15-year experience with tapered fluted modular titanium stems in revision hip arthroplasty and complex femoral reconstruction: a long-term survivorship analysis in a tertiary care centre

Abstract

Introduction:

Over the past 2decades, tapered fluted modular titanium stems have gained wide acceptance due to their intraoperative versatility and encouraging early- to mid-term outcomes. This study aims to analyse the clinical and radiographic outcomes, complications, and survivorship of tapered fluted modular titanium stems in revision THA and complex femoral reconstruction with long-term follow-up.

Materials and methods:

A retrospective study was conducted on patients who underwent revision hip surgery or complex reconstruction using a non-cemented modular tapered fluted stem at a single institution between 2009 and 2016. A total of 47 patients (48 hips) were included. Clinical evaluation was performed using the Harris Hip Score (HHS). Radiographic parameters were used to assess implant stability, osteointegration, subsidence, and stress shielding. Complications were recorded, and implant survivorship was analysed using the Kaplan-Meier method.

Results:

The mean age was 70 (range 37–95) years, with a mean follow-up of 9 (range 6–15) years. All patients showed functional and pain improvement after surgery, with an average increase of 38 points in the HHS (p < 0.001). Distal osteointegration was observed in 96% of cases, with a significant subsidence rate (>5 mm) of 4%. Stress shielding was present in 8% of cases. A total of 6 reoperations were recorded: 3 (6%) due to recurrent dislocation, 2 (4%) due to septic loosening, and 1 (2%) due to aseptic loosening. Overall implant survivorship was 87.5% for any reoperation, 91.7% for any stem revision, and 100% for stem revision due to mechanical failure of the femoral component.

Conclusions:

The modular tapered fluted stem proved to be a reliable and durable option in revision total hip arthroplasty and complex femoral reconstruction, with high rates of osteointegration and long-term stability. Its design allows for effective distal fixation and bone reconstruction in patients with severe femoral defects.

Keywords

Fluted modular stem revision hip arthoplasty tapered

Introduction

Revision total hip arthroplasty (THA) and the management of complex femoral defects where the native metaphyseal bone stock is insufficient for reliable fixation represent some of the most demanding procedures in adult reconstructive surgery.¹ The increasing longevity of the population and the rising number of primary THAs have led to a growth in revision procedures, many of which are performed in the setting of substantial femoral bone loss.² In these cases, achieving durable fixation and restoring limb biomechanics are major challenges, particularly when metaphyseal support is compromised.³

Tapered fluted modular titanium (TFMT) stems were developed to address these difficulties by providing consistent diaphyseal distal fixation, controlled load transfer, and intraoperative versatility in version, offset, and leg length restoration.⁴ Given the increasing use of TFMT stems for periprosthetic fractures, infection-related bone loss, and severe femoral defects, there is a need for studies reporting long-term stability, osteointegration, and mechanical performance.

Therefore, the aim of this study is to evaluate the long-term clinical, radiographic, and survivorship outcomes of a TFMT stem in revision THA and complex femoral reconstruction performed at a high-volume tertiary hospital.

Materials and methods

After obtaining approval from the institutional ethics committee, the medical records of all patients who underwent revision hip arthroplasty or complex femoral reconstruction at our hospital between 2009 and 2016 were reviewed. Only patients who received an uncemented distally fixed TFMT stem were included.

The indication for a TFMT stem was determined by the presence of femoral conditions in which metaphyseal support was inadequate and distal fixation was required. These included: (1) loss of proximal bone stock due to aseptic or septic loosening; (2) periprosthetic fractures with instability of the existing stem or compromised metaphyseal bone; (3) chronic infection resulting in bone defects; (4) failed fixation devices or failed primary implants requiring femoral reconstruction; and (5) complex deformities or dysplastic anatomy preventing reliable metaphyseal fixation. In these settings, modularity allowed controlled restoration of version, limb length, and offset once a stable diaphyseal anchorage had been achieved.

During the same study period, other revision strategies such as cemented stems, proximally fixed stems, or cylindrical stems were also used in selected patients at our institution. These implants were typically chosen when adequate metaphyseal support was preserved, in low-demand patients, or in cases where anatomy or bone quality allowed for secure proximal fixation. Thus, differences in stem selection reflected the underlying defect pattern and surgical indication.

The present study was deliberately restricted to the subgroup treated with a tapered fluted modular stem, in order to provide a homogeneous analysis of a single distal fixation philosophy. Patients < 18 years and those with < 6 years of postoperative follow-up were also excluded.

A total of 60 patients (61 hips) underwent revision surgery or complex reconstruction with implantation of a non-cemented TFMT distal fixation stem during the study period. Of the 60 patients (61 hips) initially treated with a TFMT stem during this period, 13 were excluded from the final analysis. 11 patients (11 hips) died before reaching the minimum 6-year follow-up, none due to causes related to the femoral reconstruction. 2 patients (2 hips) were lost to follow-up (1 voluntary discharge and 1 transfer to another region). Therefore, 47 patients (48 hips) met the inclusion criteria and were analysed (Figure 1).

The mean follow-up period was 9 years (range 6–15 years). 14 patients (30%) were male and 33 (70%) were female. The mean age at the time of hip surgery was 70 years (range 37–96 years). The indications for the use of the stem in these patients are presented in Table 1.

Table 1.

Indications for placement of the tapered fluted modular titanium stem MP (Link).

Indication for surgery	No. of hips (%)
Aseptic loosening	3 (6%)
Septic loosening	13 (27%)
Periprosthetic joint infection (PJI)	12 (25%)^a
Periprosthetic fracture (Vancouver B1–B3)	6 (13%)
Failure of internal fixation devices (nail cut-out, cut-in, non-union)	5 (11%)
Femoral reconstruction in primary arthroplasty	3 (6%)
Femoral reconstruction in dysplastic hip anatomy	2 (4%)
Femoral reconstruction in tumoural pathology	2 (4%)
Failed hip arthrodesis	1 (2%)
Recurrent dislocation of THA requiring femoral revision	1 (2%)

PJI category includes both early and late infections without loosening that required femoral reconstruction and component revision. These patients were treated according to institutional PJI protocols, using either a 1-stage or a 2-stage exchange depending on chronicity, pathogen virulence, soft-tissue condition, and host status.

7 patients underwent femoral reconstruction in the context of primary arthroplasty. 4 cases corresponded to severe dysplastic hip anatomy or tumoral pathology in which the proximal femur provided insufficient metaphyseal support. In 3 additional cases performed for primary osteoarthritis, proximal morphology or bone quality did not allow reliable metaphyseal fixation due to deformity, cavitary defects, or compromised trabecular support. In all 7 cases, a tapered fluted modular stem was selected to achieve secure diaphyseal fixation and restore offset, version, and limb length. Although these procedures were technically primary arthroplasties, the reconstructive principles and fixation strategy were identical to those of femoral revision surgery; therefore, they were included in the analysis as femoral reconstruction cases.

Surgical technique

The procedure was performed by 1 of 2 senior surgeons. Preoperative planning was essential, involving detailed radiographic analysis to assess the extent of bone loss and to select appropriate modular components of the system. In all cases, a posterolateral approach was used to ensure proper exposure of both the proximal femur and acetabulum. Prosthesis extractors were used while attempting to preserve as much acetabular and femoral bone stock as possible. A thorough debridement of the femoral canal was then performed using high-speed burrs to remove cement and granulation tissue.

When a broader exposure was necessary for complex acetabular reconstructions or for the removal of a well-fixed femoral stem, an extended trochanteric osteotomy (ETO) was performed. This procedure was done in 26 hips (54%). Following reduction, the ETO site was stabilised with cerclage cables, optionally combined with a grip plate.

The acetabular component was revised in 34 hips (71%). Any cemented or newformed material was removed using hemispherical reamers until bleeding, stable bone was achieved. In 7 cases (15%), there was significant bone loss; of these, 5 (11%) required structural bone allografts, and 2 (4%) required reconstruction with a metal reinforcement ring (Partial Pelvis Replacement, LINK).

The Link MP modular stem (Waldemar Link, Hamburg, Germany) without hydroxyapatite coating was used in all hips. This is a TFMT uncemented titanium stem designed for distal fixation. The modular design of the MP prosthesis allows the combination of various components, giving the surgeon great flexibility to adjust leg length, femoral offset, and anteversion independently of distal fixation. The femoral cone has a 2° taper and 3° curvature. The stem size was selected according to the canal diameter, followed by selection of length segments and neck options, which can be adjusted in various angles to correct leg length discrepancies or enhance joint stability. Modular spacers of 10 mm length are also available and were used in 2 patients (4%) in our cohort.⁵

The TFMT stem was always implanted in a sequential fashion. First, the distal fluted tapered segment was inserted alone and impacted until achieving rotational and axial stability, as specified in the surgical technique of this implant. Once secure diaphyseal fixation was confirmed, the proximal body was attached to the distal segment using the modular junction. Modularity allowed fine adjustment of version, offset, and leg length after stable distal anchorage had been obtained. This technique ensures optimal biomechanical reconstruction and avoids the risks associated with inserting a fully assembled implant.

In all cases, a press-fit fixation was achieved. After insertion of both the femoral and acetabular components, hip reduction was performed. The hip was moved through its full range of motion to verify stability and mobility. At this stage, leg length and femoral axis alignment were also verified. Modular components could be adjusted if necessary to optimise biomechanics and functionality.

Cerclage wiring was required in 29 patients (60%), and in 10 of them (21%) an additional plate (ACCORD Cable System, Smith & Nephew, Memphis, TN, USA) was also placed. Bone allografts were additionally used in 5 patients (10%) due to major bone defects around the proximal component.

Haemostasis was carefully performed, and closure was carried out in anatomical layers, with special attention to the proper repair of the abductor musculature to ensure adequate postoperative stability. A drain was placed in all hips, and subcutaneous tissue was closed with absorbable sutures, while the skin was closed with staples.

Rehabilitation began within 24–48 hours postoperatively in all patients, following an early mobilisation protocol developed by our hospital’s Rehabilitation Department. Except for 7 patients (13%) in which initial fixation was not strong enough, all others were allowed immediate full weight-bearing with the help of crutches or a walker. All patients were advised on precautions to avoid dislocation.

Clinical and radiological evaluation

During hospitalisation, each patient was evaluated for anaesthetic risk using the ASA classification, postoperative transfusion requirements, intra- and postoperative complications, time to ambulation, and total length of stay.

Post-discharge follow-up was conducted in outpatient orthopedic clinics by the operating surgeon at 1, 3, and 6 months, at 1 year, and annually thereafter. At each visit, clinical and radiographic data were collected. Clinical evaluation was performed using the Harris Hip Score (HHS), which was compared with the preoperative score. Radiographic evaluation was standardised for all patients. In patients presenting with periprosthetic fractures, the preoperative HHS corresponded to the last routine follow-up visit prior to the fracture event. All patients undergoing THA are clinically evaluated in our institution, which allowed the use of validated pre-fracture functional scores rather than measurements influenced by the acute injury.

At each follow-up visit, an anteroposterior (AP) radiograph including the pelvis, hip, and entire femur, as well as a lateral radiograph of the hip and femur, were obtained and compared with the immediate postoperative images to identify changes. This protocol allowed full visualisation of the entire femoral stem. Bone loss in hips without fracture, distal osteointegration, stem subsidence, and stress shielding were assessed. Bone loss was classified according to Paprosky classification.⁶ Osteointegration was evaluated using the criteria of Rodríguez et al.⁷, a modification of Engh et al.’s method tailored to TFMT stems.⁸ Stem migration was assessed by measuring vertical subsidence of the femoral stem following the method of Hannon et al.⁹, with subsidence ⩾ 5 mm considered significant. Stress shielding was defined as an area of decreased bone density around the stem.

Statistical analysis

Quantitative variables were presented as means and ranges. The Shapiro–Wilk test was used to assess the normality of distributions. Qualitative variables were expressed as absolute numbers (case count) and relative frequencies (percentage).

Overall stem survivorship (in years) was estimated using the Kaplan–Meier method. The log-rank test was used to compare survival curves. A Cox regression analysis was performed for each major factor related to implant failure for any cause.

All statistical analyses were performed using Stata for Windows, version 16 (StataCorp. 2019. Stata Statistical Software: Release 16. College Station, TX: StataCorp LLC.). A 5% alpha level (2-tailed) was considered statistically significant. Because this was a retrospective observational study with a fixed sample determined by institutional caseload, no a priori power analysis was performed.

Results

Clinical results

Regarding surgical risk, 5 patients (11%) were ASA I, 9 (19%) ASA II, 29 (62%) ASA III, and 4 (8%) ASA IV. Postoperative blood transfusions were required in 26 patients (55%), with a mean of 3 units of red blood cells concentrated per patient (range 1–13). 2 patients received 2 units intraoperatively.

All patients experienced clinical and functional improvement in terms of pain and mobility after surgery. At final follow-up, the average HHS improved from 43 (range 14–86) preoperatively to 81 (range 61–98). This represents a mean increase of 38 points (95% CI, 29–47; p < 0.001). At the last follow-up visit, 17 patients (37%) walked unaided, 20 (43%) used a cane, 2 (4%) used 1 crutch, 4 (8%) used 2 crutches, and 4 (8%) used a walker. The average limb-length discrepancy was 8 mm longer on the revised side (range 0–24 mm). The mean time to ambulation was 7 days (range 2–42 days), and the average length of postoperative hospital stay was 17 days (range 5–73 days) (Table 2).

Table 2.

Clinical outcomes.

Category	Outcomes
ASA Risk
— ASA I	5 (11%)
— ASA II	9 (19%)
— ASA III	29 (62%)
— ASA IV	4 (8%)
Blood transfusion
— Intraoperative	2 (4%)
— Postoperative	26 (55%)
— Mean of red blood cells concentrates	3 per patient (range 1–13)
Mean time to ambulation	7 days (range 2–42)
Walking aids
— Unaided	17 (37%)
— Cane	20 (43%)
— One crutch	2 (4%)
— 2 crutches	4 (8%)
— Walker	4 (8%)
Mean postoperative length of stay	17 days (range 5–73)
Harris Hip Score
— Preoperative	43 (range 14–86)
— Postoperative	81 (range 61–98)
Lower limb-length discrepancy	>8 mm in revised side (range 0–24 mm)

Radiological results

Among the 6 hips with periprosthetic fractures, 2 (33%) were classified as Vancouver type B1, 3 (50%) as type B2, and 1 (17%) as type B3. Both cases of Vancouver type B1 periprosthetic fractures were fracture-dislocations with instability after reduction, which is why stems were revised. Of the remaining 42 hips, 4 (8%) were classified as Paprosky type II, 23 (48%) as type IIIA, 9 (19%) as type IIIB, and 6 (13%) as type IV.

Distal segment osteointegration was observed in 46 hips (96%). Subsidence greater than 5 mm was documented in 2 hips (8 mm and 12 mm; mean 10 mm), representing a 4% subsidence rate (p < 0.001). In both cases, subsidence was identified within the first 3-month follow-up and remained stable throughout the remainder of the follow-up period.

Stress shielding was identified in 3 hips (6%) at the metaphyseal level and in 1 hip (2%) at the diaphyseal level, accounting for a total of 8% of cases with stress shielding in our sample. All patients with either subsidence or stress shielding remained asymptomatic during follow-up (Table 3).

Table 3.

Radiological outcomes.

Category	Outcomes
Vancouver classification for fractured hips (n = 6)
— Type B1	2 (4%)
— Type B2	3 (6%)
— Type B3	1 (2%)
Paprosky classification for non-fractured hips (n = 42)
1. Type II	4 (8%)
2. Type IIIA	23 (48%)
3. Type IIIB	9 (19%)
4. Type IV	6 (13%)
Distal osteointegration	46 (96%)
Subsidence (>5 mm)	2 (4%) p<0,001
Stress-shielding
— Metaphyseal	3 (6%)
— Diaphyseal	1 (2%)

When hips were grouped according to the presence of a preserved femoral isthmus, 27 hips were classified as Paprosky II–IIIA and 15 as IIIB–IV. Distal osteointegration occurred in 27/27 hips (100%) in the II–IIIA group and in 14/15 hips (93.3%) in the IIIB–IV group (p = 0.530). Clinically relevant subsidence (> 5 mm) was observed in 2/27 hips (7.4%) vs. 0/15 hips (0%), respectively (p = 0.357). Stress shielding occurred in 1/27 hips (3.7%) and in 1/15 hips (6.7%) (p = 0.840). No statistically significant differences were found for any of the radiographic endpoints, and no mechanical stem failures occurred in either subgroup.

Complications and reoperations

The complications are summarised in Table 4. Intraoperatively, there were 3 cases (6%) of periprosthetic fractures (2 type B1 and 1 type AG according to the Vancouver classification) during removal of the previous implant, and 4 cases (8%) of fracture (2 type B1 and 2 type C) during insertion of the new stem (Figure 2). The 2 type C fractures required osteosynthesis with VA LCP plate and cerclage wires. The remaining fractures were managed with cerclage and reimplantation of the same stem. All of them showed satisfactory postoperative outcomes without the need for further surgery. No other intraoperative complications were observed.

Table 4.

Intraoperative and postoperative complications.

Category	Outcomes
Intraoperative complications — Fracture during removal of previous implant (n = 3)○ Vancouver type AG○ Vancouver type B1— Fracture during introduction of TFMT stem (n = 4)○ Vancouver type B1○ Vancouver type C	1 (2%)2 (4%)2 (4%)2 (4%)
Postoperative complications— Isolated dislocation— Recurrent dislocations— Periprosthetic fracture (Vancouver type B1)— Late infection of the prosthesis— Aseptic loosening of acetabular component	1 (2%)3 (6%)1 (2%)5 (10%)1 (2%)

TFMT, tapered fluted modular titanium.

Note: 2 cases resulted in septic loosening of the stem.

The fractures occurred during distal preparation or controlled impaction of the diaphyseal component, a complication profile consistent with previously reported rates for diaphyseal-engaging revision stems. None of the intraoperative fractures were related to the insertion of a fully assembled modular stem. As our experience evolved, we incorporated distal cerclage wiring to minimise the risk of intraoperative fracture.

During the postoperative period, there were 4 cases of dislocation: one isolated and 3 recurrent. The isolated dislocation was successfully managed with closed reduction and did not recur. Among the recurrent dislocations, 1 hip required acetabular revision, with good clinical evolution. In another case, the metaphyseal component, the acetabular cup, and the polyethylene liner were revised, also with favourable outcome. In the third case, due to significant knee instability, a total femur prosthesis was implanted. This total femur later developed a chronic infection caused by Enterococcus faecalis, requiring long-term suppressive treatment with amoxicillin. At present, the patient ambulates with 1 crutch and remains pain-free.

We had 1 case of a Vancouver type B1 periprosthetic fracture one week after surgery. The patient remained non-weight bearing for 6 weeks and later began partial weight-bearing, without further complications.

In addition to the total femur infection previously described, there were 4 other cases (8%) of late implant infection (3 caused by Staphylococcus epidermidis and 1 by S. aureus), of which 2 (4%) resulted in septic loosening. 1 of the loosened implants was treated with a 2-stage revision of both the acetabular and femoral components. This patient subsequently developed a greater trochanteric nonunion, which has remained asymptomatic and free of complications to date. In the other patient, due to bone stock loss after removal of the infected implant, a 2-stage reconstruction with a megaprosthesis (Ag-coated MegaSystem C, Link) was performed. In the cases of infection without loosening, surgical treatment was ruled out due to hip ankylosis and the patients’ poor baseline condition; intravenous antibiotic therapy was initiated instead, resulting in full clinical recovery in both patients.

We observed 1 case of aseptic loosening of the acetabular component 3 years after surgery, which was treated with isolated acetabular revision; the femoral component remained unchanged. There were no cases of femoral component aseptic loosening or implant fracture. Therefore, there was not observed any case of mechanical failure of this stem.

Implant survivorship

A total of 6 reoperations were performed: 3 due to recurrent dislocations, 2 due to septic loosening, and 1 due to aseptic loosening of the acetabular component. Kaplan-Meier cumulative survivorship was 87.5% for reoperation for any reason; 91.7% for stem revision for any reason; and 100% for stem revision due to mechanical failure of the femoral component (Figures 3 –5).

Discussion

Revision THA is increasingly needed for aseptic loosening, infection, and periprosthetic fractures, often complicated by femoral bone loss. TMFT stems offer dependable distal fixation and allow intraoperative adjustment of limb length, offset, and neck version to restore stability and function. Although the cohort includes a spectrum of complex femoral reconstruction scenarios, the indication for the TFMT stem was consistent across all cases: reliable diaphyseal fixation when proximal bone stock was inadequate for metaphyseal anchorage. This reflects real-world practice in a tertiary referral center and justifies analysing these cases under a unified reconstructive philosophy.

The cumulative survival rate of the femoral stem in our series was 100% when considering revision for mechanical failure, and 91.7% when including any stem-related cause. Several studies have reported similar implant survival rates. Park et al.¹⁰ reported 94.6% survivorship free from aseptic loosening at a mean follow-up of 16 years, while Rodríguez et al.⁷ reported 98.4% survivorship free from mechanical failure in a cohort with up to 15 years of follow-up. Van Houwelingen et al.¹¹ also reported high survivorship in patients with severe bone defects (Paprosky types IIIB and IV). Our results, which include a high proportion of Paprosky IIIA, IIIB, and IV defects (79% of all hips) and only one case of mechanical stem failure, confirm those reported in that study, with even higher survivorship rates, suggesting that the implant used provides reliable fixation even in complex scenarios.

Femoral stem osteointegration is a key parameter in assessing long-term stability in revision THA and complex femoral reconstruction. In our cohort, the radiographic distal segment osteointegration rate was 96%. Rodríguez et al.⁷, focusing specifically on osteointegration and bone remodelling patterns, documented 100% distal osteointegration in a cohort of 64 tapered fluted modular stems, with “spot weld” bone formations observed in all implants, predominantly in the distal segment, indicating robust and durable fixation. Park et al.¹⁰ also reported very high osteointegration rates, with no cases of aseptic loosening of the femoral component. Although specific rates were not reported, the 94.6% implant survival and absence of loosening imply long-term effective bone integration. Overall, the reviewed literature consistently shows radiographic osteointegration rates between 96% and 100% with modular stems, provided reliable distal anchorage and proper surgical technique are ensured.^10
–12

Stem subsidence following revision surgery is a relevant complication in terms of primary mechanical stability and potential implant failure. In our series, clinically significant subsidence (>5 mm) occurred in only 4% of cases, and in all of them was early and stable, without further radiographic progression or clinical impact. These findings are consistent with recent literature, which reports subsidence rates between 5% and 26%, and suggests that mild, early, and non-progressive subsidence may represent physiological implant settling rather than impending failure.^10,12

Subsidence rates are variably reported in the literature and tend to be lower with modular stems than with monoblock designs. Böhm and Bischel,¹³ evaluating the monoblock Wagner SL revision stem, reported >10 mm subsidence in 20% of cases, most of which stabilised. In this study, subsidence was associated with undersized stems, suboptimal canal preparation, or intraoperative fractures.¹³ Similarly, Gutiérrez del Álamo et al.¹⁴ reported a 19% subsidence rate (>10 mm) with the same design, identifying canal fill as the most important predictor of successful osteointegration, as poor canal-stem contact led to higher risk of subsidence.

Other studies show variable rates: Köster et al.¹⁵, in a study where 73 patients were evaluated with only 2 cases of subsidence, did not report specific figures but emphasised the importance of adequate cortical contact, while Park et al.¹⁶ confirmed that most minor subsidence cases stabilised without affecting implant survival. This last author reported 3 cases of subsidence out of 59 patients studied, among which 1 case was due to a dissociation of the coupling component, and the other 2 were linked to nonunion at the osteotomy site of the proximal component.¹⁶

Stress shielding is a form of bone atrophy caused by load transfer to the stem and reduced mechanical stimulation in the proximal bone. Although often asymptomatic, it may affect bone quality in future revisions.¹⁶ In our cohort, stress shielding was observed in 8% of hips, a low and clinically irrelevant rate, as no patients experienced pain or functional impairment. This is notably lower than many reference studies, which report incidences of 16–29%.^16,17

The low incidence of stress shielding observed in our cohort (8%) can be ascribed chiefly to biomechanical and surgical factors intrinsic to the series. The tapered-fluted Link MP stem, manufactured from titanium (elastic modulus ≈ 110 GPa), transfers load more physiologically than cobalt-chromium cylindrical stems (> 200 GPa). Its 2° taper and longitudinal flutes favour short diaphyseal fixation and a graded distribution of stresses, design characteristics that have consistently been shown to lessen proximal cortical atrophy when compared with fully porous cylindrical stems.^18,19 Moreover, in about 60% of cases an extended trochanteric osteotomy and/or structural grafting was performed, techniques that restore proximal bone stock and provide an additional load-sharing buttress.²⁰

In a study by Richards et al.¹⁹, comparing tapered fluted modular titanium stems to non-modular cobalt-chrome cylindrical stems (CNCC) with cementless femoral fixation, the titanium group had significantly lower stress shielding (8% vs. 28%), attributed to titanium’s lower elastic modulus, which improves load transmission to the proximal bone. Böhm and Bischel¹³ did not report shielding rates but found excellent proximal remodeling in 88% and complete bone restoration in 70% of cases. These results suggest that even without proximal modularity, diaphyseal fixation with a tapered geometry can induce favourable adaptive bone responses.

Subgroup analysis according to femoral defect severity did not reveal clinically relevant or statistically significant differences. Hips with a preserved femoral isthmus (Paprosky II–IIIA) showed radiological outcomes comparable to those with more extensive defects (IIIB–IV), with no significant differences for osteointegration (p = 0.530), subsidence (p = 0.357), or stress shielding (p = 0.840). These findings support the ability of tapered fluted modular stems to achieve stable distal fixation regardless of proximal defect severity, provided adequate distal canal fill is obtained.

Clinically, the HHS improved significantly (mean increase of 38 points), consistent with Ovesen et al.¹⁸ and Park et al.¹⁶, who reported gains of 37–40 points in similar cohorts. In a more demanding setting, Van Houwelingen et al.¹¹ showed HHS improvement from 36 to 78 (mean 42 points). Although the final score was slightly lower, this may reflect the severity of the defects treated, highlighting the functional gains achieved.

Regarding complications, we observed a dislocation rate of 12%, consistent with other series.^10,20 Infection remains a leading cause of implant failure (8% in our series), similar to published rates.^7,12 Lakstein et al.²¹ identified specific risk factors for modular stem fracture, such as high body mass index (BMI), poor proximal bone support, and use of small-diameter stems.

1 longstanding concern with modular stems is the risk of fracture at the modular junction. In our series, no implant fractures occurred. However, studies by Van Houwelingen et al.¹¹ and Park et al.¹⁰ reported up to 5% fracture rates with earlier-generation designs. Lakstein et al.²¹ described ZMR stem fractures due to flexural fatigue and fretting corrosion at the junction in cases with poor proximal support. ZMR implant consists of a modular hip system offering tapered, porous, and splined stems. This design was associated with a high risk of mechanical failure, particularly in the taper body, which was withdrawn after a Zimmer safety alert. The modular junction initially had a 14 mm diameter, later reinforced to 19.5 mm in the XL version to reduce fracture risk.²¹

The exceptionally low rate of mechanical failure observed in our series, 97.9% stem survivorship with no implant fractures, could be explained by the design of the Link MP tapered-fluted stem. This stem is forged from titanium alloy, whose high fatigue strength and lower elastic modulus reduce stress concentrations along the modular junctions.⁵ The 2° taper, substantial core diameter, and deep longitudinal flutes distribute loads more evenly than early cylindrical cobalt-chromium designs, in which junction fractures were reported as stated previously.^5,21 By eliminating narrow “waist” regions and relying on a high-angle Morse taper, the stem resists cyclic bending and torsional fatigue that historically precipitated breakage.

In summary, the literature identifies the most common complications as dislocation (5–21%),^22
–25 infection (5–15%),^2,26
–28 periprosthetic fracture (3–12%),^29
–32 and less frequently, implant fracture. Despite these issues, most series report long-term survivorship rates above 90%, confirming that with proper technique, modular tapered fluted stems offer an acceptable safety profile.

1 of the main limitations of this study is its retrospective and observational design, which may introduce selection and information bias. The absence of a control group (e.g., patients treated with other stem types) limits our ability to directly attribute outcomes to the implant design. Furthermore, the heterogeneity in indications and bone defects may affect consistency of clinical and radiographic outcomes. Another limitation is that stem migration was assessed using conventional radiographs rather than Einzel-Bild-Röntgen-Analyse (EBRA) or radiostereometric analysis (RSA), which offer greater measurement precision. These advanced methods were not routinely available at our institution during the early years of the study period. Nevertheless, our standardised protocol, obtaining full-length anteroposterior and lateral femoral radiographs at every follow-up visit, is consistent with the methodology used in previous studies of tapered fluted modular stems, allowing meaningful comparison with the existing literature. Despite these limitations, the study provides long-term real-world outcomes for a tapered fluted modular stem in a challenging population.

Conclusion

TFMT stems demonstrate reliable distal fixation, intraoperative adaptability of leg length, offset, and version, and high long-term survivorship with predictable osseointegration and functional recovery in revision total hip arthroplasty and complex femoral reconstruction, even with substantial proximal bone loss. However, concerns persist regarding intraoperative fractures and mechanical failure at the modular junction, underscoring the importance of meticulous surgical technique and appropriate patient selection.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

José Antonio Guerrero-Serrano

Claudia Ortega-Romero

José María García-López

References

Learmonth

Young

Rorabeck

The operation of the century: total hip replacement. Lancet 2007; 370: 1508–1519.

Bozic

Kurtz

Lau

, et al. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am 2009; 91: 128–133.

Wagner

. A revision prosthesis for the hip joint. Orthopade 1989;18: 438–453.

Kuruvalli

Manggat

Maheson

, et al. Intraoperative fractures in modular and nonmodular tapered stems in revision THA: a comparative study. Hip Int 2021; 31: 307–312.

Waldemar Link. MP Reconstruction Prosthesis – modular hip revision stem [Internet]. Hamburg: Waldemar Link GmbH & Co. KG, https://www.medicalexpo.es/prod/waldemar-link/product-110890-1020076.html (accessed 12 April 2025).

Paprosky

Perona

Lawrence

JM.

Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. J Arthroplasty 1994; 9: 33–44

Rodriguez

Deshmukh

Robinson

, et al. Reproducible fixation with a tapered, fluted, modular, titanium stem in revision hip arthroplasty at 8–15 years follow-up. J Arthroplasty 2014; 29(Suppl.): 214–218.

Engh

Massin

Suthers

KE.

Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop Relat Res 1990; (257): 107–128.

Hannon

Sheehan

Duong

, et al. Modular fluted tapered stems for periprosthetic femoral fractures: excellent results in 171 cases. J Bone Joint Surg Am 2022; 104: 1188–1196.

10.

Park

Lee

Shin

, et al. Long-term outcomes of revision total hip arthroplasty using a tapered and fluted modular stem: a mean follow-up of 16 years. J Arthroplasty 2022; 37: 2420–2426.

11.

Van Houwelingen

Duncan

Masri

, et al. High survival of modular tapered stems for proximal femoral bone defects at 5 to 10 years follow-up. Clin Orthop Relat Res 2013; 471: 454–462.

12.

Brown

Tetreault

Cipriano

, et al. Modular tapered implants for severe femoral bone loss in THA: reliable osseointegration but frequent complications. Clin Orthop Relat Res 2015; 473: 555–560.

13.

Böhm

Bischel

. Femoral revision with the Wagner SL Revision Stem: evaluation of one hundred and twenty-nine revisions followed for a mean of 4.8 years. J Bone Joint Surg Am 2001; 83: 1023–1031.

14.

Gutiérrez del Alamo

Garcia-Cimbrelo

Castellanos

, et al. Radiographic bone regeneration and clinical outcome with the Wagner SL Revision Stem. J Arthroplasty 2007; 22: 515–523.

15.

Köster

Walde

Willert

HG.

Five- to 10-year results using a noncemented modular revision stem without bone grafting. J Arthroplasty 2008; 23: 964–972.

16.

Park

Lee

Park

, et al. A distal fluted, proximal modular femoral prosthesis in revision hip arthroplasty. J Arthroplasty 2010; 25: 932–938.

17.

Rodriguez

Deshmukh

Rasquinha

, et al. Patterns of osseointegration and remodeling in femoral revision with bone loss using modular, tapered, fluted, titanium stems. J Arthroplasty 2011; 26: 1409–1417.e1.

18.

Ovesen

Emmeluth

Hofbauer

, et al. Revision total hip arthroplasty using a modular tapered stem with distal fixation: good short-term results in 125 revisions. J Arthroplasty 2010; 25: 348–354.

19.

Richards

Duncan

Masri

, et al. Femoral revision hip arthroplasty: a comparison of two stem designs. Clin Orthop Relat Res 2010; 468: 491–496.

20.

Feng

Zhang

Wang

, et al. Comparison of modular and non-modular tapered fluted titanium stems in femoral revision hip arthroplasty. Sci Rep 2020; 10: 13692.

21.

Park

Moon

Lim

SJ.

Revision THA using a fluted and tapered modular distal fixation stem with and without extended trochanteric osteotomy. J Arthroplasty 2007; 22: 993–999.

22.

Lakstein

Eliaz

Levi

, et al. Fracture of cementless femoral stems at the mid-stem junction in modular revision hip arthroplasty systems. J Bone Joint Surg Am 2011; 93: 57–65.

23.

Berend

Lombardi

Jr Mallory

, et al. Cementless femoral revision arthroplasty with distal fixation: 9- to 15-year follow-up. Clin Orthop Relat Res 2006; (453): 230–234.

24.

Patel

Potts

Froehlich

JA.

The dislocation rate of primary total hip arthroplasty is underestimated in clinical studies: a systematic review. Hip Int 2020; 30: 5–15.

25.

Alberton

High

Morrey

BF.

Dislocation after revision total hip arthroplasty: an analysis of risk factors and treatment options. J Bone Joint Surg Am 2002; 84: 1788–1792.

26.

Springer

Fehring

Griffin

, et al. Why revision total hip arthroplasty fails. Clin Orthop Relat Res 2009; 467: 166–173.

27.

Kunutsor

Whitehouse

Blom

, et al. Re-infection outcomes following one- and two-stage surgical revision of infected hip prosthesis: a systematic review and meta-analysis. PLoS One 2015; 10: e0139166.

28.

Zmistowski

Karam

Durinka

, et al. Periprosthetic joint infection increases the risk of one-year mortality. J Bone Joint Surg Am 2013; 95: 2177–2184.

29.

Lora-Tamayo

Murillo

Iribarren

, et al. A large multicenter study of methicillin-susceptible and methicillin-resistant Staphylococcus aureus prosthetic joint infections managed with implant retention. Clin Infect Dis 2013; 56: 182–194.

30.

Abdel

Cottino

Mabry

, et al. Management of periprosthetic femoral fractures following total hip arthroplasty: a review. Int Orthop 2015; 39: 2005–2010.

31.

Lindahl

Epidemiology of periprosthetic femur fracture around a total hip arthroplasty. Injury 2007; 38: 651–654.

32.

Bhattacharyya

Chang

Meigs

, et al. Mortality after periprosthetic fracture of the femur. J Bone Joint Surg Am 2007; 89: 2658–2662.