16-year outcomes from a large, single-surgeon series. Musculoskelet Surg. 2025.

The KM 98.2% 16-year implant survivorship in 395 patients over 65 was the same as for the entire younger HRA cohort. The early femoral failure rate was only 0.3%. Women had the same outcome as men. Durability far surpasses 95% 10-year and 91% 15 year KM survivorship of THR in registries.

Gaillard-Campbell D, Gross T. Magnum metal-on-metal uncemented total hip replacement: 8- to 18-year outcomes of 211 cases. Musculoskelet Surg. 2024;108(4):449-57.

The 18-year KM survivorship in 211 cases with mean age 59 using the uncemented Biomet  Magnum MoM THR was 97.4%. There were no dislocations. There was one AWRF, 3 trunion failures, and one late infection. This far surpasses registry benchmarks. This implant had a unique large titanium neck adapter that placed the mixed metal junction in a low torque position and had a ti-Ti junction at the high torque connection.

Jones CS, Gaillard-Campbell D, Gross TP. Long-term clinical outcomes of the Biomet M2a-38: a retrospective review of 335 total hip arthroplasty cases. J Orthop Surg Res. 2023;18(1):721.

The 20-year KM survivorship was 97.6% in 335 cases with mean age 64 using the uncemented Biomet M2a38 MoM THR system. The acetabular component had a near hemispherical coverage arc resulting in no cases of AWRF. This bearing was 38mm in size. Th mixed metal junction was subjected to moderate torque and we saw 4 late trunion corrosion cases (1.2%). There was one revision due to recurrent instability. Results far surpasse dregistry benchmarks.

Gaillard-Campbell DM, Gross TP. Hypersensitivity to metals in metal-on-metal hip arthroplasty: a prospective study of one hundred and thirty five lymphocyte transformation tests. Int Orthop. 2023.

LTT do not predict failures or unexplained pain in MoM HRA. 34% 0f patients tested positive to one of the metals in the implant.The rate was the same for men and women. None of these had a failure of any sort. All three case with residual unexplained pain had a negative LTT. 38.5% tested positive to Nickel, 19.3% to Titanium, 0.7% to cobalt. Internal allergies to metals remains a speculative concept at best.

Gaillard-Campbell MD, Fowble C, Webb L, Gross TP. Hip resurfacing as an outpatient procedure: a comparison of overall cost and review of safety. Musculoskelet Surg. 2021;105(1):111-6.

We reported on the first 485 out patient HRA done at our ASC.In 39 patients who had a previous HRA at the hospital 95% preferred the ASC experience. Mean cost was $26, compared to over $50,000 at local hospitals.There were 2 ER visits and one hospitalization for minor complications.

Gaillard-Campbell D, Gross TP, Webb L. Antibiotic Delivery via Hickman Catheter for the Treatment of Prosthetic Joint Infection. Orthopedics. 2021;44(3):e395-e401.

We report on a small series of 26 deep prosthetic joint infections treated with intraarticular antibiotics using direct infusion via a Hickman catheter. All 3 acute early infections were cured without implant removal. 70% of late acute infections were cured without implant removal. Chronic infections were treated inconjunction with a 2 stage exchange with a 90% success rate.

Gaillard-Campbell D, Gross TP. Early Cup shifts: A Previously unrecognized Phenomenon in Hip Arthroplasty. Acta Scientific Orthopaedics. 2020;3.1.

After instituting a rigorous standardized x-ray protocol intra operatively and postoperatively, we noticed that 0.9% of uncemented HRA acetabular components shifted within 6 weeks after implantation. All became radiographically stable after the initial shift. All of them shifted into a more horizontal position and did not violate the RAIL safe zone. Most were asymptomatic. 9.5% of these were revised, one for extreme position, one for late impingement symptoms. With a wedge-fit preparation technique the incidence of this problem was reduced to 0.2%.

Thomas P. Gross. Hip resurfacing: is female gender an absolute or relative contraindication? Annals of Joint. 2020. page 1-9.

Female sex is not a contraindication to hip resurfacing. THR has increasing failure rates in younger patients, but HRA does not. Traditionally women have higher failure rates than men with HRA and this was evident in my personal data as well. But young women with HRA still have similar durability outcomes as young women with THR. We have shown that a much higher incidence of dysplasia in women is one reason why women have a higher failure rate with HRA. Dysplasia is a more complex problem and is also associated with a higher failure rate in THR. We have elucidated the causes of higher failure rates in women than men in our HRA database, which were AWRF and failure of cup fixation on dysplastics. Others have also found a higher femoral neck fracture rate in women, but we have not seen this. Improvements in managing these problems (AWRF, cup fixation, and fractures) have equalized the durability outcomes in women with men. In addition other improvements (wedge-fit technique, uncemented femoral fixation, infection prevention, better soft tissue repair) have increased the overall success rate of MoM HRA from KM 89% to 99% over the last 20 years. Overall KM implant survivorship has increased more for women than men, equalizing implant survivorship since 2012. Now there is no reason to deny women the same proven advantages of HRA over THR which are: Better functional outcome including routine participation in impact sports, Better stability allowing routine participation in high ROM activities such as ballet, gymnastics, yoga and kayaking without fear of dislocation, better implant survivorship, lower rate of failures due to wear/corrosion (trunionosis in THR), bone preservation, and substantially lower 10-year all-cause mortality. In addition it has been shown that 85% of patients with both a THR and an HRA prefer the latter. Finally numerous professional athletes have returned to their sport after HRA, none have done this with THR.

Catherine Van Der Straeten and the International Hip Resurfacing Group. Hip resurfacing arthroplasty in young patients: international high-volume centres’ report on the outcome of 11,382 metal-on-metal hip resurfacing arthroplasties in patients ⩽50 years at surgery. Hip International 2020, 1-10.

A database of 11,062 MoM HRA cases in patients under 50 years age from 27 surgeons in 13 centers using 12 different implant systems was compiled. The KM implant survivorship was 95% at 10 years and 90% at 20 years. The three most common implants were BHR, Conserve Plus and Recap/Magnum. Two implant systems, the Cormet Corin 2000 and then Deputy ASR had inferior outcomes and were excluded. Durability was better in men than women and for OA compared to dysplasia. the most common identified failure modes were: Implant loosening (27.3% of failures), AWRF (10.3%), infection (8.1%), femoral neck fracture (7.9%).

This report demonstrated that MoM HRA had superior implant survivorship in young patients under 50 than those reported in registries for THR. Also it demonstrated that the outcomes are reproducible for multiple surgeons and implants.

Gaillard-Campbell MD, Gross TP. Prevention of Metallosis in Hip Resurfacing: Confirmation of the RAIL Guideline in 2466 cases. EC Ortrhopaedics 2019

This study served as a validation for the previously RAIL guideline for placing MoM HRA acetabular components published in 2013. In a separate consecutive series of 2466 MoM HRA cases, all acetabular components were placed in the RAIL safe zone and none failed due to AWRF. 56% of cases had ion testing . Of those, 98% had optimal ion levels and only one case had a level above 10ug/L. This confirms that the RAIL is indeed a safe zone for preventing AWRF in MoM HRA.

In this paper we first describe the technique for obtaining a NSIOR (normalized to standing intraoperative radiograph). Basically the OR table was rolled side to side to achieve neutral rotation and the X-ray tube was tilted cephelad/caudad to achieve pelvic tilt that was normalized to the properative standing pelvis x-ray. Spot digital x-rays are obtained until the standing appearance of the pelvis preoperatively is reproduced. The AIA is then measured to be sure it falls within the RAIL safe zone. Anteversion is set visually to be within + 10 ⁰ of the TAL. Also cup overhang anterior-inferior is ALWAYS avoided to prevent psoas impingement.

Additional Commentary: Anteversion is initially set by visually referencing the TAL (transverse acetabular ligament); if this is absent, we use the teardrop, which is  10⁰ retroverted wrt to the TAL. Now we also use Langton's classification of anteversion to qualitatively evaluate the NSIOR. We aim for a Langton A, accept a Langton B, and rarley accept a Langton C in a pelvis exhibiting extreme posterior tilt, but only if the we are well within the RAIL. These guidelines are harder to achieve in the smaller component sizes as well as in cases where extreme posterior pelvic tilt is seen on the standing x-ray. For ideal cup position we have also now added the criterion for burying the anterior-superior edge of the cup for preventing neck-on-cup impingement in flexion. This means that in cases with small sizes, shallow sockets, and extreme posterior pelvic tilt the socket must be reamer deeper to achive all the above criteria. We now recognize this purposefully prepare the socket deeper in these cases even prior to placing the trial implant. Not infrequently we penetrate the medial wall centrally to achieve these goals. To be comfortable with this approach requires considerable experience and careful technical execution.

Revised Criteria for Optimal HRA cup positioning:

• Place AIA within the RAIL safe zone using NSIOR.
• Set anteversion 0 to -10⁰ from TAL (or +10⁰ to 0 from teardrop) visually.
• Ensure Langton A or B anteversion on NSIOR, occasionally Langton C on a case of extreme PPT as long as AIA is well within RAIL.
• Do not allow anterior-inferior cup overhang to protect psoas from cup edge (releae psoas from LT in the extremely rare cases where this is not possible).
• Avoid anterior-superior cup overhang to prevent neck-on-cup impingement in flexion.

Su EP, Morgenstern R, Khan I, Gaillard MD, Gross TP. Hip resurfacing arthroplasty for end-stage arthritis caused by childhood hip disease. HIP International. 2019.

In cases with severe deformities (59 Legg Perthes and 32 Slipped epiphysis) KM implant survivorship was 94% at 11 years in these complex cases. Leg lengths were not equalized, but discrepency was significantly decreased

Gaillard-Campbell DM, Gross TP. Femoral Fixation Methods in Hip Resurfacing Arthroplasty: An 11-Year Retrospective Comparison of 4013 Cases. J Arthroplasty. 2019;34(10):2398-405.

At 10 years the rate of femoral loosening was reduced from 1% to 0 when comparing cemented to uncemented fixation with the Recap implant. The rate of early femoral failure also was reduced from 0.8% to 0.3%, but this likeley was due to the introduction of a bone management protocol.

Gaillard-Campbell DM, Gross TP. Optimizing Acetabular Component Bone Ingrowth: The Wedge-Fit Bone Preparation Method. Adv Orthop. 2019;2019:9315104.

A new method of acetabular bone preparation was introduced. Prior to 2012 all acetabulae were prepared using a 1mm underream. Therefter the wedge-fit method was introduced. Patients with good bone ( Tscore > -1.0 ) were reamed line-to-line, those with poor bone were under reamed 1mm . All sockets were apex reamed 1-2mm with a smaller reamer. This encouraged the implant to load the peripheral bone and wedge in with loading, rather than bottoming out on the apex. We found that this method reduced the rate of failure of ingrowth from 0.5% to less than 0.1%. The rate of cup shifts was reduced from 1.1% to 0.4%. The rate of unexplained pain was reduced from 2.6% to 1.3% suggesting that some cases of unexplained pain may be unrecognized cases of acetabular failure of ingrowth.

Eric Robinson, Dani Gaillard-Campbell , and Thomas P. Gross. Acetabular Debonding: An Investigation of Porous Coating Delamination in Hip Resurfacing Arthroplasty. Advances in Orthopaedics 2018.

In 371 cases using the hybrid Corin Cormet 2000 MoM HRA system, 13 (3.5%) acetabular components failed due to debonding of the titanium plasma spray porous coating from the substrate cast cobalt chrome component between 8-12 years postoperatively. There were no debonding failures in a comparison group of 728 Biomet Recap/Magnum MoM HRA implants. Both groups had minimum 10 years of follow-up. Other acetabular failure modes including failure of ingrowth, loosening without debonding and AWRF were no different between the two groups. Most of the Cormet debonding failures occurred in those that were implanted in 2002. The failures typically presented in patients with many years of excellent functioning HRA, followed by a 1-3 months prodrome of mild symptoms before a sudden catastophic failure when the cup spins out. Porous coating application was outsourced to different subcontractors for the 371 implants we used, but the company would not disclose serial numbers coated by different subcontractors. We suspect that one of the subcontractors may have done a suboptimal job of the coating process.

Additional Commentary: To date approximately 5% of Corin cups debonded between 8-12 years. Thereafter this failure mode ceased to occur. The overall 25 year KM implant survivorship of the Corin system is currently 81%. Of the nearly 7400 uncemented Biomet Magnum cups implanted to date only one has failed due to debonding. Maximum follow-up of this implant is now 20 years with a 95% 20-year KM survivorship of the hybrid implant and a 98% 18-year survivorship of the uncemented implant. It is very clear now that the inherent concept of adhering titanium plasma spray to a cobalt chrome implant is sound, but it is not clear if the ASTM standard is adequate or not. The process that Biomet uses is sound, the process that Corin used was not. We do not know if Corin failed to meet the ASTM or if Biomet exceeded the standard significantly. This information remains proprietary.

O'Leary RJ, Gaillard MD, Gross TP. Comparison of Cemented and Bone Ingrowth Fixation Methods in Hip Resurfacing for Osteonecrosis. J Arthroplasty. 2017;32(2):437-46.

For the diagnosis of osteonecrosis (ON), 8-year KM implant survivorship at 8 years was 100% using an uncemented Recap femoral component, compared to 91% for a cemented femoral component. There were 103 Recap UC cases, 43 Corin cemented , and 32 Recap cemented cases. 5.5% of all HRA cases in our database were done for ON. 80% were men, mean age was 45 years.

Gaillard MD, Gross TP. Metal-on-metal hip resurfacing in patients younger than 50 years: a retrospective analysis : 1285 cases, 12-year survivorship. J Orthop Surg Res. 2017;12(1):79.

Generally the failure rate of THR is higher in younger patients. We demonstarted that this is not true for HRA. KM implant survivorship in our younger patients (<50 years) was 96.5% @ 10 years and 96.2% at 12 years in a cohort of 1285 MoM HRA. This was no different than the durability in the remaining 1984 older patients in our database. Our reported durability exceeds the NICE criteria set for older patients in the British Registry (95% @ 10 years). It far exceeds durability in younger THR patients fron the Swedish Registry (83% @ 10 years). There were only 4 (0.3%) AWRF in the cohort, all before 2009. At this time women still had a higher failure rate than men, but the gap was narrowing.

Gaillard EB, Gaillard MD, Gross TP. Interventions for Improving Hip Resurfacing Outcomes in Women: A High-Volume, Retrospective Study. J Arthroplasty. 2017;32(11):3404-11.

We found that the higher failure rate in women could be explained by a greater number of adverse wear related failure (AWRF) and a higher rate of failure of acetabular ingrowth (FAI). The former was due to the fact that women used smaller implant sizes which had a lower coverage arc and were more prone to edge loading prior to the development and implementation of the RAIL (relative acetabular inclination limit) guideline in 2009. FAI occurred more often because dysplasia was more prevalent in women. Failure of fixation occurred more often in oval, shallow sockets until we began using the supplemental fixation (trispike) cup in 2007. The femoral loosening rate also declined after introducing the uncemented femoral component in 2007, but this improvement helped men and women equally. 8 - year KM implant survivorship improved from 90% to 98% in women who had HRA after 2008. This higher risk younger cohort is now projected to meet NICE criteria for implant survivorship for elderly patients with THR.

Gaillard MD, Gross TP. Reducing the failure rate of hip resurfacing in dysplasia patients: a retrospective analysis of 363 cases. BMC Musculoskelet Disord. 2016;17:251.

We analyzed the implant survivorship in 363 dysplasia cases with MoM HRA. We compared outcomes before and after 2008. After this date we had both a trispike acetabular component with supplemental fixation which we used in the most deficient 5% of dysplasia cases, and we had developed the RAIL criteria and a NSIOR (normalized to standing intraoperative radiograph) to place acetabular components in the safe zone to avoid edge-loading. After 2008 seven-year KM implant survivorship increasaed from 89% to 99% in dysplastic patients. 72% were women, mean age was 50 years.

Gross TP, Liu F. Outcomes After Revision of Metal-on-Metal Hip Resurfacing Arthroplasty. Journal of Arthroplasty. 2014.

We found a 97% 5-year KM implant survivorship for revision of MoM HRA in 58 cases. The causes of failure were femoral neck fracture (16), acetabular loosening (16), late femoral loosening (11), AWRF(7), Head collapse (4), infection ( 3) , unexplained pain (1). In 95% the revision bearing was MoM. The only problematic group was the acetabular loosening group which had a 6% (2/16) failure rate. All AWRF were revised to another MOM implant. All were successful. mean age at the time of revision was 53 years.

Gross TP, Liu F. Current status of modern fully porous coated metal-on-metal hip resurfacing arthroplasty. J Arthroplasty. 2014;29(1):181-5.

The first 1000 cases of fully uncemented Recap/magnum HRA are found to have a 5-year 97.5% KM implant survivorship. the rate of femoral neck fracture was 0.3% the rate of head collapse was 0.2%, There were no cases of failure of ingrowth or of loosening.

20.1

Liu F, Gross TP. A safe zone for acetabular component position in metal-on-metal hip resurfacing arthroplasty: winner of the 2012 HAP PAUL award. J Arthroplasty. 2013;28(7):1224-30.

This represents the first and currently the only scientifically validated safe zone for correctly placing acetabular components that has ever been published for any type of hip arthroplasty. We developed the RAIL (relative acetabular inclination limit) safe zone from a data set of 761 MoM HRA with measured standing AP pelvis x-rays, ion levels and confirmed wear failures. All MoM HRA implants have subhemispherical bearings. The first generation, including Cormet, Recap/Magnum, BHR and Conserve Plus, all had a variable coverage arc. In the Recap/Magnum system the coverage arc varied from 155 to 164 degrees. The coverage arc increases with bearing size. This is the feature that makes the smaller implants more prone to edge load in steeper positions. However, if the smaller sizes are placed more horizontally, edge-loading and AWRF (adverse wear related failure) can be prevented. This paper presents a safe zone for placing all Recap/Magnum implants based on their bearing size (coverage arc) that is 99% effective in preventing hgh ion levels (above 10ug/L) and AWRF. The caveats are that anteversion cannot be excessive (within 10 degrees of the TAL, or Langton grade A or B) and that implant positions are measured on a standing neutrally rotated pelvis x-ray. A 3-D plot demonstrated that a combination of smaller bearing size (lower coverage arc) and steeper inclination angle resulted in an increased probablity of ion levels being measured above 10 ug/L. A Straight line relationship exists between bearing size (coverage arc) and maximum allowable AIA (acetabular inclination angle) which we designated the RAIL (relative acetabular inclination limit). The smallest implant with bearing size 40mm must be placed with a standing AIA below 32, while the largest size 60mm can be placed as high as 59 degrees. There is no lower limit on the safe zone to prevent AWRF. Cups placed too horizontal due not ever result in AWRF, they may, however, develop other problems such as symptomatic impingement. Of the 451 cases that were in the safe zone, 0.4% had an ion level above 10ug/L and none had AWRF or instability. In the 310 case outside the safe zone, 18 (5.8%) had ion levels above 10ug/L, 8 (2.6%) had AWRF and 2 (0.6%) had dislocations.

On the other hand, the endlessly referenced "Lewenik safe zone" was never supported by the data presented in the original article and has been proven to be unsafe by numerous authors.

Additional Commentary: We continue to track all cases in my database of over 7700 MoM HRA. We have also retrospectively reviewed all cases done prior to this study. To date not a single case placed within the RAIL safe zone has ever resulted in an AWRF. There have been no cases done after 2009 that were inadvertently placed outside the RAIL safe zone (Over 4000 consecutive cases). There have been 10/328 (3%) AWRF in implants placed before 2010 where the components were retrospectively found to be outside the RAIL safe zone. The RAIL safe zone is very safe.

Gross TP, Liu F. Incidence of adverse wear reactions in hip resurfacing arthroplasty: a single surgeon series of 2,600 cases. Hip Int. 2013;23(3):250-8.

The rate of AWRF in a single surgeon series of 2600 cases was KM 1% at 10 years, 0.3% in men, 2.6% in women, and 9% for cases done for dysplasia. All failures had a bearing size < 48mm, had ion levels > 15 ug/L, and had AIA > 50 degrees. All had severe grey metallosis seen in surgery, there were no failures due to "pseudotumors" without metallosis present.

Gross TP, Liu F. Total knee arthroplasty with fully porous-coated stems for the treatment of large bone defects. J Arthroplasty. 2013;28(4):598-603.

28 cases of revision or complex primary TKA with fully porous coated stems are described. 100% of 34 fully prous stems achieved stable bone ingrowth. One failed due to debonding and subsequent loosening of the porous stem. Three failed due to deep infection.

Gross TP, Liu F, Webb LA. Clinical outcome of the metal-on-metal hybrid Corin Cormet 2000 hip resurfacing system: an up to 11-year follow-up study. J Arthroplasty. 2012;27(4):533-8 e1.

91% 10-year KM implant survivorship for the Hybrid Corin MoM HRA. This single surgeon series of 373 cases represents his learning curve with HRA as well as the largest cohort of the the first FDA IDE study that resulted in approval of a MoM HRA in the US. A learning curve of up to 200 cases was suggested. The most common failure modes were loosening of the cemented femoral component (2.9% at mean 3 years), femoral neck fractures (1.3% at mean 3.8 months), acetabular loosening (1.3% at mean 4 years), AWRF (0.5% at 8 years).

Gross TP, Liu F. Hip resurfacing with the Biomet Hybrid ReCap-Magnum system: 7-year results. J Arthroplasty. 2012;27(9):1683-9 e2.

96.4% 7-year KM implant survivorship is seen in 740 cases using the Recap/Magnum Hybrid MoM HRA system. Most common failure modes were acaetabular loosening (1.1%), femoral neck fracture (0.8%), femoral loosening (0.5%), deep infection ( 0.3%), AWRF (0.3%). Women had twice the failure rate compared to men (5.6% vs 2.5% ), mostly due to acetabular fixation in dysplastic cases.

Gross TP, Liu F. Prevalence of dysplasia as the source of worse outcome in young female patients after hip resurfacing arthroplasty. Int Orthop. 2012;36(1):27-34.

The 7-year KM implant survivorship for MoM HRA in patients with dysplasia increased from 89% to 99% after 2008, by which time four major changes in technique had been implemented. These changes included:

#1: Bone management program reduces early femoral failure by modifying postoperative instructions based on the two proven risk factors for early femoral failure, obesity and low bone density.

#2: Uncemented femoral component

#3: Supplemental fixation acetabular components for more severely deformed acetabular components

#4. Wedge-fit acxetabular preparation for all the remaining sockets

Overall 12% of all our HRA cases are for dysplasia. 70% are women. The mean age is 50 years.

Gross TP, Liu F. Comparative study between patients with osteonecrosis and osteoarthritis after hip resurfacing arthroplasty. Acta Orthop Belg. 2012;78(6):735-44.

The KM implant survivorship at 10 years was 88% for 122 MoM HRA done for osteonecrosis (ON) as compared with 100% for a propensity matched group of cases done for osteorthritis (OA). Femoral loosening occurred in 4/122 (3.3% ) of ON cases and in no OA cases. There were no failures in the 47 uncemented femoral components done for ON. Higher failure risk also correlated with increased Ficat stage of ON.

Gross TP, Liu F. Risk factor analysis for early femoral failure in metal-on-metal hip resurfacing arthroplasty: the effect of bone density and body mass index. J Orthop Surg Res. 2012;7:1.

Low bone density and BMI >29 were the only independent risk factors for early femoral failure (EFF, femoral neck fractures plus head collapse) in a multivariate analysis of 373 MoM HRA cases. Sex and Age were found to be dependent risk factors while bone density was the independent risk factor. Patients with a femoral neck T-score < -1.5 were found to have a risk of EFF of 7.9%. Those with a BMI > 29 had a risk of 2.9%. Those with both a low bone density and obese were found to have a risk of 25%. Femoral fixation type, component size, or preoperative diagnosis also did not affect EFF rate.

Sayeed SA, Johnson AJ, Stroh DA, Gross TP, Mont MA. Hip resurfacing in patients who have osteonecrosis and are 25 years or under. Clin Orthop Relat Res. 2011;469(6):1582-8.

We found a KM 100% 7-year implant survivorsip in a small group of 20 MoM HRA in a very young cohort of ON patients.

Johnson AJ, Zywiel MG, Maduekwe UI, Liu F, Mont MA, Gross TP. Is resurfacing arthroplasty appropriate for posttraumatic osteoarthritis? Clin Orthop Relat Res. 2011;469(6):1567-73.

We found a KM 90% 5-year implant survivorship in a small group of 29 hips that had MoM HRA for posttraumatic arthritis.

Gross TP, Lu F, Webb L. Comparison of unilateral and rapidly staged bilateral hip resurfacing arthroplasty. Acta Orthop Belg. 2011;77(2):203-10.

Rapidly staged bilateral MoM HRA consisted of performing the operations two days apart and keeping the patient in hospital for a total of 5 days. A comprehensive blood management program is described which includes preoperative optimization (including EPO if needed) as well as a minimally invasive operative approach, an intraoperative tissue sealer, epinephrine irrigation, platelet concentrate with thrombin, postoperative oral iron and a low transfusion trigger ( Hg<7.0 or symptomatic). Tranexamic acid was not used. Postoperative anticoagulation with Arixtra was given. 25 patients with rapidly staged bil;ateral HRA were compared to 100 consecutive unilateral cases all done with a two night overnight hospital stay. No transfusions were needed in either group. There were no cases with symptomatic anemia. The lowest hemoglobin recorded was on POD#2 in a bilateral patient at 7.2 g/dL Complications were no different between the two groups.

Gross TP, Liu F, Webb L. Intraoperative radiographs for placing acetabular components in hip resurfacing arthroplasty. Clin Orthop Relat Res. 2011;469(6):1554-9.

Simple single shot intraoperative radiographs were performed to ensure that AIA (acetabular inclination angle) was between 30-50 degrees on all cases. In 100 study cases, only one AIA was above 50 degres (51⁰), while in the prior control group where no intraoperative x-rays were taken, there were 16/100 with AIA above 50 degrees (51⁰ - 57⁰). In the study group we noted 2 cases of cup shift between the intraoperative and postoperative radiographs, both into a more horizontal position. This is the first time we became aware of the phenomenon of postimplantation cup shifts. After an initial shift, these implants subsequently achieved ingrowth and were successful.

Additional Commentary: This study was conducted when we had become aware of AWRF (adverse wear related failure) being related to steeper cup positions, but we had not yet developed the more nuanced understanding of edge loading related to variable cup coverage arc based on size. Soon after this we developed the more sophisticated RAIL (relative acetabular inclination limit) safe zone which also required a more advanced method of checking intraoperative AIA. We called this the NSIOR (normalized to standing intraoperative radiograph).

Gross TP, Liu F. Is there added risk in resurfacing a femoral head with cysts? Journal of Orthopaedic Research. 2011;6:55:1-7.

There is no added risk of early femoral failure with femoral head cysts regardless of size as long as they are cavitary defects that can be bone grafted prior to cementation or uncemented fixation. 117 cases had cysts > 1cm measured intraoperatively. These were compared to 117 propensity matched cases without cysts done at the same historical time. There were 3 femoral failures in the study group and none in the control group (p=0.08). follow-up was 2-5 years. Cases of osteonecrosis were excluded. Approximately half of the cases in each group used uncemented components. No difference in failure was seen for method of femoral fixation.

Compared to Amstutz and Beaule SARI study, we had more cases, we evaluated cyst size intraoperatively rather than retrospectively on preoperative x-rays, we had a slightly longer followup, a lower femoral failure rate, and we never cemented stems or filled cysts with cement.

Additional Commentary: Our conclusion is that as long as osteoarthritic cavitary cysts up to 4cm³ seen intraoperatively are filled with bone graft rather than cement, early femoral failure rate is not increased. Osteonecrosis is a different problem because all dead bone is typically not removed, and defects are typically segmental, making it impossible to graft when using cement. These are best handled by uncemented fixation with bone grafting.

Gross TP, Liu F. Comparison of fully porous-coated and hybrid hip resurfacing: a minimum 2-year follow-up study. Orthop Clin North Am. 2011;42(2):231-9, viii-ix.

There was no difference seen in the short-term femoral failure rate between uncemented and cemented femoral fixation using the same Recap/Magnum MoM HRA system. 191 fully porous MoM HRA were compared to 96 hybrid implants at a minimum of 2 years follow-up. There were no cases where uncemented femoral fixation had to be abandoned in surgery due to inadequate initial press-fit. In the UC group there were 2 revisions for femoral neck fracture and 2 for femoral head collapse, in the hybrid group there was one revision for fracture and one for collapse. KM implant survivorship in both groups at 3 years was 98%.

Gross TP, Liu F. The first 100 fully porous-coated femoral components in hip resurfacing. Bull NYU Hosp Jt Dis. 2011;69 Suppl 1(Suppl 1):S30-5.

For the first 100 fully uncemented MoM HRA KM implant survivorship at 3 years was 98%. There was one femoral neck fracture at 2 months and one femoral loosening at 12 months.

Gross TP, Liu F. Minimally Invasive Psterior Approach for Hip Resurfacing arthroplasty. Techniques in Orthopaedics. 2010;25:39-49.

The surgical Technique of a minimally invasive (MIT) posterior approach for hip resurfacing is described using a four inch incision. No differences in outcome and complcations were seen between the last 100 standard approaches and the first 100 MIT cases, except for a slightly higher HHS at final follow-up for the MIT group ( 96 vs 92, p<0.04). The opertive time and hospital stay were the same. There were no transfusions in either group.

Gross TP, Liu F. Metal-on-metal hip resurfacing with an uncemented femoral component. A seven-year follow-up study. J Bone Joint Surg Am. 2008;90 Suppl 3:32-7.

The authors first experience with MoM HRA is reported. We report on the first 20 hips done with a fully uncemented Corin MoM HRA system. Mean follow-up was 7.4 years. There were two acetabular failures, one failure due to late hematogenous infection and one due to unexplained pain. One patient was lost to follow-up after 3 months.