Outcome of total hip arthroplasty as a salvage procedure for failed infected internal fixation of hip fractures

Background:

Failed infected internal fixation produces significant pain and functional disability. In infected internal fixation of hip fractures with partial or complete head destruction, total hip arthroplasty (THA) can be technically challenging; however, it restores hip biomechanics. The present study is to evaluate the results and assess the complications of THA following failed infected internal fixation of these fractures.

Materials and Methods:

A retrospective review of prospectively collected data in a tertiary healthcare center was performed of 20 consecutive patients of THA following failed infected internal fixation operated between September 2001 and November 2007. There were 11 dynamic hip screw failures for intertrochanteric fractures, 6 failed osteotomies following transcervical fractures, and 3 failed screw fixations for transcervical fractures.

Results:

The average age of the patients was 48.5 years (range 28-70 years) and the average followup period was 6.5 years (range 3.5-10.5 years). An indigenously designed cement spacer was used in a majority of patients (n = 15). The custom-made antibiotic impregnated cement spacer was prepared on-table, with the help of a K-nail bent at 130°, long stem Austin Moore''s prosthesis (n=1), Charnley''s prosthesis (n=1), or bent Rush nail (n=1). The antibiotic mixed cement was coated over the hardware in its doughy phase and appropriately shaped using an asepto syringe or an indigenously prepared spacer template. Nineteen of the 20 patients underwent two-stage revision surgeries. The average Harris hip score improved from 35.3 preoperatively to 82.85 postoperatively at the last followup. A significant difference was found (P < 0.0001). None of the patients had recurrence of infection.

Conclusions:

The results were comparable to primary arthroplasty in femoral neck fractures. Thus, THA is a useful salvage procedure for failed infected internal fixation of hip fractures.     

Total hip arthroplasty for failed aseptic Austin Moore prosthesis

Background:

Though Austin Moore (AM) replacement prosthesis has fairly good short term results for intracapsular femoral neck fractures in the elderly, it still is a compromised option and has a high failure rate in the long run. The objective of the present retrospective study is to analyze the functional outcome, assess survivorship of revision total hip arthroplasty (THA) at mid to long term followup, and evaluate intraoperative difficulties faced during conversion of failed aseptic AM prosthesis to cemented THA.

Materials and Methods:

Eighty-nine cemented THA surgeries for failed AM prosthesis were performed between 1986 and 2005. AM failures were classified into seven groups on the basis of mode of failure. Infected failures were excluded from the study. There were 35 men and 54 women in the study group. The mean age was 68 years (range 57–91 years). Mean followup was 8 years (range 5–13 years).

Results:

Average Harris Hip Score improved from 65 preoperatively (range 42–73) to 87 (range 76–90) at 1 year postoperatively and to 86 (range 75–89) at the last followup. The overall complication rate was 4.5%.

Conclusion:

Conversion THA is an excellent treatment strategy for symptomatic failed AM hemiarthroplasty in terms of pain relief and restoration of function and mobility as near as possible to the preinjury level. Also, hemiarthroplasty should not be used in physically active patients, even in elderly individuals. Careful patient selection for hemiarthroplasty versus THA is vital and may decrease the incidence of complications and ameliorate the outcomes in the treatment of intracapsular femoral neck fractures.     

Hip arthroplasty in failed intertrochanteric fractures in elderly

Background:

Failed intertrochanteric fractures in elderly patients are surgical challenge with limited options. Hip arthroplasty is a good salvage procedure even though it involves technical issues such as implant removal, bone loss, poor bone quality, trochanteric nonunion and difficulty of surgical exposure.

Materials and Methods:

30 patients of failed intertrochanteric fractures where hip arthroplasty was done between May 2008 and December 2011 were included in study. 13 were males and 17 were females with average age of 67.3 years. There were 2 cemented bipolar arthroplasties, 19 uncemented bipolar, 4 cemented total hip arthroplasty and 5 uncemented total hip arthroplasties. 16 patients had a trochanteric nonunion, which was treated by tension band principles. Total hip was considered where there was acetabular damage due to the penetration of implant.

Results:

The average followup was 20 months (range 6-48 months). Patients were followed up from 6 to 48 months with average followup of 20 months. None of the patients were lost to followup. There was no dislocation. All patients were ambulatory at the final followup.

Conclusion:

A predictable functional outcome can be achieved by hip arthroplasty in elderly patients with failed intertrochanteric fractures. Though technically demanding, properly performed hip arthroplasty can be a good salvage option for this patient group.     

Total hip arthroplasty (S-ROM stem) and subtrochanteric osteotomy for Crowe type IV developmental dysplasia of the hip

Background:

Developmental dysplasia of the hip (DDH) in adults with severe pain and disability is best treated by total hip arthroplasty (THA). The purpose of this study was to retrospectively evaluate the outcomes of subtrochanteric shortening osteotomy combined with THA using S-ROM stem for those severe patients with a special focus on the effect of two shapes in the subtrochanteric osteotomy ends: Oblique and transverse.

Materials and Methods:

Twenty one cases with mean age of 43.6 years who met inclusion criteria and were operated between February 2007 and February 2012 were included in the study. Those cases had been divided into two groups (oblique vs. transverse) and all records between the two groups were analyzed.

Results:

The Harris hip score significantly improved from 30.6 (range 18–59) preoperatively to 91.2 (range 87–98) postoperatively by the latest followup. Complications including one deep venous thrombosis, one intraoperative fracture of femur and two dislocations occurred while they were addressed properly afterward. The oblique group showed significant advantages in operative time, union time and additional fixation in comparison with the transverse group.

Conclusions:

In the primary THA for the treatment of irreducible DDH, subtrochanteric oblique osteotomy combined with the freely-rotatable S-ROM stem provided favorable short term outcomes by affording both morphological and functional advantages.     

Modified minimally invasive two-incision total hip arthroplasty using large diameter femoral head

Background:

Minimally invasive (MI) total hip arthroplasty (THA) is an alternative to standard THA, but has created much controversy among orthopedic surgeons. The authors modified the original minimally invasive two-incision THA technique and used large-diameter (32 mm, 36 mm) ceramic-on-ceramic articulation.

Materials and Methods:

One hundred and seventy patients that underwent unilateral MI two-incision THA were retrospectively reviewed, and surgical morbidity, functional recovery, radiological properties, and complications were assessed.

Results:

Mean Harris hip score (HHS) improved from 41.8 to 96.1 at last followup, and mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score from 66.2 to 26.9. The mean lateral opening angle of the acetabular component was 38.2° and the mean stem position was valgus 1.9°. There was an intraoperative femur fracture and one revision surgery due to stem subsidence. No patient had dislocation.

Conclusions:

Our data suggest that this modified technique combined with large ceramic femoral head is safe and reproducible in terms of achieving proper implant positioning and early functional recovery.     

Conversion of failed hemiarthroplasty to total hip arthroplasty: A short to mid-term follow-up study

Background:

The conversion of hemiarthroplasty (unipolar or bipolar) of the hip to total hip replacement has been reported to be associated with very high rates of intra- and postoperative complications. We present a prospective analysis of the outcome of conversion surgery in patients with failed hemiarthroplasty.

Materials and Methods:

Forty-four cases, 30 women and 14 men, average age 62 years (range 42-75 years) of failed hemiarthroplasty were converted to total hip replacement between January 1998 and December 2004. Groin pain was the main presenting complaint in the majority of the patients (24 out of 44). Six patients had infection and were operated with staged procedure. All acetabular and the majority (86.5%) of femoral components used in our series were uncemented.

Results:

After an average follow-up of 6.4 years (range, two to nine years) Harris hip scores improved from 38 (range 15-62) preoperatively to 86 (range 38 to 100) and 22 (50%) patients were community ambulators without support while 17 (38%) needed minimal support of cane. Fifteen out of 18 (83%) patients who had isolated groin pain preoperatively experienced no pain postoperatively while three patients (17%) reported only partial improvement. Intraoperative and postoperative complications included iatrogenic fracture of the femur in two, femoral perforation in two, partial trochanteric avulsion in two, fracture of the acetabular floor in three hips, and postoperative dislocation in one. None of these complications resulted in a poor long-term outcome. The rate of loosening in our series was 2.3% (one out of 44) after a mean follow-up of 6.4 years with a mean survival of 97.4% at 72 months.

Conclusion:

Conversion of symptomatic hemiarthroplasty to total hip arthroplasty is a safe option that gives good functional results, with marginally higher rates of intra-operative complications. The patients should be warned of the possibility of incomplete relief of groin pain postoperatively.     

Modified Girdlestone arthroplasty and hip arthrodesis using the Ilizarov external fixator as a salvage method in the management of severely infected total hip replacement

Background:

Resection arthroplasty or hip arthrodesis after total hip replacement (THR) can be used to salvage the limb in case with deep infection and severe bone loss. The Ilizarov fixator provides stability, axial correction, weight-bearing and good fusion rates.

Materials and Methods:

We retrospectively assessed the outcomes of 37 patients with severe periprosthetic infection after THR treated between 1999 and 2011. The treatment included implant removal, debridement and a modified Girdestone arthroplasty (29 cases) or hip arthrodesis (seven cases) using the Ilizarov fixator. The Ilizarov fixation continued from 45 to 50 days in the modified arthroplasty group and 90 days in the arthrodesis group. One case was treated using the conventional resection arthroplasty bilaterally.

Results:

Eighteen months after treatment, infection control was seen in 97.3% cases. Six hips were fused as one patient died in this group. Limb length discrepancy (LLD) averaged 5.5 cm. The Harris hip score ranged from 35 to 92 points. Hip joint motion ranged from 10° to 30° in the modified arthroplasty group. All subjects could walk independently or using support aids. No subluxation or LLD progression was observed.

Conclusion:

The modified Girdlestone arthroplasty and hip arthrodesis using the Ilizarov apparatus results in sufficient ability for ambulation and good infection control in cases of failed THR associated with severe infection.     

Delayed Total Hip Arthroplasty for Failed Acetabular Fractures: The Influence of Initial Fracture Management on Outcome After Arthroplasty

Background

Total hip arthroplasty (THA) provides a successful salvage option for failed acetabular fractures. The complexity of arthroplasty for a failed acetabular fracture will depend on the fracture pattern and the initial management of the fracture. Our objective was to compare the midterm outcome of THA between patients who presented with failed acetabular fractures following initial surgical or nonsurgical treatment.

Results of uncemented distal locked prosthesis in revision hip arthroplasty with proximal femoral bone loss: A retrospective study

Introduction:

Management of bone loss is a challenge in revision total hip arthroplasty (THA). A retrospective review was performed to study the use of uncemented distal locked prosthesis in cases with proximal femoral bone loss.

Materials and Methods:

Uncemented stems with distal interlocking were used in 65 hips during revision THAs with 38 hips having Paprosky IIIB/IV defects between January 1998 and February 2004. There were 48 males and 17 females in the study with an average age of 53 years (range 30-80 years). Radiographic and clinical outcome evaluation using the Harris hip score (HHS) were performed.

Results:

An improvement in HHS (mean: 33 points) was observed at final followup (mean: 9 years). Regeneration of proximal bone stock was observed without signs of loosening or subsidence and none of the stems were revised. Three patients developed recurrent dislocation while one had a stem subsidence of 1cm following removal of interlocking bolts.

Conclusion:

Uncemented distal locked prosthesis provide adequate stability in revision THA, aiding the reconstruction of bony deficiencies while avoiding the disadvantages of fully porous or cemented implants.     

The Conversion Rate of Bipolar Hemiarthroplasty after a Hip Fracture to a Total Hip Arthroplasty

Background

Bipolar hip hemiarthroplasty is used in the management of fractures of the proximal femur. The dual articulation is cited as advantageous in comparison to unipolar prostheses as it decreases acetabular erosion, has a lower dislocation rates and is easier to convert to a total hip arthroplasty (THA) should the need arise. However, these claims are debatable. Our study examines the rate of conversion of the bipolar hemiarthroplasty to THA and the justification for using it on the basis of future conversion to THA.

Methods

All cases of bipolar hemiarthroplasty performed in our unit for hip fractures over a 9-year period (1999-2007) were reviewed. Medical notes and radiographs of all patients were reviewed, and all surviving patients that were contactable received a telephone follow-up.

Results

Of all 164 patients reviewed with a minimum of 1 year from date of surgery, 4 patients had undergone a conversion of their bipolar prosthesis to THA. Three conversions were performed for infection, dislocation, and fracture. Only one (0.6%) conversion was performed for groin pain.

Conclusions

Our study show that bipolar hemiarthroplasties for hip fractures have a low conversion rate to THAs and this is comparable to the published conversion rate of unipolar hemiarthroplasties.     

Functional outcome following a large head total hip arthroplasty: A retrospective analysis of mid term results

Background:

One of the reasons that hip resurfacing and large head metal on metal (MOM) total hip arthroplasty (THA) became popular in Asia was the possible increased range of movement and thereby improved function of the hip joint. Due to concerns of MOM articulation an alternative bearing was sought. Hence, a shift from large head MOM to large head ceramic on ceramic (COC) was made. The aim of this study was to compare the functional outcome including range of motion (ROM) and dislocation rates following large head MOM and large head COC THA.

Materials and Methods:

Retrospectively, 39 primary THA with large head MOM with a mean age of 56 years (range 36-72 years) and average followup of 54 months (range 38-70 months) were compared with 23 primary THA with large head COC bearing with a mean age of 48 years (range 36-68 years) and an average followup of 18 months (range 12-26 months). Functional outcome was assessed using the Modified Harris Hip Score. Dislocation rate and ROM were compared.

Results:

Global ROM averaged 248 degrees with MOM group and 252 degrees with the COC group. One patient with metal bearing had dislocation at an average 3 year followup which required revision THA while there were no complications in the COC group. MHHS averaged 89 points in MOM and 94 in COC THR.

Conclusion:

This study has shown that large head ceramic on ceramic THA is a good alternative to large head metal on metal THA with comparable dislocation rates and range of movements and without complications of metallosis in Asian patients.     

Minimally invasive total hip arthroplasty with the anterior approach

Background:

Total hip athroplasty with the anterior surgical approach is advised because the dissection is entirely within intermuscular planes. In this report we describe a minimally invasive technique of anterior total hip arthroplasty, with the early outcomes.

Materials and Methods:

The technique of minimally invasive total hip arthroplasty with anterior approach (Smith-Petersen) is described. We reviewed data on 100 consecutive patients who underwent anterior total hip arthroplasty with uncemented components. Mean patient age was 61 years (range 33-91). Mean patience BMI 29.8 (range 18.1-51.8).

Results:

Minumum follow up duration is 10 months. The mean duration of surgery was 53 min (range 34-87) with mean blood loss 185 cc (range 65-630), and the mean incision length was 10.4 cm. Clinical and radiographic outcomes were similar to historical outcomes of standard total hip arthroplasty.

Conclusions:

With proper surgeon training, minimally invasive total hip replacement with the anterior surgical interval is safe and efficacious.     

A modified two-incision technique for primary total hip arthroplasty

Background:

Minimally invasive surgery can be technically demanding but minimizes surgical trauma, pain and recovery. Two-incision minimally invasive surgery allows only intermittent visualization and may require fluoroscopy for implant positioning. We describe a modified technique for primary total hip arthroplasty, using two small incisions with a stepwise approach and adequate visualization to reliably and reproducibly perform the surgery without fluoroscopy.

Materials and Methods:

One hundred and two patients with an average age of 60 years underwent modified two-incision minimally invasive technique for primary THA without fluoroscopy. The M/L taper femoral stem (Zimmer, Warsaw, IN) and Trilogy (Zimmer) hemispherical titanium shell, with a highly cross-linked polyethylene liner, was used. Operative time, blood loss, postoperative hospital stay, radiographic outcomes and complications were recorded.

Results:

The mean operating time was 77 min. The mean blood loss was 335 cc. The mean hospital stay was 2.4 days. Mean cup abduction angle was 43.8°. Mean leg length discrepancy was 1.7 mm. Thirteen patients had lateral thigh numbness and two patients had wound complications that resolved without any treatment.

Conclusion:

A modified two-incision technique without fluoroscopy for primary total hip arthroplasty has the advantage of preserving muscles and tendons, shorter recovery and return to function with minimal complications. Provided that the surgeon has received appropriate training, primary total hip arthroplasty can be performed safely with the modified two-incision technique.     

Mid term results of total hip arthroplasty using polyethylene-ceramic composite (Sandwich) liner

Background:

Ceramic-on-ceramic (COC) couplings are an attractive alternative bearing surfaces that have been reported to eliminate or reduce problems related to polyethylene wear debris. However, the material in total hip arthroplasty (THA) remains one of the major concern regarding the risk of fracture. The present study aims at reporting the fracture rate of bearings in a series of COC THAs with the use of a sandwich liner and attempt to detect the relative risk factors, the possible cause and assess the clinical results.

Materials and Methods:

We retrospectively evaluated 153 patients (163 hips) using the sandwich liner COC THA between 2001 and 2009. Patient assessment was based on demographic factors, including age, weight, gender and body-mass index (BMI). All patients were evaluated clinically and radiographically or using computed tomography viz-a-viz dislocation, osteolysis, periprosthetic fracture, infection, loosening and implant fracture.

Results:

Three ceramic sandwich liners fracture (1.84%) were observed at an average of 7.3 years’ followup. The factors which were found to be non-significant to the ceramic liner fracture, included age (P = 0.205), weight (P = 0.241), gender (P = 0.553), BMI (P = 0.736), inclination (P = 0.199) and anteversion (P = 0.223). The overall survival was 91.4% at 12-year with revision as the endpoint. Other complications included osteolysis in 4 (2.45%), dislocation in one and periprosthetic fracture in one. In no hip aseptic loosening of the implants was seen.

Conclusions:

Our experience with the ceramic-polyethylene sandwich liner acetabular component has been disappointing because of the high rate of fracture and osteolyis. We have discontinued the use of this device and recommend the same.     

Primary cemented total hip arthroplasty: 10 years follow-up

Background:

Primary cemented total hip arthroplasty is a procedure for non-traumatic and traumatic affections of the hip. Long term follow-up is required to assess the longevity of the implant and establish the procedure. Indo-Asian literature on long term result of total hip arthroplasty is sparse. We present a 10-year follow-up of our patients of primary cemented total hip arthroplasty.

Materials and Methods:

We operated 31 hips in 30 patients with primary cemented total hip arthroplasty. We followed the cases for a minimum period of 10 years with a mean follow-up period of 12.7 years. The mean age of the patients was 60.7 years (range 37–82 yrs) male to female ratio was 2:1. The clinical diagnoses included - avascular necrosis of femoral head (n=15), sero positive rheumatoid arthritis (n=5), seronegative spondylo-arthropathy (n=4), neglected femoral neck fractures (n=3), healed tubercular arthritis (n=2) and post traumatic osteoarthritis of hip (n=2). The prostheses used were cemented Charnley’s total hip (n=12) and cemented modular prosthesis (n=19). The results were assessed according to Harris hip score and radiographs taken at yearly intervals.

Results:

The mean follow-up is 12.7 yrs (range 11-16 yrs) Results in all operated patients showed marked improvement in Harris hip score from preoperative mean 29.2 to 79.9 at 10 years or more followup. However, the non-inflammatory group showed more sustained long term improvement as compared to the inflammatory group, as revealed by the Harris hip score. Mean blood loss was 450ml (±3.7 ml), mean transfusion rate was 1.2 units (±.3). The complications were hypotension (n=7), shortening >1.5 cm (n=9), superficial infection (n=2) and malposition of prosthesis (n=1).

Conclusion:

The needs of Indian Asian patients, vary from what is discussed in literature. The pain tolerance is greater than western population and financial constraints are high. Thus revision surgery among Indian-Asian patients is less compared to western yard sticks.     

Cementless Total Hip Arthroplasty for Patients with Crowe Type III or IV Developmental Dysplasia of the Hip: Two-Stage Total Hip Arthroplasty Following Skeletal Traction after Soft Tissue Release for Irreducible Hips

Background

Total hip arthroplasty (THA) for severe developmental dysplasia of the hip (DDH) is a technically demanding procedure for arthroplasty surgeons, and it is often difficult to reduce the hip joint without soft tissue release due to severe flexion contracture. We performed two-stage THAs in irreducible hips with expected lengthening of the affected limb after THA of over 2.5 cm or with flexion contractures of greater than 30 degrees in order to place the acetabular cup in the true acetabulum and to prevent neurologic deficits associated with acute elongation of the limb. The purpose of this study is to evaluate the outcomes of cementless THA in patients with severe DDH with a special focus on the results of two-stage THA.

Methods

Retrospective clinical and radiological evaluations were done on 17 patients with Crowe type III or IV developmental DDH treated by THA. There were 14 women and 3 men with a mean age of 52.3 years. Follow-ups averaged 52 months. Six cases were treated with two-stage THA followed by surgical hip liberalization and skeletal traction for 2 weeks.

Results

The mean Harris hip score improved from 40.9 to 89.1, and mean leg length discrepancy (LLD) in 13 unilateral cases was reduced from 2.95 to 0.8 cm. In the patients who underwent two-stage surgery, no nerve palsy was observed, and the single one-stage patient with incomplete peroneal nerve palsy recovered fully 4 weeks postoperatively.

Conclusions

The short-term clinical and radiographic outcomes of primary cementless THA for patients with Crowe type III or IV DDH were encouraging. Two-stage THA followed by skeletal traction after soft tissue release could provide alternative solutions to the minimization of limb shortenings or LLD without neurologic deficits in highly selected patients.     

Bone impregnated hip screw in femoral neck fracture: Clinicoradiological results

Background:

Femoral neck fractures are treated either by internal fixation or arthroplasty. Usually, cannulated cancellous screws are used for osteosynthesis of fracture neck of femur. The bone impregnated hip screw (BIHS) is an alternative implant, where osteosyntehsis is required in femoral neck fracture.

Materials and Methods:

The BIHS is a hollow screw with thread diameter 8.3 mm, shank diameter 6.5 mm and wall thickness 2.2 mm and holes in the shaft of the screw with diameter 2 mm, placed in a staggered fashion. Biomechanical and animal experimental studies were done. Clinical study was done in two phases: Phase 1 in a group of volunteers, only with BIHS was used in a pilot study and phase 2 comparative study was done in a group with AO cannulated screws and the other group treated with BIHS.

Results:

In the phase 1 study, out of 15 patients, only one patient had delayed union. In phase 2, there were 78 patients, 44 patients in BIHS showed early union, compared to the rest 34 cases of AO cannulated screws Out of 44 patients with BIHS, 41 patients had an excellent outcome, 2 had nonunions and one implant breakage was noted.

Conclusions:

Bone impregnated hip screw has shown to provide early solid union since it incorporates the biomechanical principles and also increases the osteogenic potential and hence, found superior to conventional cannulated cancellous screw.     

Revision hip arthroplasty as a treatment of Vancouver B3 periprosthetic femoral fractures without bone grafting

Background:

It is conventionally considered that bone grafting is mandatory for Vancouver B3 periprosthetic femoral fractures (PFF) although few clinical studies have challenged the concept previously. The aim of the current study was to investigate the radiographic and functional results of Vancouver B3 PFF treated by revision total hip or hemiarthroplasty (HA) in combination with appropriate internal fixation without bone grafting.

Materials and Methods:

12 patients with Vancouver B3 PFF were treated by revision THA/HA without bone grafting between March 2004 and May 2008. There were nine females and three males, with an average age of 76 years. PFFs were following primary THA/HA in nine patients and following revision THA/HA in three. Postoperative followup was 5.5 years on average (range, 3.5-6.5 years). At the final followup, radiographic results were evaluated with Beals and Tower''s criteria and functional outcomes were evaluated using the Merle d’Aubigné scoring system.

Results:

All fractures healed within an average of 20 weeks (range, 12-28 weeks). There was no significant deformity and shortening of the affected limb and the implant was stable. The average Merle d’Aubigné score was 15.8. Walking ability was regained in 10 patients without additional assistance, while 2 patients had to use crutches. There were 2 patients with numbness of lateral thigh, possibly due to injury to the lateral femoral cutaneous nerve. There were no implant failures, dislocation and refractures.

Conclusions:

Revision THA/HA in combination with appropriate internal fixation without bone grafting is a good option for treatment of Vancouver B3 periprosthetic femoral fractures in the elderly.     

Large diameter metal on metal total hip replacement for femoral neck fractures with neurological conditions: A retrospective assessment

Background:

Patients with Parkinson''s disease and poliomyelitis can have a femoral neck fracture; yet, the optimal methods of treatment for these hips remains controversial. Many constrained or semi-constrained prostheses, using constrained liners (CLs) with a locking mechanism to capture the femoral head, were used to treat femoral neck fractures in patients with neurological disorders. We retrospectively studied a group of patients with Parkinson''s disease and poliomyelitis who sustained femoral neck fractures and were treated by total hip arthroplasty using an L-MoM prosthesis.

Materials and Methods:

We retrospectively reviewed 12 hips in 12 patients who underwent large-diameter metal-on-metal (L-MoM) total hip replacement between May 2007 and October 2009. Eight of the 12 patients (8 hips; 66.7%) had Parkinson''s disease and 4 patients (4 hips; 33.3%) were affected with poliomyelitis.

Results:

The followup time was 5.2 years (range 3.6-6.0 years). At the latest followup, all the patients showed satisfactory clinical and radiographic results, with pain relief. No complications, such as dislocation or aseptic loosening occurred.

Conclusion:

We believe the use of L-MoM can diminish the rate of instability or dislocation, after operation. The L-MoM is an option for patients with Parkinson''s disease and poliomyelitis with femoral neck fracture.     

Head size and dislocation rate in primary total hip arthroplasty

Background:

Dislocation after total hip arthroplasty (THA) has a multifactorial etiology with variables such as surgical approach, component orientation and position, type of cup, stem and head size. Review of the literature regarding the relationship of head size and dislocation rate in THA is suggestive that large femoral head size is associated with lower dislocation rate after THA. However, limited data is available as a proof of this hypothesis. The purpose of this study was to determine that the use of large head size would lead to a decreased incidence of dislocations following THA.

Materials and Methods:

317 primary THAs were performed using the posterolateral approach with posterior soft-tissue repair between January 2006 and December 2009. Cases were divided into two groups (A and B). Femoral head diameter size 36 mm was used in 163 THA in group A and 28 mm in 154 THA in group B. Average period of followup being 2 years (6 month to 4 years). Patients were routinely followed at definite intervals and were specifically assessed for dislocation.

Results:

One or more dislocations occurred in 11 out of 317 hips with the overall rate of dislocation being 3.47%. Dislocation rate was 0.6% in 36 mm head size and 6.49% with 28 mm head size (P value is 0.0107). Keeping the stem design variable as a constant, the difference in the rate of dislocation between the two groups was again found to be statistically significant for both un-cemented and cemented stem.

Conclusion:

Dislocation rate decreased significantly as the size of the head increased in primary THA. However, longer followup is necessary as rate of dislocation or in vivo highly cross linked poly failure or fracture may increase in future affecting the rate of dislocations in primary THA.