Biomechanical Comparison of Adjustable-Loop Femoral Cortical Suspension Devices for Soft Tissue ACL Reconstruction

Background

Several new adjustable-loop devices (ALDs) for anterior cruciate ligament reconstruction (ACLR) have not been tested in vitro.

Purpose

To compare the biomechanical performances of 5 ALDs under a high cyclic load and forces representative of the return-to-play conditions seen in the recovering athlete.

Study Design

Controlled laboratory study.

Methods

A total of 10 devices for each of 5 chosen ALDs (UltraButton [Smith & Nephew], RigidLoop [DePuy Mitek], ProCinch [Stryker], TightRope [Arthrex], and ToggleLoc [Biomet]) were tested in a device-only model. The devices were secured to a servohydraulic test machine and preconditioned from 10 to 75 N at a rate of 0.5 Hz for 20 cycles. They were then subjected to high cyclic forces (100-500 N for 4000 cycles) and subsequently pulled to failure at 50 mm/min. The preconditioning displacement, permanent deformation, cumulative peak displacement, stiffness coefficient, and load to failure data were collected.

Results

The UltraButton displayed the greatest preconditioning displacement (0.22 ± 0.20 mm), followed by the RigidLoop (0.11 ± 0.03 mm), ProCinch (0.07 ± 0.04 mm), TightRope (0.07 ± 0.02 mm), and ToggleLoc (0.02 ± 0.03 mm). The TightRope displayed the greatest permanent deformation (3.19 ± 1.03 mm) followed by the UltraButton (2.14 ± 0.92 mm), ToggleLoc (2.02 ± 1.09 mm), RigidLoop (1.67 ± 0.1 mm), and ProCinch (1.38 ± 0.18 mm). The TightRope displayed the greatest cumulative peak displacement (3.69 ± 1.03 mm) followed by the UltraButton (2.46 ± 0.92 mm), ToggleLoc (2.37 ± 1.08 mm), RigidLoop (2.01 ± 0.1 mm), and ProCinch (1.75 ± 0.19 mm). The UltraButton displayed the largest stiffness coefficient (1347.22 ± 136.33 N/mm) followed by the RigidLoop (1325.4 ± 116.37 N/mm), ToggleLoc (1216.62 ± 131.32 N/mm), ProCinch (1155.56 ± 88.04), and TightRope (848.48 ± 31.94). The ToggleLoc displayed the largest load to failure (1874.42 ± 101.08 N) followed by the RigidLoop (1614.12 ± 129.11 N), UltraButton (1391.69 ± 142.04 N), ProCinch (1384.85 ± 58.62 N), and TightRope (991.8 ± 51.1 N.).

Conclusion

The 5 ALDs exhibited different biomechanical properties. None of them had peak cumulative displacements for which the confidence interval lay above 3 mm, thus no single device was determined to have a higher rate of clinical failure compared with the others.

Clinical Relevance

ALD choice may affect biomechanics after ACLR.

Pediatric On-Call Challenges for the General Orthopaedic Surgeon

Taking call as an orthopaedic surgeon is commonplace and expected at many institutions. Taking general orthopaedic call without specialized backup physicians can be challenging and daunting. Pediatric patients commonly present to emergency departments around the country with a host of pathologies, many of which are different from those of adults. It is imperative to recognize injuries and scenarios that require emergent or urgent intervention, those that can potentially become difficult, and how to triage nonurgent ones. Just as important is identifying one's ability to treat these patients (as a surgeon or an institution) and the capacity and mechanism to transfer these patients to specialized care centers. The general orthopaedic surgeon will be required to assess on-call challenges with pediatric patients.

Modified Langenskiöld procedure for chronic, recurrent, and congenital patellar dislocation

PURPOSE

Langenskiöld described a reconstructive soft-tissue procedure for irreducible lateral congenital patellar dislocations. Paley further detailed the technique in the surgical management of congenital femoral deficiency. The aim of this study was to evaluate the outcomes of patients with congenital, chronic and recurrent patellar dislocations treated with the modified Langenskiöld procedure.

METHODS

This is a retrospective case series. Between 2011 and 2018, 18 knees in 13 patients (mean age 15.8 years (sd 4.4; 12 to 29.9), nine female) with diagnoses of recurrent (six patients, eight knees), chronic (four patients, six knees) and congenital (three patients, four knees) patellar dislocations were treated with the modified Langenskiöld procedure.

RESULTS

There were no recurrent lateral dislocations in the congenital or recurrent groups. One of the patients in the congenital group had an overcorrection with some medial patellar maltracking but until this time has not required any further surgery. In the chronic group two of the six knees developed further dislocations; these were both on the same patient, who had no dislocations until one year after surgery. Mean Kujala score was 83.7 (sd 17; 47 to 100) for all groups. In spite of preoperative knee flexion contractures of up to 30° in three patients (six knees), all patients had full extension postoperatively. Eight patients reported being satisfied with their outcome, one was somewhat satisfied, two were very dissatisfied, and two did not respond.

CONCLUSION

The modified Langenskiöld reconstruction provides a powerful correction for challenging cases of congenital and recurrent patellar dislocations. Re-dislocation as well as overcorrection can occasionally occur.

LEVEL OF EVIDENCE

Level IV.

COVID-19 pandemic and the implications for orthopaedic and neurosurgery residents and fellows on spine rotations

Background

The COVID-19 global pandemic has caused unprecedented levels of strain on the United States healthcare and its workforce. Orthopaedic and neurosurgery residents and fellows, as part of this workforce have also experienced some of the uncertainty and stress caused by this pandemic. Concerns exist regarding the effects of the pandemic on spine surgery education due to the cancellation of all elective surgeries.

Current Context

We explore how this pandemic is affecting orthopaedic and neurosurgery residents and fellows and their spine surgery education and experience. We also examined measures taken by the residency and fellowship programs to protect their residents and fellows, and measures taken by regulatory agencies like the ACGME and the ABOS to give programs some flexibility during these difficult times.

Conclusion

Orthopaedic and neurosurgery residents and fellows are often on the front lines of patient care. Programs have to ensure adequate resources and training, supervision, and work hour requirements are met. Residents and fellows need to be ready to assist with management of COVID-19 patients if necessary. Residency programs and spine surgery fellowships need to use objective metrics to assess the impact of the pandemic on the spine surgery education of their residents and fellows in order to address any potential area of weakness caused by the decreased exposure to spine surgery.

Focal Periphyseal Edema: An Uncommon Cause of Adolescent Knee Pain: A Report of Three Cases

CASE

Focal periphyseal edema (FOPE) zones have only recently been described as a cause of joint pain in adolescence. The literature is limited to a few case reports and radiologic studies describing this symptomatic physeal pathology. This series describes 3 adolescent patients with magnetic resonance imaging (MRI) confirmed FOPE zones of the distal femur. Repeat MRI of 2 of the 3 patients showed improvement yet incomplete resolution of the bone edema, corresponding with persistent knee pain.

CONCLUSIONS

FOPE zones usually improve with conservative treatment, but may be a cause of persistent knee pain in adolescents.

Intra-articular nodular fasciitis of the knee in a pediatric patient

The differential diagnosis for an intra-articular lesion in the knee of a pediatric patient is broad. Diagnostic considerations include pigmented villonodular synovitis (PVNS)-the most common intra-articular tumor-and a variety of both benign and malignant tumors, including lipomas, hemangiopericytomas, nodular fasciitis, parosteal osteosarcomas, and fibromyxoid sarcomas. If there is concern over possible malignant lesions, a tumor surgeon should be consulted. Precise pathologic diagnosis is ideal for identifying these enigmatic lesions and for determining the appropriate treatment plan. This article presents the case of a 13-year-old boy who presented with 1-month duration of knee pain and no history of trauma to the extremity. Physical examination revealed pain along the medial and lateral joint lines, pain with range of motion, and limited range of motion of the affected knee. Magnetic resonance imaging revealed a 3×1×3-cm lesion in the posterolateral corner that was believed to be localized PVNS. Arthroscopically, there was no evidence of PVNS, but a posterolateral soft tissue mass was found and removed, which was pathologically diagnosed as a rare, benign, intra-articular nodular fasciitis. When working with intra-articular masses, it is important to assess the likelihood of malignancy and to both consult a tumor surgeon and use the appropriate surgical tumor principles when malignancy is a concern. Additionally, the pathology team should be consulted prior to surgery and be on standby during arthroscopic evaluation of the knee to help with precise diagnosis of the intra-articular mass. Discussing the case with the pathologist with imaging studies present is helpful and often aids in the diagnosis of the lesion.

Hip septic arthritis and other pediatric musculoskeletal infections in the era of methicillin-resistant Staphylococcus aureus

Pediatric musculoskeletal infections can cause devastating complications (including death) in this era of methicillin-resistant Staphylococcus aureus and other virulent bacterial strains. The complexity and severity of these infections require timely diagnosis and treatment. A thorough emergency department evaluation, diagnostic workup, and early surgical intervention can influence outcomes. Septic arthritis of the hip is best treated with open drainage and antibiotic therapy to avoid osteonecrosis of the hip and joint damage. Because of genetic changes and inducible resistance, methicillin-resistant Staphylococcus aureus causes more complex infections than in the past. Deep, soft-tissue abscesses; pyomyositis; osteomyelitis; and septic arthritis often occur concurrently, causing destruction of musculoskeletal tissue. Severe and life-threatening complications, such as septic emboli, deep venous thrombosis, and multiorgan system failure may result from these infections.

Inverse acyl phosph(on)ates: substrates or inhibitors of beta-lactam-recognizing enzymes?

Acyl phosph(on)ates represent a new class of inhibitors of beta-lactam-recognizing enzymes. Previously described members of this class were aroyl phosph(on)ates. These compounds have been shown to acylate and/or phosphylate the active site serine residue, leading to either transient or essentially irreversible inhibition [Li, N., and Pratt, R. F. (1998) J. Am. Chem. Soc.120, 4264-4268]. The present paper describes the synthesis and evaluation as inhibitors of an inverse pair of acyl phosph(on)ates that incorporate the amido side chain that represents a major substrate specificity determinant of these enzymes. Thus, N-(phenylacetyl)glycyl phenyl phosphate and benzoyl N-(benzyloxycarbonyl)aminomethyl phosphonate were prepared. The former of these compounds was found to be a substrate of typical class A and C beta-lactamases and of the DD-peptidase of Streptomyces R61; it thus acylates the active site serine. In contrast, the latter compound was an irreversible inhibitor of the above enzymes, probably by phosphonylation of the active site serine. With each of these enzymes therefore, the amido side chain rather than the acyl group dictates the orientation of the bound phosph(on)ate and thus the mode of reaction.

Translocation (2;14) associated with complex rearrangements of the Ig heavy chain in non-Hodgkin lymphoma

Cytogenetic analysis of a patient with non-Hodgkin lymphoma revealed the following karyotype: 49,XXX,t(2;14)(q21;q32),+4,+8,del(13)(q14q21). Southern blot analysis with an Ig region probe showed non-productive rearrangements indicative of a translocation involving the Ig locus. However, molecular cloning of the abnormal rearrangements did not show novel sequences derived from chromosome 2 but showed that the BCL-6 gene was juxtaposed to the IgH enhancer. Three further clones with abnormal rearrangements involving the Ig locus, particularly Iggamma3, were isolated. This suggests that the mature lymphoid cells, in this patient, were capable of undergoing indiscriminate switch cleavage and religation.

Identification of amplified genes in a patient with acute myeloid leukemia and double minute chromosomes

A case of acute myeloid leukemia (M2) with double minute chromosomes and complex karyotypic abnormalities was analyzed cytogenetically and molecularly. Comparative genomic hybridization (CGH) showed that the 8q24 region that contains the MYC oncogene was not amplified. Instead, amplification of chromosomal regions 11q23-->qter and 9p11-->pter was identified. Southern blot analysis confirmed the CGH findings and showed that the ETS1, FLI1, SRPR, NFRKB, and KCNJ5 genes located at 11q23-->24 were amplified, whereas the MLL at 11q23 was not amplified. Additionally, the IFN beta 1 and CDKN2A genes at 9p were amplified, but to a lesser degree. This is the first example of a case of acute myeloid leukemia with double minute chromosomes that has not involved amplification of either the MYC or the MLL genes.

Characterization of the C-MYC amplicon in a case of acute myeloid leukemia with double minute chromosomes

We have characterized the double minute chromosomes in a case of acute myeloid leukemia (AML). Southern blot analysis showed that the C-MYC was amplified. Further analysis with probes located both 3' and 5' of MYC indicated that the amplicon was at least 700 kb in size, extending from the papilloma virus integration site situated 500 kb 5' of MYC to the PVT gene located 280 kb 3' of MYC. This appears to be the largest MYC-containing amplicon in human leukemia.

Methylation status of the 3rd exon of the c-MYC oncogene in B-cell malignancies

We examined the methylation status of the third exon of the MYC oncogene in 39 patients with B-cell malignancies. DNA was digested with MspI plus EcoRI or HpaII plus EcoRI and hybridised with a probe specific for the third exon of MYC. Thirty four patients showed complete methylation of the CCGG site. Four patients, one with chronic B-cell leukaemia and one with pro-lymphocytic leukaemia (PLL) and two with B-cell lymphoma showed partial hypomethylation of the CCGG site, while another patient with PLL showed complete hypomethylation of the CCGG site. These results suggest that hypomethylation of the MYC oncogene is infrequent in B-cell tumours but may be involved in the development of some cases of B-cell malignancies.

Aberrant rearrangements of the immunoglobulin heavy chain switch region in chronic B-cell leukemia

Analysis of the organisation of the Cmu-switch region of the immunoglobulin heavy chain locus in B-lymphocytes from 80 patients with chronic B-cell leukemia revealed 25 patients with abnormal rearrangements that could not be explained by the normal recombination events that take place in B-lymphocytes. Detailed analysis with probes spanning the Cmu -switch region and various restriction digests localised the rearrangements in two thirds of the patients to a 1300 bp region at the 5' end of the switch region while in the remaining patients the rearrangements occurred in the switch region. The consequences of these aberrant rearrangements remain to be determined, but their clustering to a defined region of the switch region suggests a "hot spot" that may be involved in the aetiology of the disease.

Predilection for frailty remedial strategies among black and white seniors

BACKGROUND

Frailty prevention and remedial programs based on exercise, hormone replacement, and vitamin supplementation are becoming available for use with older patients, but success of these programs depends largely on seniors' willingness to participate.

METHODS

We evaluated preferences for specific aspects of these programs using a sample of 359 older persons recruited from potential delivery sites. Main effects and subgroup analyses were done.

RESULTS

Subjects preferred stretching, chair-based, walking, and dynamic balance exercises over lifting weights, dancing, hormone and vitamin therapy; exercising alone in their own homes over exercising in groups; and vitamins over hormones. Preferences were affected to some extent by sex, race, recruitment site, and functional status. However, subjects' willingness even to consider exercise was rarely as high as the desired levels of participation set forth in Healthy People 2000.

CONCLUSIONS

Physicians and public health authorities need to educate older persons about effective methods to prevent or treat frailty.

Hypermethylation of the M27beta (DXS255) locus in chronic B-cell leukaemia

We have investigated the methylation status of the M27beta (DXS255) locus in 21 female patients with chronic B-cell leukaemia and in 20 normal controls. DNA was digested with Pst1 and then with the methylation sensitive enzyme HpaII and probed with the M27beta probe. Eight patients (38%) showed hypermethylation of the M27beta locus which was not seen in any of the normal controls. Hypermethylation of the M27beta locus has also been found in acute myeloid leukaemia, acute lymphocytic leukaemia and lymphoma, suggesting that hypermethylation of the M27beta locus is associated with the leukaemic process.

Elevated frequency of the C2 allele of the ETS-I oncogene in elderly subjects

We studied the frequency of an Sst I polymorphism of the ETS-I oncogene in 122 elderly subjects (mean age 78.14 years) and 115 teenagers (mean age 16.9 years). No difference in the frequency of the three genotypes (C1C1, C1C2, C2C2) was found between the two groups. However, the C2 allele occurred more frequently in the elderly subjects (chi 2 = 5.49, P < 0.02). These data suggest that the presence of the C2 allele may be associated with survival to old age.

Elevated frequency of a SstI polymorphism of the Ets-1 oncogene in non-Hodgkin's lymphoma patients

We studied the frequency of a SstI polymorphism of the Ets-1 oncogene in 100 patients with non-Hodgkin's lymphoma, 44 patients with Hodgkin's disease, 49 patients with chronic myeloid leukemia, and 100 controls. There was no difference in the genotype frequency between the controls and patients with either Hodgkin's disease or chronic myeloid leukemia. In contrast, there was a highly significant difference in the distribution of the three genotypes between the patients with non-Hodgkin's lymphoma and the controls (X2 = 10.76, 2df, p = 0.004) with the C2 allele being more frequent in the lymphoma patients. Molecular cloning indicated that the polymorphic SstI site lay 304 bp from exon 7. This is the second association of the SstI polymorphism of the Ets-1 oncogene with a lymphoid disorder and suggests that the presence of the C2 allele is associated with a predisposition to develop a lymphoid malignancy.

Identification of three RFLPs at the HCK locus on chromosome 20

New HindIII, RsaI and TaqI restriction fragment length polymorphisms (RFLPs) within the haemopoietic cell kinase gene in chromosome band 20q11.2 are described. These RFLPs provide a useful marker for linkage analysis in proximal 20q.

Increased frequency of the S allele of the L-myc oncogene in non-Hodgkin's lymphoma

We studied 100 patients with non-Hodgkin's lymphoma, 44 patients with Hodgkin's disease and 100 controls for the prevalence of the EcoRI restriction fragment polymorphism of the L-myc oncogene. No difference in the frequency of the three genotypes (LL, LS, SS) was found between the patient and control groups. However, the S allele was found to occur more frequently in the non-Hodgkin's lymphoma patients (chi 2 = 4.57, P = 0.032). These data confirm an earlier report and suggest that the presence of the S allele is associated with susceptibility to non-Hodgkin's lymphoma.

Cloning and sequencing of a t(14;19) breakpoint that involves the C mu switch region

The t(14;19) is a recurring translocation found in a small number of cases of chronic B-cell leukemia (CLL). We have cloned and sequenced the breakpoint in a patient with a t(14;19) and shown that the breakpoint on chromosome 14 occurred in the C mu switch region, and that the breakpoint on chromosome 19 occurred in the 5' untranslated region of the BCL3 gene. This is in contrast to all the other reported cases with a t(14;19) in which the breakpoints on chromosome 14 occurred in the C alpha 1 or C alpha 2 switch region, and the breakpoints on chromosome 19 occurred upstream of the BCL3 gene. Our results further emphasize the importance of the switch region in the t(14;19) translocation.

Oligoclonal B-cell leukemia characterized by spontaneous cell division and telomere association

Cytogenetic analysis of unstimulated cultures from a female patient with chronic B-cell leukemia (CLL) revealed three cytogenetically distinct clones, suggesting that the patient's leukemia was oligoclonal. Immunoglobulin heavy chain gene rearrangement studies revealed 1 germline and 4 rearranged bands, indicative of an oligoclonal leukemic population. Further evidence of oligoclonality was provided by X-linked RFLP studies. This is the first report of oligoclonality in CLL demonstrated by cytogenetic, immunoglobulin gene rearrangement, and X-chromosome inactivation studies. In addition to oligoclonality, the patient's leukemic cells exhibited telomere association, a Robertsonian translocation, and clonal evolution, suggesting an underlying genomic instability.

Lack of 5' BCL2 rearrangements in B-cell leukemia

We found no rearrangements in the 5' region of the BCL2 gene in DNA samples from 60 patients with chronic B-cell leukemia (CLL). This compares with the presence of these rearrangements in up to 10% of patients in other reports, and suggests that the incidence of 5' BCL2 rearrangements in CLL is considerably less than 10%.

Elevated frequency of an ETS-1 restriction fragment polymorphism in chronic B-cell leukaemia

We studied the frequency of an SstI polymorphism in 70 patients with chronic B-cell leukaemia (CLL) and 100 normal controls. There was a highly significant difference in the distribution of the three genotypes between the CLL patients and the normal controls (chi 2 = 13.46, 2 df, P < 0.001). The C2 allele was found more frequently in CLL patients and may be a marker for a predisposition to develop CLL.

XbaI RFLP of ETS-1 oncogene in chronic B-cell leukaemia

The influence of a polymorphic variant of the ETS-1 oncogene on the predisposition to develop chronic B-cell leukemia (CLL) was investigated. A total of 59 patients with CLL and 59 controls were examined for the frequency of an XbaI restriction fragment length polymorphism RFLP of the ETS-1 oncogene which has been reported to occur more frequently in patients with hematological malignancies than in normal controls. We found no significant difference in the allele frequency between the CLL patients and the normal controls. These data suggest that the presence of the XbaI RFLP is not associated with CLL.

Selection of test locations for regional trials of barley

Three sets of regional six-row barley (Hordeum vulgare L.) trial data, representing cultivar x location x year, were grouped for locations based on the similarity of genotype x environment (GE) interaction. Locations were selected from each group (cluster) so that the structure of the GE interaction generated by the subsets of the locations would be approximately similar to that of the whole set (all locations). The purpose of this paper is to determine the number of locations where the GE interaction structure generated by these selected locations would be fairly consistent over years. Two statistics were used to measure the success of the selected locations: (1) the ratio of GE mean square (MS) associated with the selected location set relative to that associated with the best set (which gives the highest GE interaction MS) and (2) the rank correlation between the cultivar means averaged over the selected locations and those based on the entire data set. The results show that, for eastern Canada, 10-13 locations based on the cluster method can achieve a fairly consistent GE interaction structure over years.

A process for implementation of the strategic plan: from strategic planning toward strategic management

Although the principles and process for developing a strategic plan are well established, little information exists on how organizations can implement these plans. The authors developed a framework and methodology for The Ontario Cancer Institute/Princess Margaret Hospital that connects the implementation of the strategic plan with resource allocation and the budget; thus, the budget is a quantified expression of the strategic plan. To accomplish this, a specific cycle of events leading to the development of a corporate calendar was undertaken, which results in the establishment of the annual budget.

Planning for shared services: lessons from experiences of the Princess Margaret Hospital

The plan to rebuild The Princess Margaret Hospital (PMH) on University Avenue in Toronto has provided several opportunities for institutions in the area to share programs and services. The PMH planning process has raised questions about the factors that influence the development of shared services plans, and the organizational and management challenges posed by such plans. This experience suggests 13 principles to develop effective shared services.

Complex karyotypic evolution in B-cell chronic lymphocytic leukemia

Cytogenetic analysis at diagnosis in a female patient with chronic B-cell leukemia showed a single abnormal clone with a 4p+ abnormality, 46,XX, -4, +der(4)t(4;?)(p16;?). Six additional clones evolved from this clone during the following 4 1/2 years and showed 3p+, 4p-, and 11q- chromosomes in addition to the 4p+ abnormality. Immunoglobulin heavy chain gene rearrangement studies showed two rearranged bands and a faint germline band. Following splenectomy, a strong germline and faint rearranged bands were seen, suggesting that the majority of cells were normal, whereas cytogenetic studies showed that the karyotypically abnormal cells were still present. The combination of cytogenetic and Ig gene rearrangement studies provides detailed information regarding the number of circulating normal and leukemic cells.

Diabetic neuroarthropathy in the foot: patient characteristics and patterns of radiographic change

The diagnosis of diabetic neuroarthropathy of the foot can be difficult. A series of 96 patients (116 extremities) who had diabetes and peripheral neuropathy with bone and joint changes was reviewed. Typically, the patients were middle-aged or older, were taking insulin, and had had diabetes for more than 10 years. Retinopathy, nephropathy, and peripheral vascular disease were often present. There were abnormalities of vibratory sensation (94%) and of the gastrosoleus reflex (88%). The finding of specific radiographic abnormalities assisted but did not reliably differentiate neuropathy from infection. Three patterns of radiographic changes were noted: (1) at the metatarsophalangeal and interphalangeal joints, usually with underlying ulceration; (2) at the tarsometatarsal joints; and (3) in the anterior pillar-medial column of the foot, with talus, talonavicular, navicular, or naviculocuneiform destruction. Ulceration and infection in patients with patterns (2) and (3) were rare. When correlated, the demographic features, mode of presentation, physical signs, specific radiographic abnormalities, and patterns of change were distinctive and allowed the diagnosis of this complication of diabetes to be readily made.

Hydroxyproline excretion in the detection of occult bone metastases from breast cancer

When surgery fails to cure breast cancer it is due to disseminated micrometastases present at the time of operation. The measurement of urinary hydroxyproline (OHP) is a possible screening test for such metastases in bone. This study compared both a single and serial urinary OHP estimation with the axillary node status, the bone scan status and the subsequent clinical course. A single measurement did not correlate with the axillary node or bone scan status, neither was there a relationship with the subsequent clinical course. Serial OHP estimations, every 3 months for a year, increased the accuracy of the test such that node-positive patients had higher excretions than node-negative patients (p less than 0.05). Patients who subsequently died with bone metastases tended to have a higher excretion than those who remained disease free, although this did not reach statistical significance. No relationship existed between serial OHP estimations and bone scan status. We consider the measurement of urinary OHP to be insufficiently sensitive to detect bone micrometastases and it is only raised when a substantial amount of bone is involved.