Patellar dislocation following distal femoral replacement after extra-articular knee resection for bone sarcoma: A case report

Table 1 Complications of distal femoral replacement

Ref.	Total cases	Age (yr)1	Average follow-up (mo)1	Extra-articular cases	Implant type	Overall survival	Disease-free survival	Local recurrence	Limb salvage	Implant survival (without re-operation)	Function score1	Total complication	Infection	Aseptic loosening	Implant failure	Peri- prosthetic fracture	Other complicationsl	Revision
Kendall et al[4], 2000	12 (3 died who were excluded from their case matched study)	32.7 (20-64)	18 (6-56)	9 cases	Rotating hinge: 8 cases; fixed hinge: One case	9/12 (75%)	5/12 (42%; 1 case had a local and 3 had systemic recurrences)	1 case	Amputation/disarticulation: 2 cases	Revision of components: 0 case; amputation/disarticulation: 2 cases	Musculoskeletal Tumour Society (%): 56.14; Knee Society (points), 130.14	12 cases (including amputation and recurrence)	Superficial, 2 cases; deep, 2 cases	NA	NA	NA	Dislocation of component: 1 case	Rebushing: 1
Sim et al[5], 2007	50	40.5 (13-79)	24.5 (2-124)	NA (all cases: Wide en bloc resection)	Rotating hinge	Median: 9.5 mo (metastatic bone tumor) and 23.5 mo (primary malignancy). Eight documented deaths	77% (39 patients were initially metastasis-free, 9 subsequently developed metastasis) metastatic disease	0 case	Amputation: 3 cases	5 patients required endoprosthetic revision, 3 patients underwent subsequent amputation	NA	17 (34%)	Superficial, 4 cases; deep, 6 cases	1 case	Mechanical wear: 2 cases	2 cases	Nerve palsies, 5 cases	5 patients require endoprosthetic revision (10%)
Kinkel et al[3], 2010	77	38 (11–78)	46 (3–128)	EAR, 31 cases	Rotating hinge	NA	97% (primary malignant tumor)	4 cases	92% (both 5 and 10 yr)	57% after 5 yr	Enneking score, 73%	64 complications occurred (46 patients)	11 cases	13 cases (17%)	Locking mechanism failure, 15 cases	3 cases	Reduced ROM, 5 cases; rupture of the patellar tendon, 1 case	70 surgical revisions in 45 patients (58%)
				Intraarticular resection, 46 cases								-
Zwolak et al[6], 2011	11	39.8 (15-79)	37.5 (14-80)	11	Rotating hinge 1 case; not mentioned in others	9/11 (81.8%)	7/11 (6 patients developed metastasis)	1 case	100 %	100%	NA	NA	NA	NA	No complications were associated with the extensor mechanism of the patellar, specifically no patellar fracture was detected	NA	NA	0 case
Capanna et al[7], 2011	14	34.9 (17-68)	54 (12-144)	13	Rotating hinge in some cases	10/14 (71.4%)	8/14 (57.4%)	3 cases	100%	1 patient with an intercalary arthrodesing prosthesis (Megasystem C, Waldemar Link)	MSTS-ISOLS score, 83% (67- 90)	10 patients	Deep infection, 2 cases	0 case	1 case	0 case	Rupture of the patellar tendon, 2 cases	Infection, 2 cases; failure of the grafted patellar tendon, 2 cases
Hardes et al[8], 2013	59	33 (11-74)	56.4 (1-204)	55 (93%) underwent splitting of the patellar in the coronal plane; 4 (7%) underwent patellectomy	Rotating hinge	53/59 (89.3%)	49/59 (83%)	2 cases (3%)	76% at 151 mo	48% at 2 yr and 31% at 5 yr postoperatively	The mean MSTS functional score: 22 (10-29); the mean OKS score: 32 (10-48)	NA	22 patients (37%)	10 cases (17%)	Failure of the joint mechanism (wear or breakage), 12 patients (20%)	6 patients (10%)	Delayed healing, 18 patients (31%)	A total of 110 revision procedures were carried out
Ieguchi et al[9], 2014	14	EAR, 44.4 (23-65)	EAR, 82.8 (24-176)	EAR, 6 patients	Rotating hinge, 5 cases; semi-rotating hinge, 1 case	5/6 (83.3%)	3/6 (50.0%)	0	5/6 (83.3%, 1 case of amputation)	5-yr survival rate of the prostheses without re-operation was 33.3%	In the extra-articular group, the mean total MSTS functional score, 21 (18-26)	NA	2 cases	0 case	Avulsion fractures of the patellar ligament, 2 cases (no data regarding how many cases occurred in the EAR group	Detachment of the patellar component, 1 case (no data regarding how many cases occurred in the EAR group	NA	2 cases (1 required amputation)
Shahid et al[10] , 2017	76	32 (9-74) EAR: 33 (11-73)	64 (12-195)	EAR: 42 cases (55%)	NA	5-yr survival 60%	NA	12/42 (29%); 5-yr survival, 69%	Amputation, 0 case	EAR: 5- and 10-yr reconstruction survival, 65% and 59%, respectively	MSTS 26 (24-30)	NA	NA	NA	NA	NA	NA	NA

¹Data are presented as median (range).

CI: Confidence interval; EAR: Extra-articular resection; MSTS: Musculoskeletal Tumor Society; ISOLS: International Symposium on Limb Salvage; NA: Not available; OKS: The Oxford knee score; PE: Polyethylene; ROM: Range of motion.