Results

Literature search

The search strategy yielded 127 potentially relevant studies, of which seven studies met the inclusion criteria for detailed analysis. Primary data were derived from the cohorts reported by Tyler et al. [11], Healey et al. [12], Tanaka et al. [22], Goldman et al. [23], Corona et al. [24], Monument et al. [25], and Kagan et al. [26]. Across these seven cohorts, 455 cases were tumor-related/oncologic and 109 were non-oncologic, based on the indication categories reported in the original studies.

Methodological quality of the included studies

Overall, the included studies demonstrated moderate methodological quality. Common limitations included retrospective study design, lack of prospective sample size calculation, absence of blinded endpoint assessment, and limited availability of appropriate control groups. These methodological constraints should be considered when interpreting the reported fracture rates, survivorship outcomes, and risk factor analyses.

Incidence of periprosthetic fractures

The total number of periprosthetic fractures or aseptic mechanical failures related to the CPS device was generally low across studies (Table 2). Tyler et al. [11] conducted a large multicenter cohort study of 221 patients and reported a periprosthetic fracture rate of 2.7% (n = 6); among distal femoral implants, the rate was 3.9% (6/154). The reported fracture rate appears low in absolute terms. However, direct comparison with the cumulative risk of aseptic loosening reported for cemented megaprostheses should be interpreted cautiously because follow-up durations and failure endpoints differ among studies [27, 28] (Table 1). Monument et al. [25] reported one periprosthetic fracture (4.5%) in a femoral oncologic cohort of 22 patients, whereas Kagan et al. [26] reported an overall failure rate of 22%, with aseptic mechanical failure accounting for 5.3% (n = 6) of 114 cases. Goldman et al. [23] reported a 9% aseptic mechanical failure rate, with no additional aseptic mechanical failures after 2 years.

Study | N | Population | Follow-up (months) | Periprosthetic fracture/mechanical rate | Key findings
Tyler et al. (2009) [11] | 221 | Adult patients with compressive osseointegration reconstruction, including primary oncology 165, revision oncology 33, revision arthroplasty 18, and post-traumatic 5 | 53 (mean) | 2.7% (n = 6) | All fractures occurred within 2 years, and the bone-implant interface remained stable in all fracture cases.
Healey et al. (2013) [12] | 82 | Adult patients undergoing Compress knee arthroplasty, including tumor reconstruction 80 and noncancer revision TKA 2 | 60 (median) | Approximately 3% | Ten-year all-cause survivorship was 80%, with high interface stability and minimal aseptic loosening.
Tanaka et al. (2023) [22] | 36 | Pediatric oncologic patients, including osteosarcoma 34 and Ewing sarcoma 2 | 87.4 (mean) | 18% (n = 6) | Spindle survivorship was 86.3% at 5 years and 66.2% at 10 years, and the complication rate was relatively high because of expandable components.
Goldman et al. (2016) [23] | 79 | Adult distal femur oncologic reconstruction cases | 60 (mean) | 9% (aseptic mechanical failure) | Spindle survival free from mechanical failure was 91% at 5 and 10 years, and no aseptic mechanical failures occurred after 2 years.
Corona et al. (2021) [24] | 10 | Adult non-oncologic infected post-traumatic distal femur defects | 27 (median) | Not separately reported | Limb salvage was achieved in all cases, with no recurrence of infection during follow-up.
Monument et al. (2015) [25] | 22 | Femoral oncologic cohort, including distal femur 19 and proximal femur 3 | Minimum 60 | 4.5% (n = 1) | Five-year survivorship free from aseptic failure was 89%.
Kagan et al. (2017) [26] | 114 | Lower extremity reconstruction cases, including primary oncologic 40, revision arthroplasty 69, and fracture 5 | 41 (mean) | 5.3% (n = 6; aseptic mechanical failure) | Overall failure rate was 22%, largely due to infection and tumor; aseptic mechanical failure accounted for 5.3% of cases.

Feature | Compress® compliant pre-stress device | Traditional cemented stem
Primary failure mode | Early periprosthetic fracture/Lack of osseointegration | Late aseptic loosening/Osteolysis
Timing of failure | < 2 years (Early) | > 5–10 years (Late, progressive)
Fracture rate | 2.7–3.9% | Variable (associated with osteolysis)
Aseptic loosening rate | 5–11% (at 5 years) | 12–15% (at 10 years)
Bone stock preservation | High (Minimal resection for revision) | Low (Significant bone loss during removal)
Revision complexity | Low to Moderate | High
Weight-bearing protocol | Protected for 6–12 weeks | Immediate to early

Temporal pattern of failure

A consistent temporal pattern of events was observed across all studies (Table 1; Fig. 3). Unlike the traditional cemented stem, where the risk of failure increases with over time owing to wear debris and osteolysis [29, 30], periprosthetic fractures with the CPS device occur primarily within 2 years after surgery. In the series by Tyler et al. [11], the median time to fracture was 6 months, with a range of 2–20 months. All six periprosthetic fractures occurred within 24 months of implantation, and the osseointegration interface remained stable in all cases (Fig. 3). Goldman et al. [23] explicitly stated that spindle failures only occurred in the first 2 years, with no mechanical failures thereafter. This temporal distribution suggests that once osseointegration and cortical hypertrophy were achieved, the construct becomes mechanically robust. Healey et al. [12] supported this observation and stated that most mechanical complications occurred during the first 18 months, after which the implant demonstrated excellent survivorship. As shown in Fig. 3, aseptic mechanical failures were commonly clustered during the early postoperative period. The 5-year and 10-year survival rates remained constant at 91%, suggesting that no further late mechanical failures occurred after the critical osseointegration period.

Fig. 3: Temporal Pattern of Complications Associated with the Compress® Device. Temporal distribution of complications between the Compress® device and traditional cemented stem. Top Panel (Red): Periprosthetic fractures (n = 6/221, 2.7%) occurred exclusively within the first 24 months post-implantation (median: 6 months), with all cases maintaining stable osseointegration interfaces despite fracture. Middle Panel (Orange/Green): Aseptic mechanical failures clustered within the first 24 months, after which no additional failures occurred, resulting in 91% survivorship at 5 and 10 years. The green zone represents a “no failures” period after successful osseointegration. Bottom Panel (Purple): Historical control data from cemented stems showing a continuous, progressive failure pattern throughout the follow-up period, contrasting sharply with the early-onset, time-limited failure pattern of the Compress® device. This unique temporal profile suggests that the critical period for complications associated with the Compress® device is during initial osseointegration (0–24 months), after which the construct demonstrates excellent durability. Key: Red dots = periprosthetic fracture events; orange dots = aseptic mechanical failure events; purple dots = cemented stem failure events (historical data)

Pediatric outcomes

High activity levels and skeletal immaturity contribute to unique challenges in the pediatric population. Tanaka et al. [22] included 36 pediatric patients who received distal femoral CPS devices with expandable components, with a mean follow-up duration of 87.4 months. Although the overall mechanical complication rate was high (81% experienced some type of International Society of Limb Salvage failure) because of the complexity of the expandable components, spindle survivorship was 86.3% at 5 years and 66.2% at 10 years. Periprosthetic fractures occurred in 16.7% (6/36) of pediatric patients, with a mean time to fracture of 5.7 years [22]. These findings suggest that greater activity levels and prolonged skeletal remodeling in pediatric patients may contribute to a different fracture risk profile than that observed in adults.

Interface stability during fracture events

Another important conclusion drawn from the reviewed studies is that the stability of the bone–implant interface during fracture events is key. Tyler et al. [11] noted that the osseointegrated interface remained radiographically stable in all six periprosthetic fractures. The most common fracture pattern occurred above the anchor plug (five of six cases), with only one fracture at the anti-rotation pin insertion site. This stability offers less aggressive revision protocols than those required for failed traditional cemented stems, which often require extended osteotomies or cortical windowing to remove cement [31, 32]. Regarding infected reconstructions, Corona et al. [24] noted that despite difficult cases of bone loss and infection, preservation of the compression interface can be accomplished during revision. Preserving an osseointegrated interface preserves the bone stock and makes revision surgery more accessible. Generally, as illustrated in Fig. 1, the revision plan consists of stem extension with plating or a two-stage strategy in cases of infection, with the goal of restoring function and maintaining the osseointegration.

Survivorship data across studies

Table 3 summarizes the survivorship data across major studies. Overall survivorship from aseptic mechanical failure ranged from 85 to 95% at 5 years across studies, which compares favorably with historical data for the traditional cemented stem [33, 34]. Monument et al. [25] reported 89% survivorship of aseptic failure at 5 years, and Zimel et al. [35] demonstrated 89% survivorship at 5 and 10 years, suggesting that the failure rate plateaued after the initial 2-year risk period.

Study | Follow-up period | Overall survival | Aseptic mechanical failure | Spindle survival | Notes
Tyler et al. [11] | 4.2 years (mean) | Not reported | 2.7% fracture rate | 97.3% | Early series, learning curve
Healey et al. [12] | 5 years | 85% | 15% | 85% | At 10 years: 80% survival
Monument et al. [27] | 5 years | 89% | 11% | 89% | Femoral locations only
Goldman et al. [23] | 5–10 years | 91% | 9% | 91% | Distal femur specific
Zimel et al. [35] | 10 years | 89% | 11% | 89% | Revision series
Tanaka et al. [22] | 5–10 years | 86.3% | 13.7%* | 86.3% | Spindle-specific survival

Risk factor analysis

Available evidence regarding risk factors was limited and heterogeneous; however, several factors were repeatedly implicated across studies (Table 4). Traditional demographic variables such as age, sex, and body mass index, were not consistently associated with fracture risk. In contrast, device- and treatment-related factors appeared to be more relevant, including cortical thickness < 2.5 mm, early weight bearing before osseointegration, limited surgeon experience, active chemotherapy, planned radiation therapy, high activity levels, and distal femoral reconstruction.

Risk factor | Risk level | Evidence quality | References | Notes
Cortical thickness < 2.5 mm | High | Strong | [12] | Manufacturer contraindication
Early weight bearing | Moderate | Moderate | [1] | Within the first 6–12 weeks
Surgeon experience < 5 cases | Moderate | Limited | [28] | Learning curve effect
Age > 70 years | Low | Conflicting | [27, 28] | Not consistently demonstrated
Chemotherapy (active) | Low | Weak | [40] | May delay but not prevent osseointegration
Radiation therapy (planned) | Moderate | Limited | [28] | Relative contraindication
High activity level | Low-Moderate | Limited | [2] | Mainly in pediatric populations
Anatomic location | Variable | Moderate | [1, 4] | Distal femur may have higher rates