Unwin et al. in 1996, reviewed 1,001 Stanmore cemented custom made prostheses with fixed hinge mechanisms, inserted before 1992 as a primary replacement for bone tumor [9]. The probability of avoiding aseptic loosening for 10 years was reported as 93.8 % for the proximal femur, 67.4 % for the distal femur and 58 % for proximal tibia replacements. The amputation rate due to complications for the entire group was 8.6 %. Myers et al. in 2007, reported on 335 patients who underwent distal femoral replacement [24]. A total of 192 patients remained alive with a mean follow-up of 12 years. All prostheses were custom made. One hundred and sixty two patients had a fixed-hinge design and 173 a rotating-hinge of which 143 had a hydroxyapatite (HA) collar. Only 15 prostheses were uncemented. Patellar resurfacing was not routinely performed. Early failure was usually due to infection or breakage of the prosthesis whereas late failure was more likely to be due to aseptic loosening. If aseptic loosening was taken as the endpoint, the rotating-hinge design with an HA collar was least likely to fail. The risk of revision for aseptic loosening of a fixed-hinge was 35 % at 10 years compared with 24 % for a rotating-hinge without an HA collar and 0 % for a rotating-hinge with an HA collar. Rebushing of the primary endoprosthesis was needed in 55 prostheses (45 fixed-hinge, 10 rotating-hinge). The overall infection rate was 9.6 %. Amputation was performed in 6 % for local recurrence and in 4.5 % of patients due to infection. Schwartz et al. in 2009, compared 85 modular distal femoral implants to 101 custom-casted designs [12]. All prostheses were cemented with a rotating hinge mechanism. The modular components had a greater 15-year survivorship than the custom-designed implants: 93.7 % versus 51.7 %, respectively. 9.7 % of the patients ultimately required amputation. The authors conclude that long-term survivors should expect at least one or more revision procedures in their lifetime. Bergin et al. in 2012, published the results of 104 distal femoral reconstructions [25]. They focused their analysis on the impact of the bone/stem ratio on aseptic loosening rate. All patients received a cemented modular prosthesis. Survival for 104 stems from aseptic loosening was 94.6 % at 10 and 15 years and 86.5 % at 20 years. The bone/stem ratio independently predicted aseptic failure. Patients with stable implants had larger stem sizes and lower bone/stem ratios than those with loose implants (14.5 mm versus 10.7 mm and 2.02 versus 2.81, respectively). The largest cause of failure in this study was infection (11.7 %) while 5.8 % of the implants were revised because of stem fracture.

Batta et al. has reported a high rate of aseptic loosening for custom-made uncemented, distal femoral endoprosthetic replacements [26]. Nine out of 69 implants (13 %) had to be revised due to aseptic loosening. All aseptically loose implants were diagnosed within the first 5 years. Capanna et al. in 1993, reports the results of 95 modular uncemented KMFTR tumor prostheses for distal femoral resections [27]. The femoral stem had two lateral flanges at right angles to each other, each with three holes to allow the passage of a total of six screws through the stem and cortex. Clinical results were excellent or good in 75 %. Local recurrence of the tumors developed in five patients. The polyethylene bushes failed in 42 % of cases at an average of 64 months postoperatively, causing varus-valgus instability or locking, usually painless. The infection rate was 5 % for primary cases and was correlated to the extent of quadriceps excision. Bone remodeling around the femoral stem was evaluated on X-rays using the Rizzoli system. According to this system, in grade A there is no change, Grade B there is cortical sclerosis, Grade C there is cortical cancellation, Grade D there is distal sclerosis and proximal atrophy and in Grade E there is proximal osteolysis. In their series Grade D remodeling occurred in 47 % of the prostheses fixed with six screws and in only 11 % with three screws. Stem breakage occurred in 6 % and was associated with the use of narrow stems and extensive quadriceps excision. Most of the fractures occurred though the proximal screw hole. Lan et al. used dual-energy X-ray absorptiometry (DEXA) to evaluate the extent of periprosthetic bone remodelling around the KMFTR prosthesis for distal femoral reconstruction [28]. Bone loss around the KMFTR prosthesis was maximal at the distal end of the femur and progressively decreased towards the proximal end of the stem. Ten patients with implants fixed by screws were found to have a mean loss of bone mineral density (BMD) of 42 % in the most distal part of the femur, while the 13 without screw fixation had a mean loss of 11 %. Mittermayer et al. in 2002, reported on 251 uncemented reconstructions with the KMFTR system or the Howmedica Modular Reconstruction System (HMRS) [29]. Aseptic loosening rate at 10 years was 4 % for proximal femur, 24 % for distal femur replacements and 15 % for proximal tibia. The first radiological signs of aseptic loosening were always seen at the most proximal or distal part of the anchorage stem at a mean of 12 months after the first implantation. Griffin et al. in 2005, examined the risk factors associated with prosthetic failure for the KMFTR uncemented tumor prosthesis of 74 distal femoral [30]. For the distal femoral prosthesis the aseptic loosening rate was very low (2.7 %), the infection rate was 6.8 %, tumor local recurrence was 6.8 %, and the stem fracture rate 5.4 %. All stem fractures occurred through components with six holes for transverse screw fixation produced before 1994. No fractures occurred through newer components with only three holes.

For proximal tibia resections the common surgical approach is the anterior with proximal medial femoral extension, allowing for popliteal space exploration, identification of the popliteal neurovascular bundle, the trifurcation of the popliteal artery, arterial branches to gastrocnemius heads and common peroneal nerve (Fig. 20.2).

The reported results for proximal tibia replacement megaprostheses are frequently inferior to the distal femur. Two inherent characteristics of proximal tibia resection surgery are considered to be the principal causes for this outcome: defective attachment of the patellar tendon and the lack of available soft tissue. The attachment of the patellar tendon should be resected at least a few millimeters from the tibial tubercle in cases of malignancy, in order to achieve a clear oncological margin, thus resulting in a shortened tendon stump. In order to restore the continuity of the extensor mechanism, augmentation of the stump with synthetic or biological material is frequently necessary. This is the weak point for this step of reconstruction as reliable and effective long-term attachment of the tendon to the implanted prosthesis is not always successful. We frequently observe a gradual proximal migration of the patella on a lateral X-ray and a clinical lag of active, but full passive knee extension. Colangeli et al. in 2007, performed gait analysis of knee megaprostheses for proximal tibia tumors [31]. Functional performance during gait was abnormal in moss cases, consistent with weakness of the extensor apparatus and knee extension lag. Knee stability was supported by the intrinsic prosthesis biomechanics. The inadequacy of surrounding soft tissue for tension free coverage of the prosthesis (especially the metaphyseal part of the prosthesis) is the other major issue. Frequently, the proximal tibia has to be resected en block with the proximal fibula and an envelope of soft tissue for safe negative tumor margins. An important step in the evolution of limb sparing surgery for proximal tibia tumors was the concept of a local rotational flap of gastrocnemius head for prostheses coverage and anchorage of the patellar tendon [32, 33]. More recently the use of the Trevira attachment tube has been introduced to enhance joint capsule stability and tendon attachment [34]. The tube is directly attached to the tibial prosthesis with non-absorbable sutures. Fibroblasts migrate into the tube’s mesh, so that attachment of soft tissue takes place. In Hardes et al.’s series most of the patients were able to actively extend their knee [35].

Infection is a frequent complication of knee megaprosthesis reconstruction ranging from 3.6 % to 37.5 %, and it is a leading cause for amputation [12, 39–44] (Fig. 20.3). Body image is significantly worse for patients undergoing late amputation after failed limb salvage [45]. Hardes et al. in 2006, reported on 30 patients with an infection associated with a tumor endoprosthesis [46]. Limb salvage related to the complication infection was achieved in 63.3 %. The mean number of revision operations per patient was 2.6. No patient receiving chemotherapy with a poor soft tissue condition had limb salvage surgery. A poor soft tissue condition was a significant risk factor for failed limb salvage. Jeys and Grimer, in 2009, stated that the risk of infection is life-long although infection most frequently occurs within 12 months from the last surgical procedure [43]. The most common pathogenic organism is coagulase-negative Staphylococcus and the most effective treatment for deep infection is two-stage revision [43, 47]. Previous radiotherapy increases the infection rate [47]. Flint et al. in 2007, reported on 11 patients who underwent removal of the prosthesis for infection [48]. They concluded that two-stage revision of uncemented tumor endoprostheses with retention of a well-ingrown stem could be associated with successful eradication of infection. Racano et al. in 2013, conducted a systematic review of the literature for clinical studies that reported infection rates in adults with primary bony malignancies of the lower extremity treated with surgery and endoprosthetic reconstruction [49]. This review yielded 48 studies reporting on a total of 4,838 patients. The overall pooled weighted infection rate for lower-extremity LSS with endoprosthetic reconstruction was approximately 10 % with the most common causative organism reported to be Gram-positive bacteria in the majority of cases. The pooled weighted infection rate was 13 % after short-term postoperative antibiotics and 8 % after long-term postoperative antibiotics. Silver is well known for its anti-microbial properties. Silver coated megaprostheses are currently under investigation regarding their effect on incidence of deep infection and possible side effects [50, 51]. An in-vivo study in a rabbit model concludes that the silver coated Mutars megaprosthesis resulted in reduced infection rates without toxicological side effects [52]. Hardes et al. demonstrated a lower infection rate and less aggressive treatment of infection in patients treated with silver coated megaprostheses compared to titanium prostheses [53]. Shirai et al. in 2014, performed a clinical trial of iodine-coated megaprostheses to evaluate their safety and antibacterial effect [54]. Abnormalities of thyroid gland function were not detected. The authors conclude that the iodine-supported titanium megaprostheses were highly effective and showed promise in the prevention and treatment of infections in large bone defects.